





Internet Engineering Task Force (IETF)                      T. Burbridge
Request for Comments: 8193                                    P. Eardley
Category: Standards Track                                             BT
ISSN: 2070-1721                                               M. Bagnulo
                                        Universidad Carlos III de Madrid
                                                        J. Schoenwaelder
                                                Jacobs University Bremen
                                                         August 21, 2017


    Information Model for Large-Scale Measurement Platforms (LMAPs)

Abstract

   This Information Model applies to the Measurement Agent within an
   LMAP framework.  As such, it outlines the information that is
   configured or preconfigured on the Measurement Agent or exists in
   communications with a Controller or Collector within an LMAP
   framework.  The purpose of such an Information Model is to provide a
   protocol- and device-independent view of the Measurement Agent that
   can be implemented via one or more Control and Report Protocols.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8193.

Copyright Notice

   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
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   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction
   2.  Requirements Language
   3.  Notation
   4.  LMAP Information Model
     4.1.  Preconfiguration Information
       4.1.1.  Definition of ma-preconfig-obj
     4.2.  Configuration Information
       4.2.1.  Definition of ma-config-obj
     4.3.  Instruction Information
       4.3.1.  Definition of ma-instruction-obj
       4.3.2.  Definition of ma-suppression-obj
     4.4.  Logging Information
       4.4.1.  Definition of ma-log-obj
     4.5.  Capability and Status Information
       4.5.1.  Definition of ma-capability-obj
       4.5.2.  Definition of ma-capability-task-obj
       4.5.3.  Definition of ma-status-obj
       4.5.4.  Definition of ma-status-schedule-obj
       4.5.5.  Definition of ma-status-action-obj
       4.5.6.  Definition of ma-status-suppression-obj
       4.5.7.  Definition of ma-status-interface-obj
     4.6.  Reporting Information
       4.6.1.  Definition of ma-report-obj
       4.6.2.  Definition of ma-report-result-obj
       4.6.3.  Definition of ma-report-conflict-obj
       4.6.4.  Definition of ma-report-table-obj
       4.6.5.  Definition of ma-report-row-obj
     4.7.  Common Objects: Schedules
       4.7.1.  Definition of ma-schedule-obj
       4.7.2.  Definition of ma-action-obj
     4.8.  Common Objects: Channels
       4.8.1.  Definition of ma-channel-obj
     4.9.  Common Objects: Task Configurations
       4.9.1.  Definition of ma-task-obj
       4.9.2.  Definition of ma-option-obj
     4.10. Common Objects: Registry Information
       4.10.1.  Definition of ma-registry-obj
     4.11. Common Objects: Event Information
       4.11.1.  Definition of ma-event-obj
       4.11.2.  Definition of ma-periodic-obj
       4.11.3.  Definition of ma-calendar-obj
       4.11.4.  Definition of ma-one-off-obj
       4.11.5.  Definition of ma-immediate-obj
       4.11.6.  Definition of ma-startup-obj
       4.11.7.  Definition of ma-controller-lost-obj
       4.11.8.  Definition of ma-controller-connected-obj
   5.  Example Execution
   6.  IANA Considerations
   7.  Security Considerations
   8.  References
     8.1.  Normative References
     8.2.  Informative References
   Acknowledgements
   Authors' Addresses

1.  Introduction

   A large-scale measurement platform is a collection of components that
   work in a coordinated fashion to perform measurements from a large
   number of vantage points.  A typical use case is the execution of
   broadband measurements [RFC7536].  The main components of a large-
   scale measurement platform are the Measurement Agents (MAs), the
   Controller(s), and the Collector(s).

   The MAs are the elements actually performing the measurements.  The
   MAs are controlled by exactly one Controller at a time, and the
   Collectors gather the results generated by the MAs.  In a nutshell,
   the normal operation of a large-scale measurement platform starts
   with the Controller instructing a set of one or more MAs to perform a
   set of one or more Measurement Tasks at a certain point in time.  The
   MAs execute the instructions from a Controller, and once they have
   done so, they report the results of the measurements to one or more
   Collectors.  The overall framework for a large-scale measurement
   platform as used in this document is described in detail in
   [RFC7594].

   A large-scale measurement platform involves basically three types of
   protocols, namely, a Control Protocol (or Protocols) between a
   Controller and the MAs, a Report Protocol (or Protocols) between the
   MAs and the Collector(s), and several measurement protocols between
   the MAs and Measurement Peers (MPs), used to actually perform the
   measurements.  In addition, some information is required to be
   configured on the MA prior to any communication with a Controller.

   This document defines the Information Model for both the Control and
   Report Protocols along with Preconfiguration Information that is
   required on the MA before communicating with the Controller, broadly
   named as the LMAP Information Model.  The measurement protocols are
   out of the scope of this document.

   As defined in [RFC3444], the LMAP Information Model defines the
   concepts involved in a large-scale measurement platform at a high
   level of abstraction, independent of any specific implementation or
   actual protocol used to exchange the information.  It is expected
   that the proposed Information Model can be used with different
   protocols in different measurement platform architectures and across
   different types of MA devices (e.g., home gateway, smartphone, PC, or
   router).  A YANG data model implementing the Information Model can be
   found in [RFC8194].

   The definition of an Information Model serves a number of purposes:

   1.  To guide the standardization of one or more Control and Report
       protocols and data models

   2.  To enable high-level interoperability between different Control
       and Report Protocols by facilitating translation between their
       respective data models such that a Controller could instruct sub-
       populations of MAs using different protocols

   3.  To form agreement of what information needs to be held by an MA
       and passed over the Control and Report interfaces and support the
       functionality described in the LMAP framework

   4.  To enable existing protocols and data models to be assessed for
       their suitability as part of a large-scale measurement system

2.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

3.  Notation

   This document uses a notation similar to a programming language to
   define the properties of the objects of the Information Model.  An
   optional property is enclosed by square brackets, [ ], and a list
   property is indicated by two numbers in angle brackets, <m..n>, where
   m indicates the minimal number of values, and n is the maximum.  The
   symbol * for n means no upper bound.

   The object definitions use several base types that are defined as
   follows:

   int         A type representing signed or unsigned integer numbers.
               This Information Model does not define a precision nor
               does it make a distinction between signed and unsigned
               number ranges.  This type is also used to represent
               enumerations.

   boolean     A type representing a boolean value.

   string      A type representing a human-readable string consisting of
               a (possibly restricted) subset of Unicode and ISO/IEC
               10646 [ISO.10646] characters.

   datetime    A type representing a date and time using the Gregorian
               calendar.  The datetime format MUST conform to RFC 3339
               [RFC3339].

   uuid        A type representing a Universally Unique IDentifier
               (UUID) as defined in RFC 4122 [RFC4122].  The UUID values
               are expected to be unique within an installation of a
               large-scale measurement system.

   uri         A type representing a Uniform Resource Identifier as
               defined in STD 66 [RFC3986].

   ip-address  A type representing an IP address.  This type supports
               both IPv4 and IPv6 addresses.

   counter     A non-negative integer that monotonically increases.
               Counters may have discontinuities, and they are not
               expected to persist across restarts.

   credentials An opaque type representing credentials needed by a
               cryptographic mechanism to secure communication.  Data
               models must expand this opaque type as needed and
               required by the security protocols utilized.

   data        An opaque type representing data obtained from
               measurements.

   Names of objects are generally assumed to be unique within an
   implementation.

4.  LMAP Information Model

   The information described herein relates to the information stored,
   received, or transmitted by a Measurement Agent as described within
   the LMAP framework [RFC7594].  As such, some subsets of this
   Information Model are applicable to the measurement Controller and
   Collector and to any device management system that preconfigures the
   Measurement Agent.  The information described in these models will be
   transmitted by protocols using interfaces between the Measurement
   Agent and such systems according to a data model.

   The Information Model is divided into six aspects.  Firstly, the
   grouping of information facilitates reader understanding.  Secondly,
   the particular groupings chosen are expected to map to different
   protocols or different transmissions within those protocols.

   1.  Preconfiguration Information.  Information preconfigured on the
       Measurement Agent prior to any communication with other
       components of the LMAP architecture (i.e., the Controller, the
       Collector, and Measurement Peers), specifically detailing how to
       communicate with a Controller and whether the device is enabled
       to participate as an MA.

   2.  Configuration Information.  Update of the Preconfiguration
       Information during the registration of the MA or subsequent
       communication with the Controller, along with the configuration
       of further parameters about the MA (rather than the Measurement
       Tasks it should perform) that were not mandatory for the initial
       communication between the MA and a Controller.

   3.  Instruction Information.  Information that is received by the MA
       from the Controller pertaining to the Measurement Tasks that
       should be executed.  This includes the Task execution Schedules
       (other than the Controller communication Schedule supplied as
       Configuration or Preconfiguration Information) and related
       information such as the Task Configuration, communication
       Channels to Collectors, and Event information.  It also includes
       Task Suppression information that is used to override normal Task
       execution.

   4.  Logging Information.  Information transmitted from the MA to the
       Controller detailing the results of any configuration operations
       along with error and Status Information from the operation of the
       MA.

   5.  Capability and Status Information.  Information on the general
       status and capabilities of the MA.  For example, the set of
       measurements that are supported on the device.

   6.  Reporting Information.  Information transmitted from the MA to
       one or more Collectors, including measurement results and the
       context in which they were conducted.

   In addition, the MA may hold further information not described
   herein, which may be optionally transferred to or from other systems
   including the Controller and Collector.  One example of information
   in this category is subscriber or line information that may be
   extracted by a Task and reported by the MA in the reporting
   communication to a Collector.

   It should also be noted that the MA may be in communication with
   other management systems that may be responsible for configuring and
   retrieving information from the MA device.  Such systems, where
   available, can perform an important role in transferring the
   Preconfiguration Information to the MA or enabling/disabling the
   measurement functionality of the MA.

   The granularity of data transmitted in each operation of the Control
   and Report Protocols is not dictated by the Information Model.  For
   example, the Instruction object may be delivered in a single
   operation.  Alternatively, Schedules and Task Configurations may be
   separated or even each Schedule/Task Configuration may be delivered
   individually.  Similarly, the Information Model does not dictate
   whether data is read, write, or read/write.  For example, some
   Control Protocols may have the ability to read back Configuration and
   Instruction Information that has been previously set on the MA.
   Lastly, while some protocols may simply overwrite information (for
   example, refreshing the entire Instruction Information), other
   protocols may have the ability to update or delete selected items of
   information.

