LDAPv2 Client vs. the Index Mesh
draft-ietf-find-cip-ldapv2-02
The information below is for an old version of the document that is already published as an RFC.
Document | Type |
This is an older version of an Internet-Draft that was ultimately published as RFC 2657.
|
|
---|---|---|---|
Author | Roland Hedberg | ||
Last updated | 2013-03-02 (Latest revision 1998-12-28) | ||
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Intended RFC status | Experimental | ||
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draft-ietf-find-cip-ldapv2-02
FIND Working Group Roland Hedberg
Internet-Draft Catalogix
Expires in six month November 9, 1998
LDAPv2 client Vs the Index Mesh
<draft-ietf-find-cip-ldapv2-02.txt>
Status of this Memo
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Distribution of this memo is unlimited. Editorial comments should
be sent to the author (Roland.Hedberg@umdac.umu.se). Technical
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Abstract
Since LDAP v2 clients implemented according to RFC 1777 [1] has no
notion on referral. The integration between such a client and
a Index mesh, as defined by the current Common Indexing Protocol
draft [2], who heavily depends on referrals has to be handled
in a somewhat special way. This document defines one possible
way of doing this.
1. Background
During the development work with the Common Indexing protocol
(CIP)one of the underlying assumptions has been that the
interaction between clients and the Index Mesh Servers [1] would
heavily depend on passing of referrals. Protocols like LDAPv2 [2]
who lack this functionality has to compensate for it by some means.
The way chosen in this draft is to put some more intelligence
into the client. The reasoning behind this being first that it is
not a major enhancement that is needed and secondly that the
intelligence when dealing with the Index Mesh, with or the
knowledge about referrals, eventually has to go into the client.
2. The clients view of the Index Mesh
If a LDAP v2 client is going to be able to interact with
the Index Mesh, the Mesh has to appear as something that is
understandable to the client.
Basicly this consists of representing the index servers and their
contained indexes in a defined directory informations tree (DIT)
[3,4] structure and a set of object classes and attribute types that
has been proven to be useful in this contex.
2.1 The CIP Object Classes
Object class descriptions are written according to the BNF defined
in [5].
2.1.1 cIPIndex
The cIPIndex objectClass, if present in a entry, allowes it to
holds one indexvalue and information connected to this value.
( 1.2.752.17.3.9
NAME 'cIPIndex'
SUP 'top'
STRUCTURAL
MUST ( extendedDSI $ idx )
MAY ( indexOCAT )
)
2.1.2 cIPDataSet
The cIPDataSet objectClass, if present in a entry, allowes it to
hold information concerning one DataSet.
( 1.2.752.17.3.10
NAME 'cIPDataSet'
SUP 'top'
STRUCTURAL
MUST ( dSI $ searchBase )
MAY ( indexOCAT $ description $ indexType $
accessPoint $ protocolVersion $ polledBy $
updateIntervall $ securityOption $
supplierURI $ consumerURI $ baseURI $
attributeNamespace $ consistencyBase
)
)
2.2 The CIP attributeTypes
The attributes idx, indexOCAT, extendedDSI, description,
cIPIndexType, baseURI, dSI are used by a client acessing the
index server.
The other attributes ( accesspoint, protocolVersion, polledBy,
updateIntervall, consumerURI, supplierURI and securityOption,
attributeNamespace, consistencyBase) are all for usage in server
to server interactions.
2.2.1 idx
The index value, normally used as or part of the RDN.
( 1.2.752.17.1.20
NAME 'idx'
EQUALITY caseIgnoreIA5Match
SYNTAX IA5String
SINGLE-VALUE
)
2.2.2 dSI
DataSet Identifier, a unique identifier for one particular set
of information.
This should be a OID but stored in a stringformat.
( 1.2.752.17.1.21
NAME 'dSI'
EQUALITY caseIgnoreIA5Match
SYNTAX IA5String
)
2.2.3 indexOCAT
Describes the type of data that is stored in this entry, by using
objectcClasses and attributeTypes. The information is stored as
a objectClass name followed by a space and then a attributeType
name.
A typical example when dealing with whitepages information would
be "person cn" .
( 1.2.752.17.1.28
NAME 'indexOCAT'
EQUALITY caseIgnoreIA5Match
SYNTAX IA5String
)
2.2.5 supplierURI
A URI describing which protocols ,hostnames and ports should be used
by a indexserver to interact with servers carrying indexinformation
representing this dataSet.
( 1.2.752.17.1.22
NAME 'supplierURI'
EQUALITY caseIgnoreIA5Match
SYNTAX IA5String
)
2.2.6 baseURI
The attribute value for this attribute is a ldap URI. One can
envisage other URI syntaxes, if the client knows about more access
protocols besides ldap, and the interaction between the client and
the server can not use referrals for some reason.
( 1.2.752.17.1.26
NAME 'baseURI'
EQUALITY caseExactIA5Match
SYNTAX IA5String
)
2.2.7 protocolVersion
Common Indexing Protocol version should be 3 presently.
( 1.2.752.17.1.27
NAME 'protocolVersion'
EQUALITY numericStringMatch
SYNTAX numericString
)
2.2.8 cIPIndexType
What type of index Object that is used to pass around index information.
