Network Working Group S.E. Kille
INTERNET--DRAFT University College London
March 1991
Handling QOS (Quality of service) in the Directory
Status of this Memo
This document describes a mechanism for specifying the Quality of
Service for DSA Operations and Data in the Internet Pilot Directory
Service [Kil90].
This draft document will be submitted to the RFC editor as a
protocol specification. Distribution of this memo is unlimited.
Please send comments to the author or to the discussion group
<osi-ds@CS.UCL.AC.UK>.
INTERNET--DRAFT QOS in the Directory March 1991
1 Introduction
There have been a lot of problems with the variable quality of data
and service over the directory. These attributes are proposed for
use in the overall pilot (not implementation specific). In order
that these attributes may be useful, it will be necessary to ensure
that they are used throughout the pilot. For this reason, this
specification is being made into a protocol standard. The usage of
these attributes will be registered in the Cosine and Internet
X.500 Sechema [BK91]. The QOS definitions can be used in the
following ways:
1. By a user as additional information
2. By a system manager to determine what course of action to take
following operational problems
3. By a DSA, as a heuristic to improve distributed operation (DSA
choice)
4. By a DUA, perhaps to hide experimental stuff, or to indicate
the quality of data/service to the user
Parameters are given encoded values to facilitate automatic
processing, and string values as it is recognised that useful
subtleties of service can be indicated which are useful to the end
user (e.g., as to which aspects of the data can be trusted)
2 DSA Controls
The following attributes should be mandatory in the entry in the
DIT which represents each pilot DSA. When information in the DIT is
of high quality, it should be stored in DSAs of an appropriate
service level.
DSAQuality ATTRIBUTE
WITH ATTRIBUTE-SYNTAX DSAQualitySyntax
SINGLE VALUE
DSAQualitySyntax ::= SEQUENCE -
serviceQuality ENUMERATED -
defunct(0), -- not present
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INTERNET--DRAFT QOS in the Directory March 1991
experimental (1), -- unlikely to be present
best-effort (2), -- no guaranteed support
pilot-service (3), -- aim for >90% availability
full-service (4) -- expect >95% availability -- ",
description PrintableString OPTIONAL "
3 DIT Controls
The following attributes are defined, and should be present in
every non-leaf entry in the DIT. If it is not present, the value of
the attributes in the parent entry are assumed.
QualityLabelledData OBJECT-CLASS
SUBCLASS OF top
MUST CONTAIN -SingleLevelQuality"
MAY CONTAIN -SubtreeMinimumQuality,
SubtreeMaximumQuality"
SingleLevelQuality ATTRIBUTE
WITH ATTRIBUTE-SYNTAX DataQualitySyntax
SINGLE VALUE
-- Note that Subtree quality excludes the entries at the first level
-- It summarises the quality attributes at the levels below
SubtreeMaximumQuality ATTRIBUTE
WITH ATTRIBUTE-SYNTAX DataQualitySyntax
SINGLE VALUE
-- Defaults to SingleLevelQuality
SubtreeMinimumQuality ATTRIBUTE
WITH ATTRIBUTE-SYNTAX DataQualitySyntax
SINGLE VALUE
-- Defaults to SingleLevelQuality
DataQualitySyntax ::= SEQUENCE -
namespace-completeness Completeness,
defaultAttributeQuality AttributeQuality,
attributeQuality SET OF SEQUENCE -
AttributeType,
AttributeQuality ",
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INTERNET--DRAFT QOS in the Directory March 1991
description PrintableString OPTIONAL "
Completeness ::= ENUMERATED -
none(1),
sample(2), -- small number present at random
selected(3), -- partial coverage with most significant
-- values present
substantial(4), -- >80% coverage
full(5) -- all values present
",
AttributeQuality ::= SEQUENCE -
maintenance-level ENUMERATED -
unknown(1),
-- may be suspect
external(2),
-- downloaded from external source
-- of variable quality
system-maintained(3),
-- if there is a value, it will
-- be present and reasonably
-- accurate
user-supplied(4) "
attribute-completeness DEFAULT full "
The SingleLevelQuality attribute refers to the entries one level
below. Where there are further levels, the other two attributes
give an indication of the spectrum of quality of data in the lower
levels.
The quality of the data indicates both its coverage (of the entries
named), and the quality of attributes within the entries.
Note: It might be appropriate to measure data quality on the basis
of object classes at the level below. Comments are solicited
about this increase in complexity.
References
[BK91] P. Barker and S.E. Kille. The COSINE and Internet X.500
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INTERNET--DRAFT QOS in the Directory March 1991
schema, March 1991. Internet Draft:
draft-ietf-osids-cosinex500-02.txt.
[Kil90] S.E. Kille. Building and internet directory using X.500,
November 1990. Internet Draft:
draft-ietf-osix500-directories-01.txt.
4 Security Considerations
Security considerations are not discussed in this INTERNET--DRAFT .
5 Author's Address
Steve Kille
Department of Computer Science
University College London
Gower Street
WC1E 6BT
England
Phone: +44-71-380-7294
EMail: S.Kille@CS.UCL.AC.UK
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