   The information modeled by the six aspects of the Information Model
   is supported by a number of common information objects.  These
   objects are also described later in this document and are comprised
   of:

   a.  Schedules.  A set of Schedules tells the MA to execute Actions.
       An Action of a Schedule leads to the execution of a Task.
       Without a Schedule, no Task (including measurements or reporting
       or communicating with the Controller) is ever executed.
       Schedules are used within the Instruction to specify what Tasks
       should be performed, when, and how to direct their results.  A
       Schedule is also used within the Preconfiguration and
       Configuration Information in order to execute the Task or Tasks
       required to communicate with the Controller.  A specific Schedule
       can only be active once.  Attempts to start a Schedule while the
       same Schedule is still running will fail.

   b.  Channels.  A set of Channel objects are used to communicate with
       a number of endpoints (i.e., the Controller and Collectors).
       Each Channel object contains the information required for the
       communication with a single endpoint such as the target location
       and security details.

   c.  Task Configurations.  A set of Task Configurations is used to
       configure the Tasks that are run by the MA.  This includes the
       registry entries for the Task and any configuration parameters,
       represented as Task Options.  Task Configurations are referenced
       from a Schedule in order to specify what Tasks the MA should
       execute.

   d.  Events.  A set of Event objects that can be referenced from the
       Schedules.  Each Schedule always references exactly one Event
       object that determines when the Schedule is executed.  An Event
       object specifies either a singleton or a series of Events that
       indicate when Tasks should be executed.  A commonly used kind of
       Event object is the Timing object.  For Event objects specifying
       a series of Events, it is generally a good idea to configure an
       end time and to refresh the end time as needed to ensure that MAs
       that lose connectivity to their Controller do not continue
       executing Schedules forever.

   Figure 1 illustrates the structure in which these common information
   objects are referenced.  The references are achieved by each object
   (Task Configuration, Event) being given a short textual name that is
   used by other objects.  The objects shown in parenthesis are part of
   the internal object structure of a Schedule.  Channels are not shown
   in the diagram since they are only used as an option by selected Task
   Configurations but are similarly referenced using a short text name.

        Schedule
           |-- triggered by --> Event
           |
           |-- executes --> Action 1
           |                  |-- using --> Task Configuration
           |                  |
           |                  `-- feeding to --> Destination Schedule
           :
           :
           `-- executes --> Action N
                              |-- using --> Task Configuration
                              |
                              `-- feeding to --> Destination Schedule

      Figure 1: Relationship between Schedules, Events, Actions, Task
                 Configurations, and Destination Schedules

   The primary function of an MA is to execute Schedules.  A Schedule,
   which is triggered by an Event, executes a number of Actions.  An
   Action refers to a configured Task, and it may feed results to a
   Destination Schedule.  Both Actions and configured Tasks can provide
   parameters, represented as Action Options and Task Options.

   Tasks can implement a variety of different functions.  While in terms
   of the Information Model, all Tasks have the same structure, it can
   help conceptually to think of different Task categories:

   1.  Measurement Tasks measure some aspect of network performance or
       traffic.  They may also capture contextual information from the
       MA device or network interfaces such as the device type or
       interface speed.

   2.  Data Transfer Tasks support the communication with a Controller
       and Collectors:

       A.  Reporting Tasks report the results of Measurement Tasks to
           Collectors

       B.  One or more Control Tasks implement the Control Protocol and
           communicate with the Controller

   3.  Data Analysis Tasks can exist to analyze data from other
       Measurement Tasks locally on the MA.

   4.  Data Management Tasks may exist to cleanup, filter, or compress
       data on the MA such as Measurement Task results.

   Figure 1 indicates that Actions can produce data that is fed into
   Destination Schedules.  This can by used by Actions implementing
   Measurement Tasks to feed measurement results to a Schedule that
   triggers Actions implementing Reporting Tasks.  Data fed to a
   Destination Schedule is consumed by the first Action of the
   Destination Schedule if the Destination Schedule is using the
   sequential or pipelined execution mode, and it is consumed by all
   Actions of the Destination Schedule if the Destination Schedule is
   using parallel execution mode.

4.1.  Preconfiguration Information

   This information is the minimal information that needs to be
   preconfigured to the MA in order for it to successfully communicate
   with a Controller during the registration process.  Some of the
   Preconfiguration Information elements are repeated in the
   Configuration Information in order to allow an LMAP Controller to
   update these items.  The Preconfiguration Information also contains
   some elements that are not under the control of the LMAP framework
   (such as the device identifier and device security credentials).

   This Preconfiguration Information needs to include a URL of the
   initial Controller from where Configuration Information can be
   communicated along with the security information required for the
   communication, including the certificate of the Controller (or the
   certificate of the Certification Authority that was used to issue the
   certificate for the Controller).  All this is expressed as a Channel.
   While multiple Channels may be provided in the Preconfiguration
   Information, they must all be associated with a single Controller
   (e.g., over different interfaces or network protocols).

   Where the MA pulls information from the Controller, the
   Preconfiguration Information also needs to contain the timing of the
   communication with the Controller as well as the nature of the
   communication itself (such as the protocol and data to be
   transferred).  The timing is represented as an Event that invokes a
   Schedule that executes the Task(s) responsible for communication with
   the Controller.  It is this Task (or Tasks) that implements the
   Control Protocol between the MA and the Controller and utilizes the
   Channel information.  The Task(s) may take additional parameters, as
   defined by a Task Configuration.

   Even where information is pushed to the MA from the Controller
   (rather than pulled by the MA), a Schedule still needs to be
   supplied.  In this case, the Schedule will simply execute a
   Controller listener Task when the MA is started.  A Channel is still
   required for the MA to establish secure communication with the
   Controller.

   It can be seen that these Channels, Schedules, and Task
   Configurations for the initial communication between the MA and its
   Controller are no different in terms of the Information Model to any
   other Channel, Schedule, or Task Configuration that might execute a
   Measurement Task or report the measurement results (as described
   later).

   The MA may be preconfigured with an MA-ID or may use a Device ID in
   the first Controller contact before it is assigned an MA-ID.  The
   Device ID may be a Media Access Control (MAC) address or some other
   device identifier expressed as a URI.  If the MA-ID is not provided
   at this stage, then it must be provided by the Controller during
   Configuration.

4.1.1.  Definition of ma-preconfig-obj

     object {
         [uuid                ma-preconfig-agent-id;]
          ma-task-obj         ma-preconfig-control-tasks<1..*>;
          ma-channel-obj      ma-preconfig-control-channels<1..*>;
          ma-schedule-obj     ma-preconfig-control-schedules<1..*>;
         [uri                 ma-preconfig-device-id;]
          credentials         ma-preconfig-credentials;
     } ma-preconfig-obj;

   The ma-preconfig-obj describes information that needs to be available
   to the MA in order to bootstrap communication with a Controller.  The
   ma-preconfig-obj consists of the following elements:

   ma-preconfig-agent-id:          An optional UUID uniquely identifying
                                   the Measurement Agent.

   ma-preconfig-control-tasks:     An unordered set of Task objects.

   ma-preconfig-control-channels:  An unordered set of Channel objects.

   ma-preconfig-control-schedules: An unordered set of scheduling
                                   objects.

   ma-preconfig-device-id:         An optional identifier for the
                                   device.

   ma-preconfig-credentials:       The security credentials used by the
                                   Measurement Agent.

4.2.  Configuration Information

   During registration or at any later point at which the MA contacts
   the Controller (or vice versa), the choice of Controller, details for
   the timing of communication with the Controller, or parameters for
   the communication Task(s) can be changed (as captured by the
   Channels, Schedules, and Task Configurations objects).  For example,
   the preconfigured Controller (specified as a Channel or Channels) may
   be overridden with a specific Controller that is more appropriate to
   the MA device type, location, or characteristics of the network
   (e.g., access technology type or broadband product).  The initial
   communication Schedule may be overridden with one more relevant to
   routine communications between the MA and the Controller.

   While some Control Protocols may only use a single Schedule, other
   protocols may use several Schedules (and related Data Transfer Tasks)
   to update the Configuration Information, transfer the Instruction
   Information, transfer Capability and Status Information, and send
   other information to the Controller such as log or error
   notifications.  Multiple Channels may be used to communicate with the
   same Controller over multiple interfaces (e.g., to send Logging
   Information over a different network).

   In addition, the MA will be given further items of information that
   relate specifically to the MA rather than the measurements it is to
   conduct or how to report results.  The assignment of an identifier to
   the Measurement Agent is mandatory.  If the Measurement Agent
   Identifier was not optionally provided during the preconfiguration,
   then one must be provided by the Controller during Configuration.
   Optionally, a Group-ID may also be given that identifies a group of
   interest to which that MA belongs.  For example, the group could
   represent an ISP, broadband product, technology, market
   classification, geographic region, or a combination of multiple such
   characteristics.  Additional flags control whether the MA-ID or the
   Group-ID are included in Reports.  The reporting of a Group-ID
   without the MA-ID may allow the MA to remain anonymous, which may be
   particularly useful to prevent tracking of mobile MA devices.

   Optionally, an MA can also be configured to stop executing any
   Instruction Schedule if the Controller is unreachable.  This can be
   used as a fail-safe to stop Measurement and other Tasks from being
   conducted when there is doubt that the Instruction Information is
   still valid.  This is simply represented as a time window in seconds
   since the last communication with the Controller, after which an
   Event is generated that can trigger the suspension of Instruction
   Schedules.  The appropriate value of the time window will depend on
   the specified communication Schedule with the Controller and the
   duration for which the system is willing to tolerate continued
   operation with potentially stale Instruction Information.

   While Preconfiguration Information is persistent upon a device reset
   or power cycle, the persistency of the Configuration Information may
   be device dependent.  Some devices may revert back to their
   preconfiguration state upon reboot or factory reset, while other
   devices may store all Configuration and Instruction Information in
   persistent storage.  A Controller can check whether an MA has the
   latest Configuration and Instruction Information by examining the
   Capability and Status Information for the MA.

