The Server Side:
The sortKeyRequestControl specifies one or more attribute types and matching rules for the results returned by a search request. The server SHOULD return all results for the search request in the order specified by the sort keys. If the reverseOrder field is set to TRUE, then the entries will be presented in reverse sorted order for the specified key.
There are six possible scenarios that may occur as a result of the sort control being included on the search request:
1 - If the server does not support this sorting control and the
client specified TRUE for the control's criticality field, then
the server MUST return unavailableCriticalExtension as a return
code in the searchResultDone message and not send back any other
results. This behavior is specified in section 4.1.12 of
[LDAPv3].
2 - If the server does not support this sorting control and the
client specified FALSE for the control's criticality field, then
the server MUST ignore the sort control and process the search
request as if it were not present. This behavior is specified in
section 4.1.12 of [LDAPv3].
3 - If the server supports this sorting control but for some reason
cannot sort the search results using the specified sort keys and
the client specified TRUE for the control's criticality field,
then the server SHOULD do the following: return
unavailableCriticalExtension as a return code in the
searchResultDone message; include the sortKeyResponseControl in
the searchResultDone message, and not send back any search result
entries.
4 - If the server supports this sorting control but for some reason
cannot sort the search results using the specified sort keys and
the client specified FALSE for the control's criticality field,
then the server should return all search results unsorted and
include the sortKeyResponseControl in the searchResultDone
message.
5 - If the server supports this sorting control and can sort the
search results using the specified sort keys, then it should
include the sortKeyResponseControl in the searchResultDone
message with a sortResult of success.
6 - If the search request failed for any reason and/or there are no
searchResultEntry messages returned for the search response, then
the server SHOULD omit the sortKeyResponseControl from the
searchResultDone message.
The Client Side:
1- The client application is assured that the results are sorted in the
specified key order if and only if the result code in the
sortKeyResponseControl is success. If the server omits the
sortKeyResponseControl from the searchResultDone message, the client
SHOULD assume that the sort control was ignored by the server.
2- The sortKeyResponseControl, if included by the server in the
searchResultDone message, should have the sortResult set to either
success if the results were sorted in accordance with the keys
specified in the sortKeyRequestControl or set to the appropriate
error code as to why it could not sort the data (such as
noSuchAttribute or inappropriateMatching). Optionally, the server MAY
set the attributeType to the first attribute type specified in the
SortKeyList that was in error. The client SHOULD ignore the
attributeType field if the sortResult is success.
3- The server may not be able to sort the results using the specified
sort keys because it may not recognize one of the attribute types,
the matching rule associated with an attribute type is not
applicable, or none of the attributes in the search response are of
these types. Servers may also restrict the number of keys allowed in
the control, such as only supporting a single key.