( 1.2.752.17.1.29
NAME 'cIPIndexType'
EQUALITY caseIgnoreIA5Match
SYNTAX IA5String
)
2.2.10 polledBy
Distinguished Name of Index servers that polls data from this indexserver.
( 1.2.752.17.1.30
NAME 'polledBy'
EQUALITY distinguishedNameMatch
SYNTAX DN
)
2.2.11 updateIntervall
The maximum duration in seconds between the generation of two updates
by the supplier server.
( 1.2.752.17.1.31
Name 'updateIntervall'
EQUALITY numericStringMatch
SYNTAX numericString
SINGLE-VALUE
)
2.2.12 securityOption
Wether and how the supplier server should sign and encrypt the update
before
sending it to the consumer server.
( 1.2.752.17.1.32
NAME 'securityOption'
EQUALITY caseIgnoreIA5Match
SYNTAX IA5String
SINGLE-VALUE
)
2.2.13 extendedDSI
DataSet Identifier possibly followed by a space and a taglist, the later
as
specified by [6].
( 1.2.752.17.1.33
NAME 'extendedDSI'
EQUALITY caseIgnoreIA5Match
SYNTAX IA5String
)
2.2.14 consumerURI
A URI describing be which means a server can accept indexinformation, an
example being a mailto URI for MIME email based index transport.
( 1.2.752.17.1.34
NAME 'consumerURI'
EQUALITY caseExactIA5Match
SYNTAX IA5String
)
2.2.15 attributeNamespace
Any consumer supplier pair has to agree on what attribute that should be
used
and possibly also the meaning of the attributenames. The value of this
attribute
should for example be a URI pointing to a document wherein the agreement is
described.
( 1.2.752.17.1.35
NAME 'attributeNamespace'
EQUALITY caseExactIA5Match
SYNTAX IA5String
)
2.2.16 consistencyBase
This attribute is specificly used by consumer supplier pairs that use the
tagged index object [6].
( 1.2.752.17.1.36
NAME 'consistencyBase'
EQUALITY caseExactIA5Match
SYNTAX IA5String
)
3. The interaction between a client and the Index Mesh
A client interaction with the index mesh consists of a couple
of rather well defined actions. The first being to find a
suitable index to start with, then to transverse the indexmesh and
finally to query the servers holding the original data.
Note when reading this text that what is discussed here is the clients
perception of the DIT, how it is in fact implemented is not discussed.
3.1 Finding a Index Mesh
This approach depends on the fact that every index server partaking
in a Index mesh is represented in the DIT by a entry of the type
cIPDataSet and has a distinguished name (DN) which most
significant relative distinguished name (RDN) has the attributetype
dSI.
Therefore finding a suitable indexserver to start the
search from is a matter of searching the DIT at a suitable
place for objects with the objectClass cIPIndexObject.
Every found entry can then be evaluated by looking at the
description value as well as the indexOCAT value. The description
string should be a human readable and understandable text
that describes what the index server is indexing. An example
of such a string could be "This index covers all employees at Swedish
Universities and University Colleges that has an email account".
The indexOCAT attribute supplies information about which kind
of entries and which attributes within these entries that the
index information has emanated from. If for instance the indexOCAT
attribute value is "person cn" one can deduce that this is
a index over persons and not over for instance roles, and
that it is the attribute commonName that is indexed.
3.2 Searching the mesh
Each index server has its information represented in the DIT
as a very flat tree. In fact it is only one level deep.
0 Indexservers cIPDataSet
/|\
/ | \
/ | \
0 0
cIPDataSet entries cIPIndex entries
one for each DataSet one for each index value
that this server has that this indexserver
gathered indexes from. has.
A search then consists of a set of searches the first being the
search for the index entries that contains a indexvalue that matches
what the user is looking for and the second a search based on the
DSI information in the extendedDSI attribute values returned from
the first search.
In the case of the the cIPIndexType being tagged-index then the
taglists should be compared to find which DSI it might be useful
to pose further queries to.
When doing this type of searches the client should be aware of the fact
that the index values disregarding their origin (attributeTypes) always
are stored in the index server as values of the idx attribute.
The object of the second search is to get information on the different
DataSet involved, and should normally be performed as a read.
Since the DataSet information probably will remain quite stable over time
this information lends itself very well to caching.
If at this stage there are more then one DataSet involved the
User interface might use the description value to aid the user in
choosing which one to proceed with.
The content of the searchBase value of the DataSet tells the client
whether it represents another index server ( the most significant
part of the dn is a dSI attribute ) or if it is a end server.
3.3 Querying the end server
When finally reaching the end server/servers that probably has the
sought for information, the information in the indexOCAT attribute
can be used to produce a appropriate filter.
If a search for "Rol*" in a index having a indexOCAT attribute value
of "person cn" return a idx entry with the idx value of "Roland",
then a appropriate filter to use might be
"&(|(cn=* roland *)(cn=roland *)(cn=* roland))(objectclass=person)".
A complete example of a search process is given in Appendix A.