4.2.1.  Definition of ma-config-obj

     object {
         uuid                ma-config-agent-id;
         ma-task-obj         ma-config-control-tasks<1..*>;
         ma-channel-obj      ma-config-control-channels<1..*>;
         ma-schedule-obj     ma-config-control-schedules<1..*>;
         credentials         ma-config-credentials;
        [string              ma-config-group-id;]
        [string              ma-config-measurement-point;]
        [boolean             ma-config-report-agent-id;]
        [boolean             ma-config-report-group-id;]
        [boolean             ma-config-report-measurement-point;]
        [int                 ma-config-controller-timeout;]
     } ma-config-obj;

   The ma-config-obj consists of the following elements:

   ma-config-agent-id:                 A UUID uniquely identifying the
                                       Measurement Agent.

   ma-config-control-tasks:            An unordered set of Task objects.

   ma-config-control-channels:         An unordered set of Channel
                                       objects.

   ma-config-control-schedules:        An unordered set of scheduling
                                       objects.

   ma-config-credentials:              The security credentials used by
                                       the Measurement Agent.

   ma-config-group-id:                 An optional identifier of the
                                       group of Measurement Agents this
                                       Measurement Agent belongs to.

   ma-config-measurement-point:        An optional identifier for the
                                       measurement point indicating
                                       where the Measurement Agent is
                                       located on a path (see [RFC7398]
                                       for further details).

   ma-config-report-agent-id:          An optional flag indicating
                                       whether the Agent Identifier
                                       (ma-config-agent-id) is included
                                       in reports.  The default value is
                                       true.

   ma-config-report-group-id:          An optional flag indicating
                                       whether the Group-ID
                                       (ma-config-group-id) is included
                                       in reports.  The default value is
                                       false.

   ma-config-report-measurement-point: An optional flag indicating
                                       whether the measurement point
                                       (ma-config-measurement-point)
                                       should be included in reports.
                                       The default value is false.

   ma-config-controller-timeout:       A timer is started after each
                                       successful contact with a
                                       Controller.  When the timer
                                       reaches the controller-timeout
                                       (measured in seconds), an Event
                                       is raised indicating that
                                       connectivity to the Controller
                                       has been lost (see
                                       ma-controller-lost-obj).

4.3.  Instruction Information

   The Instruction Information Model has four sub-elements:

   1.  Instruction Task Configurations

   2.  Report Channels

   3.  Instruction Schedules

   4.  Suppression

   The Instruction supports the execution of all Tasks on the MA except
   those that deal with communication with the Controller (specified in
   Configuration or Preconfiguration Information).  The Tasks are
   configured in Instruction Task Configurations and included by
   reference in the Actions of Instruction Schedules that specify when
   to execute them.  The results can be communicated to other Schedules,
   or a Task may implement a Reporting Protocol and communicate results
   over Report Channels.  Suppression is used to temporarily stop the
   execution of new Tasks as specified by the Instruction Schedules (and
   optionally to stop ongoing Tasks).

   A Task Configuration is used to configure the mandatory and optional
   parameters of a Task.  It also serves to instruct the MA about the
   Task including the ability to resolve the Task to an executable and
   to specify the schema for the Task parameters.

   A Report Channel defines how to communicate with a single remote
   system specified by a URL.  A Report Channel is used to send results
   to a single Collector but is no different in terms of the Information
   Model to the Control Channel used to transfer information between the
   MA and the Controller.  Several Report Channels can be defined to
   enable results to be split or duplicated across different
   destinations.  A single Channel can be used by multiple (reporting)
   Task Configurations to transfer data to the same Collector.  A single
   Reporting Task Configuration can also be included in multiple
   Schedules.  For example, a single Collector may receive data at three
   different cycle rates, with one Schedule reporting hourly, another
   reporting daily, and a third specifying that results should be sent
   immediately for on-demand Measurement Tasks.  Alternatively, multiple
   Report Channels can be used to send Measurement Task results to
   different Collectors.  The details of the Channel element is
   described later as it is common to several objects.

   Instruction Schedules specify which Actions to execute according to a
   given triggering Event.  An Action extends a configured Task with
   additional specific parameters.  An Event can trigger the execution
   of a single Action, or it can trigger a repeated series of Actions.
   The Schedule also specifies how to link output data from Tasks to
   other Schedules.

   Measurement Suppression information is used to override the
   Instruction Schedule and temporarily stop measurements or other Tasks
   from running on the MA for a defined or indefinite period.  While
   conceptually measurements can be stopped by simply removing them from
   the Measurement Schedule, splitting out separate information on
   Measurement Suppression allows this information to be updated on the
   MA on a different timing cycle or protocol implementation to the
   Measurement Schedule.  It is also considered that it will be easier
   for a human operator to implement a temporary explicit Suppression
   rather than having to move to a reduced Schedule and then roll back
   at a later time.

   It should be noted that Control Schedules and Tasks cannot be
   suppressed as evidenced by the lack of Suppression information in the
   Configuration.  The Control Schedule must only reference Tasks listed
   as Control Tasks (i.e., within the Configuration Information).

   A single Suppression object is able to enable/disable a set of
   Instruction Tasks that are tagged for Suppression.  This enables
   fine-grained control on which Tasks are suppressed.  Suppression of
   both matching Actions and Measurement Schedules is supported.
   Support for disabling specific Actions allows malfunctioning or
   misconfigured Tasks or Actions that have an impact on a particular
   part of the network infrastructure (e.g., a particular Measurement
   Peer) to be targeted.  Support for disabling specific Schedules
   allows for particularly heavy cycles or sets of less essential
   Measurement Tasks to be suppressed quickly and effectively.  Note
   that Suppression has no effect on either Controller Tasks or
   Controller Schedules.

   Suppression stops new Tasks from executing.  In addition, the
   Suppression information also supports an additional boolean that is
   used to select whether ongoing Tasks are also to be terminated.

   Unsuppression is achieved through either overwriting the Measurement
   Suppression information (e.g., changing 'enabled' to False) or
   through the use of an end time such that the Measurement Suppression
   will no longer be in effect beyond this time.

   The goal when defining these four different elements is to allow each
   part of the Information Model to change without affecting the other
   three elements.  For example, it is envisaged that the Report
   Channels and the set of Task Configurations will be relatively
   static.  The Instruction Schedule, on the other hand, is likely to be
   more dynamic, as the measurement panel and test frequency are changed
   for various business goals.  Another example is that measurements can
   be suppressed with a Suppression command without removing the
   existing Instruction Schedules that would continue to apply after the
   Suppression expires or is removed.  In terms of the communication
   between the MA and its Controller, this can reduce the data overhead.
   It also encourages the reuse of the same standard Task Configurations
   and Reporting Channels to help ensure consistency and reduce errors.

4.3.1.  Definition of ma-instruction-obj

     object {
         ma-task-obj         ma-instruction-tasks<0..*>;
         ma-channel-obj      ma-instruction-channels<0..*>;
         ma-schedule-obj     ma-instruction-schedules<0..*>;
        [ma-suppression-obj  ma-instruction-suppressions<0..*>;]
     } ma-instruction-obj;

   An ma-instruction-obj consists of the following elements:

   ma-instruction-tasks:         A possibly empty unordered set of Task
                                 objects.

   ma-instruction-channels:      A possibly empty unordered set of
                                 Channel objects.

   ma-instruction-schedules:     A possibly empty unordered set of
                                 Schedule objects.

   ma-instruction-suppressions:  An optional possibly empty unordered
                                 set of Suppression objects.

4.3.2.  Definition of ma-suppression-obj

     object {
         string              ma-suppression-name;
        [ma-event-obj        ma-suppression-start;]
        [ma-event-obj        ma-suppression-end;]
        [string              ma-suppression-match<0..*>;]
        [boolean             ma-suppression-stop-running;]
     } ma-suppression-obj;

   The ma-suppression-obj controls the Suppression of Schedules or
   Actions and consists of the following elements:

   ma-suppression-name:          A name uniquely identifying a
                                 Suppression.

   ma-suppression-start:         The optional Event indicating when
                                 Suppression starts.  If not present,
                                 the Suppression starts immediately,
                                 i.e., as if the value would be
                                 'immediate'.

   ma-suppression-end:           The optional Event indicating when
                                 Suppression ends.  If not present, the
                                 Suppression does not have a defined
                                 end, i.e., the Suppression remains for
                                 an indefinite period of time.

   ma-suppression-match:         An optional and possibly empty
                                 unordered set of match patterns.  The
                                 Suppression will apply to all Schedules
                                 (and their Actions) that have a
                                 matching value in their
                                 ma-schedule-suppression-tags and all
                                 Actions that have a matching value in
                                 their ma-action-suppression-tags.
                                 Pattern matching is done using a glob
                                 style pattern (see below).

   ma-suppression-stop-running:  An optional boolean indicating whether
                                 Suppression will stop any running
                                 matching Schedules or Actions.  The
                                 default value for this boolean is
                                 false.

   Glob style pattern matching is following POSIX.2 fnmatch() [POSIX.2]
   without special treatment of file paths:

               *         matches a sequence of characters
               ?         matches a single character
               [seq]     matches any character in seq
               [!seq]    matches any character not in seq

   A backslash followed by a character matches the following character.
   In particular:

               \*        matches *
               \?        matches ?
               \\        matches \

   A sequence seq may be a sequence of characters (e.g., [abc]) or a
   range of characters (e.g., [a-c]).

4.4.  Logging Information

   The MA may report on the success or failure of Configuration or
   Instruction communications from the Controller.  In addition, further
   operational logs may be produced during the operation of the MA, and
   updates to Capabilities may also be reported.  Reporting this
   information is achieved in exactly the same manner as scheduling any
   other Task.  We make no distinction between a Measurement Task
   conducting an active or passive network measurement and one that
   solely retrieves static or dynamic information from the MA such as
   Capabilities or Logging Information.  One or more logging Tasks can
   be programmed or configured to capture subsets of the Logging
   Information.  These logging Tasks are then executed by Schedules,
   which also specify that the resultant data is to be transferred over
   the Controller Channels.

