- INTERNET-DRAFT D. Boreham, Bozeman Pass
- LDAPext Working Group J. Sermersheim, Novell
- Category: Standards Track A. Anantha, Microsoft
- <draft-ietf-ldapext-ldapv3-vlv-05.txt> M. Armijo, Microsoft
- Expires: May 2002 A. Kashi, Microsoft
- November 2001
+Internet-Draft D. Boreham, Bozeman Pass
+LDAPext Working Group J. Sermersheim, Novell
+Intended Category: Standards Track A. Kashi, Microsoft
+<draft-ietf-ldapext-ldapv3-vlv-06.txt>
+Expires: Nov 2002 May 2002
-
- LDAP Extensions for Scrolling View Browsing of Search Results
-
+ LDAP Extensions for Scrolling View Browsing of Search Results
1. Status of this Memo
all provisions of Section 10 of RFC2026.
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.
+ 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."
+ 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."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
- This document is intended to be submitted, after review and
- revision, as a Standards Track document. Distribution of this memo
- is unlimited. It is filed as <draft-ietf-ldapext-ldapv3-vlv-
- 05.txt>, and expires May, 2002.
-
+ This document is intended to be submitted, after review and revision,
+ as a Standards Track document. Distribution of this memo is
+ unlimited.
Please send comments to the authors.
2. Abstract
- This document describes a Virtual List View control extension for
- the Lightweight Directory Access Protocol (LDAP) Search operation.
- This control is designed to allow the "virtual list box" feature,
- common in existing commercial e-mail address book applications, to
- be supported efficiently by LDAP servers. LDAP servers' inability to
+ This document describes a Virtual List View control extension for the
+ Lightweight Directory Access Protocol (LDAP) Search operation. This
+ control is designed to allow the "virtual list box" feature, common
+ in existing commercial e-mail address book applications, to be
+ supported efficiently by LDAP servers. LDAP servers' inability to
support this client feature is a significant impediment to LDAP
replacing proprietary protocols in commercial e-mail systems.
-
- Boreham et al Standards Track 1 \f
- LDAP Extensions for Scrolling View November 2001
- Browsing of Search Results
-
The control allows a client to specify that the server return, for a
given LDAP search with associated sort keys, a contiguous subset of
the search result set. This subset is specified in terms of offsets
into the ordered list, or in terms of a greater than or equal
comparison value.
+
+ Boreham et al Internet-Draft 1
+\f
+ LDAP Extensions for Scrolling View May 2002
+ Browsing of Search Results
+
3. Conventions used in this document
- The key words ``MUST'', ``MUST NOT'', ``REQUIRED'', ``SHALL'',
- ``SHALL NOT'', ``SHOULD'', ``SHOULD NOT'', ``RECOMMENDED'', and
- ``MAY'' in this document are to be interpreted as described in RFC
- 2119 [Bradner97].
+ The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
+ "SHOULD", "SHOULD NOT", "RECOMMENDED", and "MAY" in this document are
+ to be interpreted as described in RFC 2119 [Bradner97].
4. Background
- A Virtual List is a graphical user interface technique employed
- where ordered lists containing a large number of entries need to be
- displayed. A window containing a small number of visible list
- entries is drawn. The visible portion of the list may be relocated
- to different points within the list by means of user input. This
- input can be to a scroll bar slider; from cursor keys; from page
- up/down keys; from alphanumeric keys for "typedown". The user is
- given the impression that they may browse the complete list at will,
- even though it may contain millions of entries. It is the fact that
- the complete list contents are never required at any one time that
- characterizes Virtual List View. Rather than fetch the complete
- list from wherever it is stored (typically from disk or a remote
- server), only that information which is required to display the part
- of the list currently in view is fetched. The subject of this
- document is the interaction between client and server required to
- implement this functionality in the context of the results from a
- sorted LDAP search request.
+ A Virtual List is a graphical user interface technique employed where
+ ordered lists containing a large number of entries need to be
+ displayed. A window containing a small number of visible list entries
+ is drawn. The visible portion of the list may be relocated to
+ different points within the list by means of user input. This input
+ can be to a scroll bar slider; from cursor keys; from page up/down
+ keys; from alphanumeric keys for "typedown". The user is given the
+ impression that they may browse the complete list at will, even
+ though it may contain millions of entries. It is the fact that the
+ complete list contents are never required at any one time that
+ characterizes Virtual List View. Rather than fetch the complete list
+ from wherever it is stored (typically from disk or a remote server),
+ only that information which is required to display the part of the
+ list currently in view is fetched. The subject of this document is
+ the interaction between client and server required to implement this
+ functionality in the context of the results from a sorted LDAP search
+ request.
