FIND Working Group                                   Roland Hedberg
Internet-Draft                                      Umea University
Expires in six month                               November 3, 1997

                   LDAPv2 client Vs the Index Mesh

Status of this Memo

   This document is an Internet-Draft.  Internet-Drafts are working
   documents of the Internet Engineering Task Force (IETF), its
   areas, and its working groups.  Note that other groups may also
   distribute working documents as Internet-Drafts.

   Internet-Drafts are draft documents valid for a maximum of six
   months and may be updated, replaced, or obsoleted by other
   documents at any time.  It is inappropriate to use Internet-
   Drafts as reference material or to cite them other than as
   ``work in progress.''

   To learn the current status of any Internet-Draft, please check
   the ``1id-abstracts.txt'' listing contained in the Internet-
   Drafts Shadow Directories on (Africa), (Europe), (US West Coast), (US East Coast), or (Pacific Rim).

   Distribution of this memo is unlimited.  Editorial comments should
   be sent to the author (  Technical
   discussion will take place on the IETF FIND mailing list


   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'
     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'
     MUST ( dSI $ searchBase )
     MAY ( indexOCAT $ description $ cIPIndexType $
           accessPoint $ protocolVersion $ polledBy $
           updateIntervall $ securityOption

2.2 The CIP attributeTypes

   The attributes idx, indexOCAT, extendedDSI, description,
   cIPIndexType, searchBase, dSI are used by a client acessing the
   index server.
   The other attributes ( accesspoint, protocolVersion, polledBy,
   updateIntervall and securityOption) 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

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
   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 searchBase

   The attribute value for this attribute can be expressed in one of
   two formats, either a distinguished name or 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 'searchBase'
     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

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

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

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

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
   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 it's 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 would be
   "&(|(cn=* roland *)(cn=roland *)(cn=* roland))(objectclass=person)".

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", INTERNET-DRAFT <draft-ietf-asid-ldapv3-attributes-06.txt>
   11 July 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-03.txt>, 1997

7. Author

   Roland Hedberg
   Umea University
   S-901 87 Umea, Sweden

   Phone: +46 90 7865165
   Fax:   +46 90 7866766