   The type of Logging Information will fall into three different
   categories:

   1.  Success/failure/warning messages in response to information
       updates from the Controller.  Failure messages could be produced
       due to some inability to receive or parse the Controller
       communication or if the MA is not able to act as instructed.  For
       example:

       *  "Measurement Schedules updated OK"

       *  "Unable to parse JSON"

       *  "Missing mandatory element: Measurement Timing"

       *  "'Start' does not conform to schema - expected datetime"

       *  "Date specified is in the past"

       *  "'Hour' must be in the range 1..24"

       *  "Schedule A refers to non-existent Measurement Task
          Configuration"

       *  "Measurement Task Configuration X registry, entry Y not found"

       *  "Updated Measurement Task Configurations do not include M used
          by Measurement Schedule N"

   2.  Operational updates from the MA.  For example:

       *  "Out of memory: cannot record result"

       *  "Collector 'collector.example.com' not responding"

       *  "Unexpected restart"

       *  "Suppression timeout"

       *  "Failed to execute Measurement Task Configuration H"

   3.  Status updates from the MA.  For example:

       *  "Device interface added: eth3"

       *  "Supported measurements updated"

       *  "New IP address on eth0: xxx.xxx.xxx.xxx"

   This Information Model document does not detail the precise format of
   Logging Information since it is to a large extent protocol and MA
   specific.  However, some common information can be identified.

4.4.1.  Definition of ma-log-obj

     object {
         uuid                ma-log-agent-id;
         datetime            ma-log-event-time;
         int                 ma-log-code;
         string              ma-log-description;
     } ma-log-obj;

   The ma-log-obj models the generic aspects of a logging object and
   consists of the following elements:

   ma-log-agent-id:          A uuid uniquely identifying the Measurement
                             Agent.

   ma-log-event-time:        The date and time of the Event reported in
                             the logging object.

   ma-log-code:              A machine-readable code describing the
                             Event.

   ma-log-description:       A human-readable description of the Event.

4.5.  Capability and Status Information

   The MA will hold Capability Information that can be retrieved by a
   Controller.  Capabilities include the device interface details
   available to Measurement Tasks as well as the set of Measurement
   Tasks/Roles (specified by registry entries) that are actually
   installed or available on the MA.  Status Information includes the
   times that operations were last performed such as contacting the
   Controller or producing Reports.

4.5.1.  Definition of ma-capability-obj

     object {
         string                  ma-capability-hardware;
         string                  ma-capability-firmware;
         string                  ma-capability-version;
        [string                  ma-capability-tags<0..*>;]
        [ma-capability-task-obj  ma-capability-tasks<0..*>;]
     } ma-capability-obj;

   The ma-capability-obj provides information about the Capabilities of
   the Measurement Agent and consists of the following elements:

   ma-capability-hardware:   A description of the hardware of the device
                             the Measurement Agent is running on.

   ma-capability-firmware:   A description of the firmware of the device
                             the Measurement Agent is running on.

   ma-capability-version:    The version of the Measurement Agent.

   ma-capability-tags:       An optional unordered set of tags that
                             provide additional information about the
                             Capabilities of the Measurement Agent.

   ma-capability-tasks:      An optional unordered set of capability
                             objects for each supported Task.

4.5.2.  Definition of ma-capability-task-obj

     object {
         string              ma-capability-task-name;
         ma-registry-obj     ma-capability-task-functions<0..*>;
         string              ma-capability-task-version;
     } ma-capability-task-obj;

   The ma-capability-task-obj provides information about the capability
   of a Task and consists of the following elements:

   ma-capability-task-name:        A name uniquely identifying a Task.

   ma-capability-task-functions:   A possibly empty unordered set of
                                   registry entries identifying
                                   functions this Task implements.

   ma-capability-task-version:     The version of the Measurement Task.

4.5.3.  Definition of ma-status-obj

     object {
         uuid                       ma-status-agent-id;
        [uri                        ma-status-device-id;]
         datetime                   ma-status-last-started;
         ma-status-interface-obj    ma-status-interfaces<0..*>;
        [ma-status-schedule-obj     ma-status-schedules<0..*>;]
        [ma-status-suppression-obj  ma-status-suppressions<0..*>;]
     } ma-status-obj;

   The ma-status-obj provides Status Information about the Measurement
   Agent and consists of the following elements:

   ma-status-agent-id:       A uuid uniquely identifying the Measurement
                             Agent.

   ma-status-device-id:      A URI identifying the device.

   ma-status-last-started:   The date and time the Measurement Agent
                             last started.

   ma-status-interfaces:     An unordered set of network interfaces
                             available on the device.

   ma-status-schedules:      An optional unordered set of status objects
                             for each Schedule.

   ma-status-suppressions:   An optional unordered set of status objects
                             for each Suppression.

4.5.4.  Definition of ma-status-schedule-obj

     object {
         string                  ma-status-schedule-name;
         string                  ma-status-schedule-state;
         int                     ma-status-schedule-storage;
         counter                 ma-status-schedule-invocations;
         counter                 ma-status-schedule-suppressions;
         counter                 ma-status-schedule-overlaps;
         counter                 ma-status-schedule-failures;
         datetime                ma-status-schedule-last-invocation;
        [ma-status-action-obj    ma-status-schedule-actions<0..*>;]
     } ma-status-schedule-obj;

   The ma-status-schedule-obj provides Status Information about the
   status of a Schedule and consists of the following elements:

   ma-status-schedule-name:            The name of the Schedule this
                                       status object refers to.

   ma-status-schedule-state:           The state of the Schedule.  The
                                       value 'enabled' indicates that
                                       the Schedule is currently
                                       enabled.  The value 'suppressed'
                                       indicates that the Schedule is
                                       currently suppressed.  The value
                                       'disabled' indicates that the
                                       Schedule is currently disabled.
                                       The value 'running' indicates
                                       that the Schedule is currently
                                       running.

   ma-status-schedule-storage:         The amount of secondary storage
                                       (e.g., allocated in a file
                                       system) holding temporary data
                                       allocated to the Schedule in
                                       bytes.  This object reports the
                                       amount of allocated physical
                                       storage and not the storage used
                                       by logical data records.  Data
                                       models should use a 64-bit
                                       integer type.

   ma-status-schedule-invocations      Number of invocations of this
                                       Schedule.  This counter does not
                                       include suppressed invocations or
                                       invocations that were prevented
                                       due to an overlap with a previous
                                       invocation of this Schedule.

   ma-status-schedule-suppressions     Number of suppressed executions
                                       of this Schedule.

   ma-status-schedule-overlaps         Number of executions prevented
                                       due to overlaps with a previous
                                       invocation of this Schedule.

   ma-status-schedule-failures         Number of failed executions of
                                       this Schedule.  A failed
                                       execution is an execution where
                                       at least one Action failed.

   ma-status-schedule-last-invocation: The date and time of the last
                                       invocation of this Schedule.

   ma-status-schedule-actions:         An optional ordered list of
                                       status objects for each Action of
                                       the Schedule.

4.5.5.  Definition of ma-status-action-obj

     object {
         string              ma-status-action-name;
         string              ma-status-action-state;
         int                 ma-status-action-storage;
         counter             ma-status-action-invocations;
         counter             ma-status-action-suppressions;
         counter             ma-status-action-overlaps;
         counter             ma-status-action-failures;
         datetime            ma-status-action-last-invocation;
         datetime            ma-status-action-last-completion;
         int                 ma-status-action-last-status;
         string              ma-status-action-last-message;
         datetime            ma-status-action-last-failed-completion;
         int                 ma-status-action-last-failed-status;
         string              ma-status-action-last-failed-message;
     } ma-status-action-obj;

   The ma-status-action-obj provides Status Information about an Action
   of a Schedule and consists of the following elements:

   ma-status-action-name:                   The name of the Action of a
                                            Schedule this status object
                                            refers to.

   ma-status-action-state:                  The state of the Action.
                                            The value 'enabled'
                                            indicates that the Action is
                                            currently enabled.  The
                                            value 'suppressed' indicates
                                            that the Action is currently
                                            suppressed.  The value
                                            'disabled' indicates that
                                            the Action is currently
                                            disabled.  The value
                                            'running' indicates that the
                                            Action is currently running.

   ma-status-action-storage:                The amount of secondary
                                            storage (e.g., allocated in
                                            a file system) holding
                                            temporary data allocated to
                                            the Action in bytes.  This
                                            object reports the amount of
                                            allocated physical storage
                                            and not the storage used by
                                            logical data records.  Data
                                            models should use a 64-bit
                                            integer type.

   ma-status-action-invocations             Number of invocations of
                                            this Action.  This counter
                                            does not include suppressed
                                            invocations or invocations
                                            that were prevented due to
                                            an overlap with a previous
                                            invocation of this Action.

   ma-status-action-suppressions            Number of suppressed
                                            executions of this Action.

   ma-status-action-overlaps                Number of executions
                                            prevented due to overlaps
                                            with a previous invocation
                                            of this Action.

   ma-status-action-failures                Number of failed executions
                                            of this Action.

   ma-status-action-last-invocation:        The date and time of the
                                            last invocation of this
                                            Action.

   ma-status-action-last-completion:        The date and time of the
                                            last completion of this
                                            Action.

   ma-status-action-last-status:            The status code returned by
                                            the last execution of this
                                            Action.

   ma-status-action-last-message:           The status message produced
                                            by the last execution of
                                            this Action.

   ma-status-action-last-failed-completion: The date and time of the
                                            last failed completion of
                                            this Action.

   ma-status-action-last-failed-status:     The status code returned by
                                            the last failed execution of
                                            this Action.

   ma-status-action-last-failed-message:    The status message produced
                                            by the last failed execution
                                            of this Action.

4.5.6.  Definition of ma-status-suppression-obj

     object {
         string                  ma-status-suppression-name;
         string                  ma-status-suppression-state;
     } ma-status-suppression-obj;

   The ma-status-suppression-obj provides Status Information about the
   status of a Suppression and consists of the following elements:

   ma-status-suppression-name:   The name of the Suppression this status
                                 object refers to.

   ma-status-suppression-state:  The state of the Suppression.  The
                                 value 'enabled' indicates that the
                                 Suppression is currently enabled.  The
                                 value 'active' indicates that the
                                 Suppression is currently active.  The
                                 value 'disabled' indicates that the
                                 Suppression is currently disabled.