4 Security considerations
Since this draft deals with client behavior, it does not add anything
that either enhances or diminishes the security features that exists
in LDAP v2.
5. Internationalization
As with security this draft neither enhances or diminishes the handling
of internationalization in LDAP v2.
6. References
[1] W.Yeong, T.Howes and S.Kille, "Lightweight Directory Access Protocol",
RFC 1777
[2] J.Allen and M.Mealling "The Architecture of the Common Indexing
Protocol (CIP)", INTERNET-DRAFT <draft-find-cip-arch-00.txt>,
9 June 1997
[3] The Directory: Overview of Concepts, Models and Service. CCITT
Recommendation X.500, 1988.
[4] Information Processing Systems -- Open Systems Interconnection --
The Directory: Overview of Concepts, Models and Service.
ISO/IEC JTC 1/SC21; International Standard 9594-1, 1988.
[5] M.Wahl, A.Coulbeck, T.Howes and S.Kille,
"Lightweight Directory Access Protocol (v3): Attribute Syntax
Definitions",RFC 2252, december 1997
[6] R.Hedberg, B. Greenblatt, R.Moats and M. Wahl,
"A Tagged Index Object for use in the Common Indexing Protocol",
INTERNET-DRAFT <draft-find-tagged-07.txt>, december 1998
7. Author
Roland Hedberg
Catalogix
Dalsveien 53
0387 Oslo, Norway
Phone: +47 23 08 29 96
EMail: roland@catalogix.ac.se
appendix A - Sample session
Below is a sample of a session between a LDAPv2 client and a index server
mesh as specified in this draft.
The original question of the session is to find the email address of a
person by the name "Roland Hedberg" who is working at "Umea University"
in Sweden.
Step 1.
A singlelevel search with the baseaddress "c=SE" and the filter
"(objectclass=cipDataset)" was issued.
The following results were received:
DN: dSI=1.2.752.17.5.0,c=SE
dsi= 1.2.752.17.5.0
description= "index over employees with emailaddresses within Swedish
higher
education"
indexOCAT= "cn person"
cIPIndexType= "x-tagged-index-1" ;
searchBase= "dsi=1.2.752.17.5.0,c=SE"
protocolVersion = 3
DN: dSI=1.2.752.23.1.3,c=SE
dsi= 1.2.752.23.1.3
description= "index over Swedish lawyers"
indexOCAT= "cn person"
cIPIndexType= "x-tagged-index-1" ;
searchBase= "dsi=1.2.752.23.1.3,c=SE"
protocolVersion = 3
Step 2.
Since the first index seemed to cover the interesting population a singel
level search
with the baseaddress "dsi=1.2.752.17.5.0,c=SE" and the filter
"(|(idx=roland)(idx=hedberg))" was issued.
The following results were received:
DN: idx=Roland,dSI=1.2.752.17.5.0,c=SE
idx= Roland
extendedDSI= 1.2.752.17.5.10 1,473,612,879,1024
extendedDSI= 1.2.752.17.5.14 35,78,150,200
extendedDSI= 1.2.752.17.5.16 187,2031,3167,5284,6034-6040
extendedDSI= 1.2.752.17.5.17 17
DN: idx=Hedberg,dSI=1.2.752.17.5.0,c=SE
idx= Hedberg
extendedDSI= 1.2.752.17.5.8 24,548-552,1066
extendedDSI= 1.2.752.17.5.10 473,512,636,777,1350
extendedDSI= 1.2.752.17.5.14 84,112,143,200
extendedDSI= 1.2.752.17.5.15 1890-1912
extendedDSI= 1.2.752.17.5.17 44
A comparision between the two sets of extendedDSIs shows that two datasets
1.2.752.17.5.10 and 1.2.752.17.5.14 contains persons named "Roland" and
"Hedberg". Therefore the next step would be to see what the datasets
represents.
A comparision like this should normally not be left to the user.
Step. 3
Two baselevel searches, one for
"dsi=1.2.752.17.5.10,dsi=1.2.752.17.5.0,c=SE" and
the other for "dsi=1.2.752.17.5.14,dsi=1.2.752.17.5.0,c=SE" with the filter
"(objectclass=cipdataset)" were issued.
The following results were received:
DN: dSI=1.2.752.17.5.10,dSI=1.2.752.17.5.0,c=SE
dsi= 1.2.752.17.5.10
description= "Employees at Umea University,Sweden"
indexOCAT= "person cn"
searchBase= "o=Umea Universitet,c=SE"
respectively
DN: dSI=1.2.752.17.5.14,dSI=1.2.752.17.5.0,c=SE
dsi= 1.2.752.17.5.14
description= "Employees at Lund University,Sweden"
indexOCAT= "person cn"
searchBase= "o=Lunds Universitet,c=SE"
Step 4
Based on the descriptions for the two datasets, one "1.2.752.17.5.10" was
choosen as the best to proceed with. Since, from the searchbase attribute
value it was clear that this was a base server the query now has to be
somewhat modified.
One possibility would be to issue a query with the baseobject
"o=Umea Universitet,c=SE" and the filter
"(&(cn=Roland Hedberg)(objectclass=person))"