For example, suppose an e-mail address book application displays a
- list view onto the list containing the names of all the holders of
- e-mail accounts at a large university. The list is sorted
- alphabetically. While there may be tens of thousands of entries in
+ list view onto the list containing the names of all the holders of e-
+ mail accounts at a large university. The list is sorted
+ alphabetically. While there may be tens of thousands of entries in
this list, the address book list view displays only 20 such accounts
- at any one time. The list has an accompanying scroll bar and text
- input window for type-down. When first displayed, the list view
- shows the first 20 entries in the list, and the scroll bar slider is
- positioned at the top of its range. Should the user drag the slider
+ at any one time. The list has an accompanying scroll bar and text
+ input window for type-down. When first displayed, the list view shows
+ the first 20 entries in the list, and the scroll bar slider is
+ positioned at the top of its range. Should the user drag the slider
to the bottom of its range, the displayed contents of the list view
- should be updated to show the last 20 entries in the list.
- Similarly, if the slider is positioned somewhere in the middle of
- its travel, the displayed contents of the list view should be
- updated to contain the 20 entries located at that relative position
- within the complete list. Starting from any display point, if the
- user uses the cursor keys or clicks on the scroll bar to request
- that the list be scrolled up or down by one entry, the displayed
- contents should be updated to reflect this. Similarly the list
- should be displayed correctly when the user requests a page scroll
-
- Boreham et al Standards Track 2 \f
- LDAP Extensions for Scrolling View November 2001
+ should be updated to show the last 20 entries in the list. Similarly,
+ if the slider is positioned somewhere in the middle of its travel,
+ the displayed contents of the list view should be updated to contain
+ the 20 entries located at that relative position within the complete
+ list. Starting from any display point, if the user uses the cursor
+ keys or clicks on the scroll bar to request that the list be scrolled
+ up or down by one entry, the displayed contents should be updated to
+ reflect this. Similarly the list should be displayed correctly when
+ the user requests a page scroll up or down. Finally, when the user
+ types characters in the type-down window, the displayed contents of
+ the list should "jump" or "seek" to the appropriate point within the
+ list. For example, if the user types "B", the displayed list could
+ center around the first user with a name beginning with the letter
+ "B". When this happens, the scroll bar slider should also be updated
+ to reflect the new relative location within the list.
+
+ Boreham et al Internet-Draft 2
+\f
+ LDAP Extensions for Scrolling View May 2002
Browsing of Search Results
- up or down. Finally, when the user types characters in the type-
- down window, the displayed contents of the list should "jump" or
- "seek" to the appropriate point within the list. For example, if
- the user types "B", the displayed list could center around the first
- user with a name beginning with the letter "B". When this happens,
- the scroll bar slider should also be updated to reflect the new
- relative location within the list.
- This document defines a request control which extends the LDAP
- search operation. Always used in conjunction with the server side
- sorting control [SSS], this allows a client to retrieve selected
- portions of large search result set in a fashion suitable for the
- implementation of a virtual list view.
+ This document defines a request control which extends the LDAP search
+ operation. Always used in conjunction with the server side sorting
+ control [SSS], this allows a client to retrieve selected portions of
+ large search result set in a fashion suitable for the implementation
+ of a virtual list view.
5. Client-Server Interaction
- The Virtual List View control extends a regular LDAP Search
- operation which must also include a server-side sorting control
- [SSS]. Rather than returning the complete set of appropriate
- SearchResultEntry messages, the server is instructed to return a
- contiguous subset of those entries, taken from the sorted result
- set, centered around a particular target entry. Henceforth, in the
- interests of brevity, the sorted search result set will be referred
- to as "the list".