4.5.7.  Definition of ma-status-interface-obj

     object {
         string              ma-status-interface-name;
         string              ma-status-interface-type;
        [int                 ma-status-interface-speed;]
        [string              ma-status-interface-link-layer-address;]
        [ip-address          ma-status-interface-ip-addresses<0..*>;]
        [ip-address          ma-status-interface-gateways<0..*>;]
        [ip-address          ma-status-interface-dns-servers<0..*>;]
     } ma-status-interface-obj;

   The ma-status-interface-obj provides Status Information about network
   interfaces and consists of the following elements:

   ma-status-interface-name:               A name uniquely identifying a
                                           network interface.

   ma-status-interface-type:               The type of the network
                                           interface.

   ma-status-interface-speed:              An optional indication of the
                                           speed of the interface
                                           (measured in bits per
                                           second).

   ma-status-interface-link-layer-address: An optional link-layer
                                           address of the interface.

   ma-status-interface-ip-addresses:       An optional ordered list of
                                           IP addresses assigned to the
                                           interface.

   ma-status-interface-gateways:           An optional ordered list of
                                           gateways assigned to the
                                           interface.

   ma-status-interface-dns-servers:        An optional ordered list of
                                           DNS servers assigned to the
                                           interface.

4.6.  Reporting Information

   At a point in time specified by a Schedule, the MA will execute Tasks
   that communicate a set of measurement results to the Collector.
   These Reporting Tasks will be configured to transmit Task results
   over a specified Report Channel to a Collector.

   It should be noted that the output from Tasks does not need to be
   sent to communication Channels.  It can alternatively, or
   additionally, be sent to other Tasks on the MA.  This facilitates
   using a first Measurement Task to control the operation of a later
   Measurement Task (such as first probing available line speed and then
   adjusting the operation of a video testing measurement) and also to
   allow local processing of data to output alarms (e.g., when
   performance drops from earlier levels).  Of course, subsequent Tasks
   also include Tasks that implement the Reporting Protocol(s) and
   transfer data to one or more Collectors.

   The Report generated by a Reporting Task is structured hierarchically
   to avoid repetition of report header and Measurement Task
   Configuration information.  The report starts with the timestamp of
   the report generation on the MA and details about the MA including
   the optional Measurement Agent Identifier and Group-ID (controlled by
   the Configuration Information).

   Much of the report information is optional and will depend on the
   implementation of the Reporting Task and any parameters defined in
   the Task Configuration for the Reporting Task.  For example, some
   Reporting Tasks may choose not to include the Measurement Task
   Configuration or Action parameters, while others may do so dependent
   on the Controller setting a configurable parameter in the Task
   Configuration.

   It is possible for a Reporting Task to send just the report header
   (datetime and optional Agent Identifier and/or Group-ID) if no
   measurement data is available.  Whether to send such empty reports
   again is dependent on the implementation of the Reporting Task and
   potential Task Configuration parameter.

   The handling of measurement data on the MA before generating a Report
   and transfer from the MA to the Collector is dependent on the
   implementation of the device, MA, and/or scheduled Tasks and not
   defined by the LMAP standards.  Such decisions may include limits to
   the measurement data storage and what to do when such available
   storage becomes depleted.  It is generally suggested that
   implementations running out of storage stop executing new Measurement
   Tasks and retain old measurement data.

   No context information, such as line speed or broadband product are
   included within the report header information as this data is
   reported by individual Tasks at the time they execute.  Either a
   Measurement Task can report contextual parameters that are relevant
   to that particular measurement or specific Tasks can be used to
   gather a set of contextual and environmental data at certain times
   independent of the Reporting Schedule.

   After the report header information, the results are reported grouped
   according to different Measurement Task Configurations.  Each Task
   section optionally starts with replicating the Measurement Task
   Configuration information before the result headers (titles for data
   columns) and the result data rows.  The Options reported are those
   used for the scheduled execution of the Measurement Task and
   therefore include the Options specified in the Task Configuration as
   well as additional Options specified in the Action.  The Action
   Options are appended to the Task Configuration Options in exactly the
   same order as they were provided to the Task during execution.

   The result row data includes a time for the start of the measurement
   and optionally an end time where the duration also needs to be
   considered in the data analysis.

   Some Measurement Tasks may optionally include an indication of the
   cross-traffic although the definition of cross-traffic is left up to
   each individual Measurement Task.  Some Measurement Tasks may also
   output other environmental measures in addition to cross-traffic such
   as CPU utilization or interface speed.

   Whereas the Configuration and Instruction Information represent
   information transmitted via the Control Protocol, the Report
   represents the information that is transmitted via the Report
   Protocol.  It is constructed at the time of sending a report and
   represents the inherent structure of the information that is sent to
   the Collector.

4.6.1.  Definition of ma-report-obj

     object {
         datetime              ma-report-date;
        [uuid                  ma-report-agent-id;]
        [string                ma-report-group-id;]
        [string                ma-report-measurement-point;]
        [ma-report-result-obj  ma-report-results<0..*>;]
     } ma-report-obj;

   The ma-report-obj provides the metadata of a single report and
   consists of the following elements:

   ma-report-date:               The date and time when the report was
                                 sent to a Collector.

   ma-report-agent-id:           An optional uuid uniquely identifying
                                 the Measurement Agent.

   ma-report-group-id:           An optional identifier of the group of
                                 Measurement Agents this Measurement
                                 Agent belongs to.

   ma-report-measurement-point:  An optional identifier for the
                                 measurement point indicating where the
                                 Measurement Agent is located on a path
                                 (see [RFC7398] for further details).

   ma-report-results:            An optional and possibly empty
                                 unordered set of result objects.

4.6.2.  Definition of ma-report-result-obj

     object {
         string                  ma-report-result-schedule-name;
         string                  ma-report-result-action-name;
         string                  ma-report-result-task-name;
        [ma-option-obj           ma-report-result-options<0..*>;]
        [string                  ma-report-result-tags<0..*>;]
         datetime                ma-report-result-event-time;
         datetime                ma-report-result-start-time;
        [datetime                ma-report-result-end-time;]
        [string                  ma-report-result-cycle-number;]
         int                     ma-report-result-status;
        [ma-report-conflict-obj  ma-report-result-conflicts<0..*>;]
        [ma-report-table-obj     ma-report-result-tables<0..*>;]
     } ma-report-result-obj;

   The ma-report-result-obj provides the metadata of a result report of
   a single executed Action.  It consists of the following elements:

   ma-report-result-schedule-name: The name of the Schedule that
                                   produced the result.

   ma-report-result-action-name:   The name of the Action in the
                                   Schedule that produced the result.

   ma-report-result-task-name:     The name of the Task that produced
                                   the result.

   ma-report-result-options:       An optional ordered joined list of
                                   options provided by the Task object
                                   and the Action object when the Action
                                   was started.

   ma-report-result-tags:          An optional unordered set of tags.
                                   This is the joined set of tags
                                   provided by the Task object, Action
                                   object, and Schedule object when the
                                   Action was started.

   ma-report-result-event-time:    The date and time of the Event that
                                   triggered the Schedule of the Action
                                   that produced the reported result
                                   values.  The date and time does not
                                   include any added randomization.

   ma-report-result-start-time:    The date and time of the start of the
                                   Action that produced the reported
                                   result values.

   ma-report-result-end-time:      An optional date and time indicating
                                   when the Action finished.

   ma-report-result-cycle-number:  An optional cycle number derived from
                                   ma-report-result-event-time.  It is
                                   the time closest to
                                   ma-report-result-event-time that is a
                                   multiple of the
                                   ma-event-cycle-interval of the Event
                                   that triggered the execution of the
                                   Schedule.  The value is only present
                                   in an ma-report-result-obj if the
                                   Event that triggered the execution of
                                   the Schedule has a defined
                                   ma-event-cycle-interval.  The cycle
                                   number is represented in the format
                                   YYYYMMDD.HHMMSS where YYYY represents
                                   the year, MM the month (1..12), DD
                                   the day of the months (01..31), HH
                                   the hour (00..23), MM the minute
                                   (00..59), and SS the second (00..59).
                                   The cycle number is using Coordinated
                                   Universal Time (UTC).

   ma-report-result-status:        The status code returned by the
                                   execution of the Action.

   ma-report-result-conflicts:     A possibly empty set of conflict
                                   Actions that might have impacted the
                                   measurement results being reported.

   ma-report-result-tables:        An optional and possibly empty
                                   unordered set of result tables.

4.6.3.  Definition of ma-report-conflict-obj

     object {
         string  ma-report-conflict-schedule-name;
         string  ma-report-conflict-action-name;
         string  ma-report-conflict-task-name;
     } ma-report-conflict-obj;

   The ma-report-conflict-obj provides the information about a
   conflicting Action that might have impacted the measurement results.
   It consists of the following elements:

   ma-report-result-schedule-name: The name of the Schedule that may
                                   have impacted the result.

   ma-report-result-action-name:   The name of the Action in the
                                   Schedule that may have impacted the
                                   result.

   ma-report-result-task-name:     The name of the Task that may have
                                   impacted the result.

4.6.4.  Definition of ma-report-table-obj

     object {
        [ma-registry-obj     ma-report-table-functions<0..*>;]
        [string]             ma-report-table-column-labels<0..*>;]
        [ma-report-row-obj   ma-report-table-rows<0..*>;]
     } ma-report-table-obj;

   The ma-report-table-obj represents a result table and consists of the
   following elements:

   ma-report-table-functions:      An optional and possibly empty
                                   unordered set of registry entries
                                   identifying the functions for which
                                   results are reported.

   ma-report-table-column-labels:  An optional and possibly empty
                                   ordered list of column labels.

   ma-report-table-rows:           A possibly empty ordered list of
                                   result rows.

4.6.5.  Definition of ma-report-row-obj

     object {
         data                ma-report-row-values<0..*>;
     } ma-report-row-obj;

   The ma-report-row-obj represents a result row and consists of the
   following elements:

   ma-report-row-values:     A possibly empty ordered list of result
                             values.  When present, it contains an
                             ordered list of values that align to the
                             set of column labels for the report.

4.7.  Common Objects: Schedules

   A Schedule specifies the execution of a single or repeated series of
   Actions.  An Action extends a configured Task with additional
   specific parameters.  Each Schedule contains basically two elements:
   an ordered list of Actions to be executed and an Event object
   triggering the execution of the Schedule.  The Schedule states what
   Actions to run (with what configuration) and when to run the Actions.
   A Schedule may optionally have an Event that stops the execution of
   the Schedule or a maximum duration after which a Schedule is stopped.

   Multiple Actions contained as an ordered list of a single Measurement
   Schedule will be executed according to the execution mode of the
   Schedule.  In sequential mode, Actions will be executed sequentially
   and in parallel mode, all Actions will be executed concurrently.  In
   pipelined mode, data produced by one Action is passed to the
   subsequent Action.  Actions contained in different Schedules execute
   in parallel with such conflicts being reported in the Reporting
   Information where necessary.  If two or more Schedules have the same
   start time, then the two will execute in parallel.  There is no
   mechanism to prioritize one Schedule over another or to mutex
   scheduled Tasks.

