rfc2891.txt

samba最新软件


RFC 2891     LDAP Control Extension for Server Side Sorting  August 2000


   Servers that chain requests to other LDAP servers should ensure that
   the server satisfying the client's request sort the entire result set
   prior to sending back the results.

2.1 Behavior in a chained environment

   If a server receives a sort request, the client expects to receive a
   set of sorted results. If a client submits a sort request to a server
   which chains the request and gets entries from multiple servers, and
   the client has set the criticality of the sort extension to TRUE, the
   server MUST merge sort the results before returning them to the
   client or MUST return unwillingToPerform.

2.2 Other sort issues

   An entry that meets the search criteria may be missing one or more of
   the sort keys. In that case, the entry is considered to have a value
   of NULL for that key. This standard considers NULL to be a larger
   value than all other valid values for that key. For example, if only
   one key is specified, entries which meet the search criteria but do
   not have that key collate after all the entries which do have that
   key. If the reverseOrder flag is set, and only one key is specified,
   entries which meet the search criteria but do not have that key
   collate BEFORE all the entries which do have that key.

   If a sort key is a multi-valued attribute, and an entry happens to
   have multiple values for that attribute and no other controls are
   present that affect the sorting order, then the server SHOULD use the
   least value (according to the ORDERING rule for that attribute).

3.  Interaction with other search controls

   When the sortKeyRequestControl control is included with the
   pagedResultsControl control as specified in [LdapPaged], then the
   server should send the searchResultEntry messages sorted according to
   the sort keys applied to the entire result set. The server should not
   simply sort each page, as this will give erroneous results to the
   client.

   The sortKeyList must be present on each searchRequest message for the
   paged result. It also must not change between searchRequests for the
   same result set. If the server has sorted the data, then it SHOULD
   send back a sortKeyResponseControl control on every searchResultDone
   message for each page. This will allow clients to quickly determine
   if the result set is sorted, rather than waiting to receive the
   entire result set.





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RFC 2891     LDAP Control Extension for Server Side Sorting  August 2000


4.  Security Considerations

   Implementors and administrators should be aware that allowing sorting
   of results could enable the retrieval of a large number of records
   from a given directory service, regardless of administrative limits
   set on the maximum number of records to return.

   A client that desired to pull all records out of a directory service
   could use a combination of sorting and updating of search filters to
   retrieve all records in a database in small result sets, thus
   circumventing administrative limits.

   This behavior can be overcome by the judicious use of permissions on
   the directory entries by the administrator and by intelligent
   implementations of administrative limits on the number of records
   retrieved by a client.

5.  References

   [LDAPv3]    Wahl, M, Kille, S. and T. Howes, "Lightweight Directory
               Access Protocol (v3)", RFC 2251, December 1997.

   [Bradner97] Bradner, S., "Key Words for use in RFCs to Indicate
               Requirement Levels", BCP 14, RFC 2119, March 1997.

   [LdapPaged] Weider, C., Herron, A., Anantha, A. and T. Howes, "LDAP
               Control Extension for Simple Paged Results Manipulation",
               RFC 2696, September 1999.























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RFC 2891     LDAP Control Extension for Server Side Sorting  August 2000


6.  Authors' Addresses

   Anoop Anantha
   Microsoft Corp.
   1 Microsoft Way
   Redmond, WA 98052
   USA

   Phone: [phone]
   EMail: [e-mail]


   Tim Howes
   Loudcloud, Inc.
   615 Tasman Dr.
   Sunnyvale, CA 94089
   USA

   EMail: [e-mail]


   Mark Wahl
   Sun Microsystems, Inc.
   8911 Capital of Texas Hwy Suite 4140
   Austin, TX 78759
   USA

   EMail: [e-mail]























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RFC 2891     LDAP Control Extension for Server Side Sorting  August 2000


7.  Full Copyright Statement

   Copyright (C) The Internet Society (2000).  All Rights Reserved.

   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implementation may be prepared, copied, published
   and distributed, in whole or in part, without restriction of any
   kind, provided that the above copyright notice and this paragraph are
   included on all such copies and derivative works.  However, this
   document itself may not be modified in any way, such as by removing
   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of
   developing Internet standards in which case the procedures for
   copyrights defined in the Internet Standards process must be
   followed, or as required to translate it into languages other than
   English.

   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assigns.

   This document and the information contained herein is provided on an
   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
   BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Acknowledgement

   Funding for the RFC Editor function is currently provided by the
   Internet Society.



















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