   As well as specifying which Actions to execute, the Schedule also
   specifies how to link the data outputs from each Action to other
   Schedules.  Specifying this within the Schedule allows the highest
   level of flexibility since it is even possible to send the output
   from different executions of the same Task Configuration to different
   destinations.  A single Task producing multiple different outputs is
   expected to properly tag the different results.  An Action receiving
   the output can then filter the results based on the tag if necessary.
   For example, a Measurement Task might report routine results to a
   data Reporting Task in a Schedule that communicates hourly via the
   broadband interface, but it also outputs emergency conditions via an
   alarm Reporting Task in a different Schedule communicating
   immediately over a General Packet Radio Service (GPRS) Channel.  Note
   that Task-to-Task data transfer is always specified in association
   with the scheduled execution of the sending Task -- there is no need
   for a corresponding input specification for the receiving Task.
   While it is likely that an MA implementation will use a queue
   mechanism between the Schedules or Actions, this Information Model
   does not mandate or define a queue.  The Information Model, however,
   reports the storage allocated to Schedules and Actions so that
   storage usage can be monitored.  Furthermore, it is recommended that
   MA implementations by default retain old data and stop the execution
   of new Measurement Tasks if the MA runs out of storage capacity.

   When specifying the Task to execute within the Schedule, i.e.,
   creating an Action, it is possible to add to the Option parameters.
   This allows the Task Configuration to determine the common
   characteristics of a Task, while selected parameters (e.g., the test
   target URL) are defined within as Option parameters of the Action in
   the Schedule.  A single Task's Configuration can even be used
   multiple times in the same Schedule with different additional
   parameters.  This allows for efficiency in creating and transferring
   the Instruction.  Note that the semantics of what happens if an
   Option is defined multiple times (in either the Task Configuration,
   the Action, or both) is not standardized and will depend upon the
   Task.  For example, some Tasks may legitimately take multiple values
   for a single parameter.

   Where Options are specified in both the Action and the Task
   Configuration, the Action Options are appended to those specified in
   the Task Configuration.

   Example:  An Action of a Schedule references a single Measurement
      Task Configuration for measuring UDP latency.  It specifies that
      results are to be sent to a Schedule with a Reporting Action.
      This Reporting Task of the Reporting Action is executed by a
      separate Schedule that specifies that it should run hourly at 5
      minutes past the hour.  When run, this Reporting Action takes the
      data generated by the UDP latency Measurement Task as well as any
      other data to be included in the hourly report and transfers it to
      the Collector over the Report Channel specified within its own
      Schedule.

   Schedules and Actions may optionally also be given tags that are
   included in result reports sent to a Collector.  In addition,
   Schedules can be given Suppression tags that may be used to select
   Schedules and Actions for Suppression.

4.7.1.  Definition of ma-schedule-obj

     object {
         string              ma-schedule-name;
         ma-event-obj        ma-schedule-start;
        [ma-event-obj        ma-schedule-end;]
        [int                 ma-schedule-duration;]
         ma-action-obj       ma-schedule-actions<0..*>;
         string              ma-schedule-execution-mode;
        [string              ma-schedule-tags<0..*>;]
        [string              ma-schedule-suppression-tags<0..*>;]
     } ma-schedule-obj;

   The ma-schedule-obj is the main scheduling object.  It consists of
   the following elements:

   ma-schedule-name:             A name uniquely identifying a
                                 scheduling object.

   ma-schedule-start:            An Event object indicating when the
                                 Schedule starts.

   ma-schedule-end:              An optional Event object controlling
                                 the forceful termination of scheduled
                                 Actions.  When the Event occurs, all
                                 Actions of the Schedule will be forced
                                 to terminate gracefully.

   ma-schedule-duration:         An optional duration in seconds for the
                                 Schedule.  All Actions of the Schedule
                                 will be forced to terminate gracefully
                                 after the duration number of seconds
                                 past the start of the Schedule.

   ma-schedule-actions:          A possibly empty ordered list of
                                 Actions to invoke when the Schedule
                                 starts.

   ma-schedule-execution-mode:   Indicates whether the Actions should be
                                 executed sequentially, in parallel, or
                                 in a pipelined mode (where data
                                 produced by one Action is passed to the
                                 subsequent Action).  The default
                                 execution mode is pipelined.

   ma-schedule-tags:             An optional unordered set of tags that
                                 are reported together with the
                                 measurement results to a Collector.

   ma-schedule-suppression-tags: An optional unordered set of
                                 Suppression tags that are used to
                                 select Schedules to be suppressed.

4.7.2.  Definition of ma-action-obj

     object {
         string              ma-action-name;
         string              ma-action-config-task-name;
        [ma-option-obj       ma-action-task-options<0..*>;]
        [string              ma-action-destinations<0..*>;]
        [string              ma-action-tags<0..*>;]
        [string              ma-action-suppression-tags<0..*>;]
      } ma-action-obj;

   The ma-action-obj models a Task together with its Schedule-specific
   Task Options and Destination Schedules.  It consists of the following
   elements:

   ma-action-name:               A name uniquely identifying an Action
                                 of a scheduling object.

   ma-action-config-task-name:   A name identifying the configured Task
                                 to be invoked by the Action.

   ma-action-task-options:       An optional and possibly empty ordered
                                 list of options (name-value pairs) that
                                 are passed to the Task by appending
                                 them to the options configured for the
                                 Task object.

   ma-action-destinations:       An optional and possibly empty
                                 unordered set of names of Destination
                                 Schedules that consume output produced
                                 by this Action.

   ma-action-tags:               An optional unordered set of tags that
                                 are reported together with the
                                 measurement results to a Collector.

   ma-action-suppression-tags:   An optional unordered set of
                                 Suppression tags that are used to
                                 select Actions to be suppressed.

4.8.  Common Objects: Channels

   A Channel defines a bidirectional communication mechanism between the
   MA and a Controller or Collector.  Multiple Channels can be defined
   to enable results to be split or duplicated across different
   Collectors.

   Each Channel contains the details of the remote endpoint (including
   location and security credential information such as a certificate).
   The timing of when to communicate over a Channel is specified by the
   Schedule, which executes the corresponding Control or Reporting Task.
   The certificate can be the digital certificate associated to the
   Fully Qualified Domain Name (FQDN) in the URL, or it can be the
   certificate of the Certification Authority that was used to issue the
   certificate for the FQDN of the target URL (which will be retrieved
   later on using a communication protocol such as Transport Layer
   Security (TLS)).  In order to establish a secure Channel, the MA will
   use its own security credentials (in the Configuration Information)
   and the given credentials for the individual Channel endpoint.

   As with the Task Configurations, each Channel is also given a text
   name by which it can be referenced as a Task Option.

   Although the same in terms of information, Channels used for
   communication with the Controller are referred to as Control Channels
   whereas Channels to Collectors are referred to as Report Channels.
   Hence, Control Channels will be referenced from Control Tasks
   executed by a Control Schedule, whereas Report Channels will be
   referenced from within Reporting Tasks executed by an Instruction
   Schedule.

   Multiple interfaces are also supported.  For example, the Reporting
   Task could be configured to send some results over GPRS.  This is
   especially useful when such results indicate the loss of connectivity
   on a different network interface.

   Example:  A Channel used for reporting results may specify that
      results are to be sent to the URL (https://collector.example.org/
      report/), using the appropriate digital certificate to establish a
      secure Channel.

4.8.1.  Definition of ma-channel-obj

     object {
         string              ma-channel-name;
         url                 ma-channel-target;
         credentials         ma-channel-credentials;
         [string             ma-channel-interface-name;]
     } ma-channel-obj;

   The ma-channel-obj consists of the following elements:

   ma-channel-name:            A unique name identifying the Channel
                               object.

   ma-channel-target:          A URL identifying the target Channel
                               endpoint.

   ma-channel-credentials:     The security credentials needed to
                               establish a secure Channel.

   ma-channel-interface-name:  An optional name of the network interface
                               to be used.  If not present, the IP
                               protocol stack will select a suitable
                               interface.

4.9.  Common Objects: Task Configurations

   Conceptually, each Task Configuration defines the parameters of a
   Task that the MA may perform at some point in time.  It does not by
   itself actually instruct the MA to perform them at any particular
   time (this is done by a Schedule).  Tasks can be Measurement Tasks
   (i.e., those Tasks actually performing some type of passive or active
   measurement) or any other scheduled activity performed by the MA such
   as transferring information to or from the Controller and Collectors.
   Other examples of Tasks may include data manipulation or processing
   Tasks conducted on the MA.

   A Measurement Task Configuration is the same in information terms to
   any other Task Configuration.  Both Measurement and non-Measurement
   Tasks may have registry entries to enable the MA to uniquely identify
   the Task it should execute and retrieve the schema for any parameters
   that may be passed to the Task.  Registry entries are specified as a
   URI and can therefore be used to identify the Task within a namespace
   or point to a web or local file location for the Task information.
   As mentioned previously, these URIs may be used to identify the
   Measurement Task in a public namespace such as the to-be-created IPPM
   registry described in [IPPM-REG].

   Example:  A Measurement Task Configuration may configure a single
      Measurement Task for measuring UDP latency.  The Measurement Task
      Configuration could define the destination port and address for
      the measurement as well as the duration, internal packet timing
      strategy, and other parameters (for example, a stream for one hour
      and sending one packet every 500 ms).  It may also define the
      output type and possible parameters (for example, the output type
      can be the 95th percentile mean) where the Measurement Task
      accepts such parameters.  It does not define when the Task starts
      (this is defined by the Schedule element), so it does not by
      itself instruct the MA to actually perform this Measurement Task.

   The Task Configuration will include a local short name for reference
   by a Schedule.  Task Configurations may also refer to registry
   entries as described above.  In addition, the Task can be configured
   through a set of configuration Options.  The nature and number of
   these Options will depend upon the Task.  These Options are expressed
   as name-value pairs, although the 'value' may be a structured object
   instead of a simple string or numeric value.  The implementation of
   these name-value pairs will vary between data models.

   An Option that must be present for Reporting Tasks is the Channel
   reference specifying how to communicate with a Collector.  This is
   included in the Task Options and will have a value that matches a
   Channel name that has been defined in the Instruction.  Similarly,
   Control Tasks will have a similar Option with the value set to a
   specified Control Channel.

   A Reporting Task might also have a flag parameter, defined as an
   Option, to indicate whether to send a report without measurement
   results if there is no measurement result data pending to be
   transferred to the Collector.  In addition, many Tasks will receive
   (as a parameter) information about which interface to use.

   In addition, the Task Configuration may optionally also be given tags
   that can carry a Measurement Cycle ID.  The purpose of this ID is to
   easily identify a set of measurement results that have been produced
   by Measurement Tasks with comparable Options.  This ID could be
   manually incremented or otherwise changed when an Option change is
   implemented, which could mean that two sets of results should not be
   directly compared.

4.9.1.  Definition of ma-task-obj

     object {
         string              ma-task-name;
         ma-registry-obj     ma-task-functions<0..*>;
        [ma-option-obj       ma-task-options<0..*>;]
        [string              ma-task-tags<0..*>;]
     } ma-task-obj;

   The ma-task-obj defines a configured Task that can be invoked as part
   of an Action.  A configured Task can be referenced by its name, and
   it contains a possibly empty set of URIs to link to registry entries.
   Options allow the configuration of Task parameters (in the form of
   name-value pairs).  The ma-task-obj consists of the following
   elements:

   ma-task-name:             A name uniquely identifying a configured
                             Task object.

   ma-task-functions:        A possibly empty unordered set of registry
                             entries identifying the functions of the
                             configured Task.

   ma-task-options:          An optional and possibly empty ordered list
                             of options (name-value pairs) that are
                             passed to the configured Task.

   ma-task-tags:             An optional unordered set of tags that are
                             reported together with the measurement
                             results to a Collector.

4.9.2.  Definition of ma-option-obj

     object {
         string              ma-option-name;
        [object              ma-option-value;]
     } ma-option-obj;

   The ma-option-obj models a name-value pair and consists of the
   following elements:

   ma-option-name:           The name of the option.

   ma-option-value:          The optional value of the option.

   The ma-option-obj is used to define Task Configuration Options.  Task
   Configuration Options are generally Task specific.  For Tasks
   associated with an entry in a registry, the registry may define well-
   known option names (e.g., the so-called parameters in the to-be-
   created IPPM metric registry described in [IPPM-REG]).  Control and
   Reporting Tasks need to know the Channel they are going to use.  The
   common option name for specifying the Channel is "channel" where the
   option's value refers to the name of an ma-channel-obj.

4.10.  Common Objects: Registry Information

   Tasks and Actions can be associated with entries in a registry.  A
   registry object refers to an entry in a registry (identified by a
   URI), and it may define a set of roles.

4.10.1.  Definition of ma-registry-obj

     object {
         uri                 ma-registry-uri;
        [string              ma-registry-role<0..*>;]
     } ma-registry-obj;

   The ma-registry-obj refers to an entry of a registry, and it defines
   the associated role(s).  The ma-registry-obj consists of the
   following elements:

   ma-registry-uri:          A URI identifying an entry in a registry.

   ma-registry-role:         An optional and possibly empty unordered
                             set of roles for the identified registry
                             entry.

4.11.  Common Objects: Event Information

   The Event information object used throughout the Information Models
   can initially take one of several different forms.  Additional forms
   may be defined later in order to bind the execution of Schedules to
   additional Events.  The initially defined Event forms are:

   1.  Periodic Timing: Emits multiple Events periodically according to
       an interval time defined in seconds

   2.  Calendar Timing: Emits multiple Events according to a calendar-
       based pattern, e.g., 22 minutes past each hour of the day on
       weekdays

   3.  One-Off Timing: Emits one Event at a specific date and time

   4.  Immediate: Emits one Event as soon as possible

   5.  Startup: Emits an Event whenever the MA is started (e.g., at
       device startup)

   6.  Controller Lost: Emits an Event when connectivity to the
       Controller has been lost

   7.  Controller Connected: Emits an Event when connectivity to the
       Controller has been established or re-established

   Optionally, each of the Event options may also specify a randomness
   that should be evaluated and applied separately to each indicated
   Event.  This randomness parameter defines a uniform interval in
   seconds over which the start of the Task is delayed from the starting
   times specified by the Event object.

   Both the periodic and calendar timing objects allow for a series of
   Actions to be executed.  While both have an optional end time, it is
   best practice to always configure an end time and refresh the
   information periodically to ensure that lost MAs do not continue
   their Tasks forever.

   Startup Events are only created on device startup, not when a new
   Instruction is transferred to the MA.  If scheduled Task execution is
   desired both on the transfer of the Instruction and on device
   restart, then both the Immediate and Startup timing needs to be used
   in conjunction.

   The datetime format used for all elements in the Information Model
   MUST conform to RFC 3339 [RFC3339].

4.11.1.  Definition of ma-event-obj

     object {
        string               ma-event-name;
        union {
            ma-periodic-obj             ma-event-periodic;
            ma-calendar-obj             ma-event-calendar;
            ma-one-off-obj              ma-event-one-off;
            ma-immediate-obj            ma-event-immediate;
            ma-startup-obj              ma-event-startup;
            ma-controller-lost-obj      ma-event-controller-lost;
            ma-controller-connected-obj ma-event-controller-connected;
        }
        [int                 ma-event-random-spread;]
        [int                 ma-event-cycle-interval;]
     } ma-event-obj;

   The ma-event-obj is the main Event object.  Event objects are
   identified by a name.  A generic Event object itself contains a more
   specific Event object.  The set of specific Event objects should be
   extensible.  The initial set of specific Event objects is further
   described below.  The ma-event-obj also includes an optional uniform
   random spread that can be used to randomize the start times of
   Schedules triggered by an Event.  The ma-event-obj consists of the
   following elements:

   ma-event-name:                  The name uniquely identifies an Event
                                   object.  Schedules refer to Event
                                   objects by this name.

   ma-event-periodic:              The ma-event-periodic is present for
                                   periodic timing objects.

   ma-event-calendar:              The ma-event-calendar is present for
                                   calendar timing objects.

   ma-event-one-off:               The ma-event-one-off is present for
                                   one-off timing objects.

   ma-event-immediate:             The ma-event-immediate is present for
                                   immediate Event objects.

   ma-event-startup:               The ma-event-startup is present for
                                   startup Event objects.

   ma-event-controller-lost:       The ma-event-controller-lost is
                                   present for connectivity to
                                   Controller lost Event objects.

   ma-event-controller-connected:  The ma-event-controller-connected is
                                   present for connectivity to
                                   Controller established Event objects.

   ma-event-random-spread:         The optional ma-event-random-spread
                                   adds a random delay defined in
                                   seconds to the Event object.  No
                                   random delay is added if
                                   ma-event-random-spread does not
                                   exist.

   ma-event-cycle-interval:        The optional ma-event-cycle-interval
                                   defines the duration of the time
                                   interval in seconds that is used to
                                   calculate cycle numbers.  No cycle
                                   number is calculated if
                                   ma-event-cycle-interval does not
                                   exist.

4.11.2.  Definition of ma-periodic-obj

     object {
        [datetime            ma-periodic-start;]
        [datetime            ma-periodic-end;]
         int                 ma-periodic-interval;
     } ma-periodic-obj;

   The ma-periodic-obj timing object has an optional start and an
   optional end time plus a periodic interval.  Schedules using an
   ma-periodic-obj are started periodically between the start and end
   time.  The ma-periodic-obj consists of the following elements:

   ma-periodic-start:        The optional date and time at which
                             Schedules using this object are first
                             started.  If not present, it defaults to
                             immediate.

   ma-periodic-end:          The optional date and time at which
                             Schedules using this object are last
                             started.  If not present, it defaults to
                             indefinite.

   ma-periodic-interval:     The interval defines the time in seconds
                             between two consecutive starts of Tasks.

4.11.3.  Definition of ma-calendar-obj

   Calendar timing supports the routine execution of Schedules at
   specific times and/or on specific dates.  It can support more
   flexible timing than periodic timing since the execution of Schedules
   does not have to be uniformly spaced.  For example, a calendar timing
   could support the execution of a Measurement Task every hour between
   6 pm and midnight on weekdays only.

   Calendar timing is also required to perform measurements at
   meaningful times in relation to network usage (e.g., at peak times).
   If the optional time zone offset is not supplied, then local system
   time is assumed.  This is essential in some use cases to ensure
   consistent peak-time measurements as well as supporting MA devices
   that may be in an unknown time zone or to roam between different time
   zones (but know their own time zone information such as through the
   mobile network).

   The calendar elements within the calendar timing do not have defaults
   in order to avoid accidental high-frequency execution of Tasks.  If
   all possible values for an element are desired, then the wildcard *
   is used.

     object {
        [datetime            ma-calendar-start;]
        [datetime            ma-calendar-end;]
        [string              ma-calendar-months<0..*>;]
        [string              ma-calendar-days-of-week<0..*>;]
        [string              ma-calendar-days-of-month<0..*>;]
        [string              ma-calendar-hours<0..*>;]
        [string              ma-calendar-minutes<0..*>;]
        [string              ma-calendar-seconds<0..*>;]
        [int                 ma-calendar-timezone-offset;]
     } ma-calendar-obj;

   ma-calendar-start:            The optional date and time at which
                                 Schedules using this object are first
                                 started.  If not present, it defaults
                                 to immediate.

   ma-calendar-end:              The optional date and time at which
                                 Schedules using this object are last
                                 started.  If not present, it defaults
                                 to indefinite.

   ma-calendar-months:           The optional set of months (1-12) on
                                 which Tasks scheduled using this object
                                 are started.  The wildcard * means all
                                 months.  If not present, it defaults to
                                 no months.

   ma-calendar-days-of-week:     The optional set of days of a week
                                 ("Mon", "Tue", "Wed", "Thu", "Fri",
                                 "Sat", "Sun") on which Tasks scheduled
                                 using this object are started.  The
                                 wildcard * means all days of the week.
                                 If not present, it defaults to no days.

   ma-calendar-days-of-month:    The optional set of days of a month
                                 (1-31) on which Tasks scheduled using
                                 this object are started.  The wildcard
                                 * means all days of a month.  If not
                                 present, it defaults to no days.

   ma-calendar-hours:            The optional set of hours (0-23) on
                                 which Tasks scheduled using this object
                                 are started.  The wildcard * means all
                                 hours of a day.  If not present, it
                                 defaults to no hours.

   ma-calendar-minutes:          The optional set of minutes (0-59) on
                                 which Tasks scheduled using this object
                                 are started.  The wildcard * means all
                                 minutes of an hour.  If not present, it
                                 defaults to no minutes.

   ma-calendar-seconds:          The optional set of seconds (0-59) on
                                 which Tasks scheduled using this object
                                 are started.  The wildcard * means all
                                 seconds of an hour.  If not present, it
                                 defaults to no seconds.

   ma-calendar-timezone-offset:  The optional time zone offset in
                                 minutes.  If not present, it defaults
                                 to the system's local time zone.

   If a day of the month is specified that does not exist in the month
   (e.g., the 29th of February), then those values are ignored.

4.11.4.  Definition of ma-one-off-obj

     object {
         datetime            ma-one-off-time;
     } ma-one-off-obj;

   The ma-one-off-obj timing object specifies a fixed point in time.
   Schedules using an ma-one-off-obj are started once at the specified
   date and time.  The ma-one-off-obj consists of the following
   elements:

   ma-one-off-time:          The date and time at which Schedules using
                             this object are started.

4.11.5.  Definition of ma-immediate-obj

     object {
                             // empty
     } ma-immediate-obj;

   The ma-immediate-obj Event object has no further information
   elements.  Schedules using an ma-immediate-obj are started as soon as
   possible.

4.11.6.  Definition of ma-startup-obj

     object {
                             // empty
     } ma-startup-obj;

   The ma-startup-obj Event object has no further information elements.
   Schedules or Suppressions using an ma-startup-obj are started at MA
   initialization time.

4.11.7.  Definition of ma-controller-lost-obj

     object {
                             // empty
     } ma-controller-lost-obj;

   The ma-controller-lost-obj Event object has no further information
   elements.  The ma-controller-lost-obj indicates that connectivity to
   the Controller has been lost.  This is determined by a timer started
   after each successful contact with a Controller.  When the timer
   reaches the controller-timeout (measured in seconds), a
   ma-controller-lost-obj Event is generated.  This Event may be used to
   start a Suppression.

4.11.8.  Definition of ma-controller-connected-obj

     object {
                             // empty
     } ma-controller-connected-obj;

   The ma-controller-connected-obj Event object has no further
   information elements.  The ma-controller-connected-obj indicates that
   connectivity to the Controller has been established again after it
   was lost.  This Event may be used to end a Suppression.

5.  Example Execution

   The example execution has two Event sources, E1 and E2, and three
   Schedules, S1, S2, and S3.  The Schedule S3 is started by Events of
   Event source E2 while the Schedules S1 and S2 are both started by
   Events of the Event source E1.  The Schedules S1 and S2 have two
   Actions each, and Schedule S3 has a single Action.  The Event source
   E2 has no randomization while the Event source E1 has the
   randomization r.

   Figure 2 shows a possible timeline of an execution.  The time T is
   progressing downwards.  The dotted vertical line indicates progress
   of time while a dotted horizontal line indicates which Schedules are
   triggered by an Event.  Lines of tildes indicate data flowing from an
   Action to another Schedule.  Actions within a Schedule are named A1,
   A2, etc.

     E2    E1   T           S1           S2            S3
                        sequential    parallel     pipelined
                :
             e0 +
                :
                :
           e0+r + .......... + .......... ++
                :            | A1      A1 || A2
                :            +            |+ ~~~~~~~>
                :            | A2         |
                :            |            + ~~~~~~~~>
                :            + ~~~~~~~~~~~~~~~~~~~~~>
                :
                :
             e1 +
                :
           e1+r + .......... + .......... ++
                :            | A1      A1 ||
                :            |            +|~~~~~~~>
                :            |             | A2
                :            +             +~~~~~~~>
                :            | A2
                :            + ~~~~~~~~~~~~~~~~~~~~>
      e0        + ................................... +
                :                                     | A1
             e3 +                                     |
           e3+r + .......... + .......... ++          |
                :            | A1      A1 || A2       |
                :            +            ++ ~~~~~~>  |
                :            | A2                     +
                :            + ~~~~~~~~~~~~~~~~~~~~>
                V

                        Figure 2: Example Execution

   Note that implementations must handle possible concurrency issues.
   In the example execution, Action A1 of Schedule S3 is consuming the
   data that has been forwarded to Schedule S3 while additional data is
   arriving from Action A2 of Schedule S2.

6.  IANA Considerations

   This document does not require any IANA actions.

7.  Security Considerations

   This Information Model deals with information about the control and
   reporting of the Measurement Agent.  There are broadly two security
   considerations for such an Information Model.  Firstly, the
   Information Model has to be sufficient to establish secure
   communication Channels to the Controller and Collector such that
   other information can be sent and received securely.  Additionally,
   any mechanisms that the Network Operator or other device
   administrator employs to preconfigure the MA must also be secure to
   protect unauthorized parties from modifying Preconfiguration
   Information.  These mechanisms are important to ensure that the MA
   cannot be hijacked, for example, to participate in a distributed
   denial-of-service attack.

   The second consideration is that no mandated information items should
   pose a risk to confidentiality or privacy given such secure
   communication Channels.  For this latter reason, items such as the MA
   context and MA-ID are left optional and can be excluded from some
   deployments.  This may, for example, allow the MA to remain anonymous
   and for information about location or other context that might be
   used to identify or track the MA to be omitted or blurred.
   Implementations and deployments should also be careful about exposing
   device-ids when this is not strictly needed.

   An implementation of this Information Model should support all the
   security and privacy requirements associated with the LMAP Framework
   [RFC7594].  In addition, users of this Information Model are advised
   to choose identifiers for Group-IDs, tags, or names of Information
   Model objects (e.g., configured Tasks, Schedules, or Actions) that do
   not reveal any sensitive information to people authorized to process
   measurement results but who are not authorized to know details about
   the Measurement Agents that were used to perform the measurement.

8.  References

8.1.  Normative References

   [ISO.10646]
              International Organization for Standardization,
              "Information Technology - Universal Coded Character Set
              (UCS)", ISO Standard 10646:2014, September 2014.

   [POSIX.2]  The Open Group, "Standard for Information Technology -
              Portable Operating System Interface (POSIX(R)) Base
              Specifications, Issue 7", IEEE Standard 1003.1, 2016
              Edition, DOI, 10.1109/IEEESTD.2016.7582338, September
              2016.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC3339]  Klyne, G. and C. Newman, "Date and Time on the Internet:
              Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002,
              <https://www.rfc-editor.org/info/rfc3339>.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, DOI 10.17487/RFC3986, January 2005,
              <https://www.rfc-editor.org/info/rfc3986>.

   [RFC4122]  Leach, P., Mealling, M., and R. Salz, "A Universally
              Unique IDentifier (UUID) URN Namespace", RFC 4122,
              DOI 10.17487/RFC4122, July 2005,
              <https://www.rfc-editor.org/info/rfc4122>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

8.2.  Informative References

   [IPPM-REG]
              Bagnulo, M., Claise, B., Eardley, P., Morton, A., and A.
              Akhter, "Registry for Performance Metrics", Work in
              Progress, draft-ietf-ippm-metric-registry-12, June 2017.

   [RFC3444]  Pras, A. and J. Schoenwaelder, "On the Difference between
              Information Models and Data Models", RFC 3444,
              DOI 10.17487/RFC3444, January 2003,
              <https://www.rfc-editor.org/info/rfc3444>.

   [RFC7398]  Bagnulo, M., Burbridge, T., Crawford, S., Eardley, P., and
              A. Morton, "A Reference Path and Measurement Points for
              Large-Scale Measurement of Broadband Performance",
              RFC 7398, DOI 10.17487/RFC7398, February 2015,
              <https://www.rfc-editor.org/info/rfc7398>.

   [RFC7536]  Linsner, M., Eardley, P., Burbridge, T., and F. Sorensen,
              "Large-Scale Broadband Measurement Use Cases", RFC 7536,
              DOI 10.17487/RFC7536, May 2015,
              <https://www.rfc-editor.org/info/rfc7536>.

   [RFC7594]  Eardley, P., Morton, A., Bagnulo, M., Burbridge, T.,
              Aitken, P., and A. Akhter, "A Framework for Large-Scale
              Measurement of Broadband Performance (LMAP)", RFC 7594,
              DOI 10.17487/RFC7594, September 2015,
              <https://www.rfc-editor.org/info/rfc7594>.

   [RFC8194]  Schoenwaelder, J. and V. Bajpai, "A YANG Data Model for
              LMAP Measurement Agents", RFC 8194, DOI 10.17487/RFC8194,
              August 2017, <http://www.rfc-editor.org/info/rfc8194>.

Acknowledgements

   Several people contributed to this specification by reviewing early
   draft versions and actively participating in the LMAP Working Group
   (apologies to those unintentionally omitted): Vaibhav Bajpai, Michael
   Bugenhagen, Timothy Carey, Alissa Cooper, Kenneth Ko, Al Morton, Dan
   Romascanu, Henning Schulzrinne, Andrea Soppera, Barbara Stark, and
   Jason Weil.

   Marcelo Bagnulo, Trevor Burbridge, Philip Eardley, and Juergen
   Schoenwaelder worked in part on the Leone research project, which
   received funding from the European Union Seventh Framework Programme
   [FP7/2007-2013] under grant agreement number 317647.

   Juergen Schoenwaelder was partly funded by Flamingo, a Network of
   Excellence project (ICT-318488) supported by the European Commission
   under its Seventh Framework Programme.

Authors' Addresses

   Trevor Burbridge
   BT
   Adastral Park, Martlesham Heath
   Ipswich  IP5 3RE
   United Kingdom

   Email: trevor.burbridge@bt.com


   Philip Eardley
   BT
   Adastral Park, Martlesham Heath
   Ipswich  IP5 3RE
   United Kingdom

   Email: philip.eardley@bt.com


   Marcelo Bagnulo
   Universidad Carlos III de Madrid
   Av. Universidad 30
   Leganes, Madrid  28911
   Spain

   Email: marcelo@it.uc3m.es


   Juergen Schoenwaelder
   Jacobs University Bremen
   Campus Ring 1
   Bremen  28759
   Germany

   Email: j.schoenwaelder@jacobs-university.de