+ The Virtual List View control extends a regular LDAP Search operation
+ which must also include a server-side sorting control [SSS]. Rather
+ than returning the complete set of appropriate SearchResultEntry
+ messages, the server is instructed to return a contiguous subset of
+ those entries, taken from the sorted result set, centered around a
+ particular target entry. Henceforth, in the interests of brevity, the
+ sorted search result set will be referred to as "the list".
The sort control MAY contain any sort specification valid for the
- server. The attributeType field in the first SortKeyList sequence
+ server. The attributeType field in the first SortKeyList sequence
element has special significance for "typedown".
The desired target entry and the number of entries to be returned,
both before and after that target entry in the list, are determined
by the client's VirtualListViewRequest control.
- When the server returns the set of entries to the client, it
- attaches a VirtualListViewResponse control to the SearchResultDone
- message. The server returns in this control: its current estimate
- for the list content count, the location within the list
- corresponding to the target entry, and any error codes.
+ When the server returns the set of entries to the client, it attaches
+ a VirtualListViewResponse control to the SearchResultDone message.
+ The server returns in this control: its current estimate for the list
+ content count, the location within the list corresponding to the
+ target entry, any error codes, and optionally a context identifier.
The target entry is specified in the VirtualListViewRequest control
- by one of two methods. The first method is for the client to
- indicate the target entry's offset within the list. The second way
- is for the client to supply an attribute assertion value. The value
- is compared against the values of the attribute specified as the
- primary sort key in the sort control attached to the search
- operation. The first sort key in the SortKeyList is the primary
- sort key. The target entry is the first entry in the list with
- value greater than or equal to (in the primary sort order), the
- presented value. The order is determined by rules defined in [SSS].
- Selection of the target entry by this means is designed to implement
- "typedown". Note that it is possible that no entry satisfies these
-
- Boreham et al Standards Track 3 \f
- LDAP Extensions for Scrolling View November 2001
+ by one of two methods. The first method is for the client to indicate
+ the target entry's offset within the list. The second way is for the
+ client to supply an attribute assertion value. The value is compared
+ against the values of the attribute specified as the primary sort key
+ in the sort control attached to the search operation. The first sort
+ key in the SortKeyList is the primary sort key. The target entry is
+ the first entry in the list with value greater than or equal to (in
+ the primary sort order), the presented value. The order is determined
+ by rules defined in [SSS]. Selection of the target entry by this
+ means is designed to implement "typedown". Note that it is possible
+ that no entry satisfies these conditions, in which case there is no
+ target entry. This condition is indicated by the server returning the
+ special value contentCount + 1 in the target position field.
+
+ Because the server may not have an accurate estimate of the number of
+ entries in the list, and to take account of cases where the list size
+ is changing during the time the user browses the list, and because
+ the client needs a way to indicate specific list targets "beginning"
+
+ Boreham et al Internet-Draft 3
+\f
+ LDAP Extensions for Scrolling View May 2002
Browsing of Search Results
- conditions, in which case there is no target entry. This condition
- is indicated by the server returning the special value contentCount
- + 1 in the target position field.
-
- Because the server may not have an accurate estimate of the number
- of entries in the list, and to take account of cases where the list
- size is changing during the time the user browses the list, and
- because the client needs a way to indicate specific list
- targets "beginning" and "end", offsets within the list are
- transmitted between client and server as ratios---offset to
- content count. The server sends its latest estimate as to the number
- of entries in the list (content count) to the client in every
- response control. The client sends its assumed value for the
- content count in every request control. The server examines the
- content count and offsets presented by the client and computes the
- corresponding offsets within the list, based on its own idea of the
- content count.
+ and "end", offsets within the list are transmitted between client and
+ server as ratios---offset to content count. The server sends its
+ latest estimate as to the number of entries in the list (content
+ count) to the client in every response control. The client sends its
+ assumed value for the content count in every request control. The
+ server examines the content count and offsets presented by the client
+ and computes the corresponding offsets within the list, based on its
+ own idea of the content count.
Si = Sc * (Ci / Cc)
the content count most recently received, Cc = Sc and the offsets
transmitted become the actual server list offsets.
- The following special cases are allowed: a client sending a
- content count of zero (Cc = 0) means "client has no idea what the
- content count is, server MUST use its own content count estimate
- in place of the client's". An offset value of one (Ci = 1)
- always means that the target is the first entry in the list. Client
- specifying an offset which equals the content count specified in the
- same request control (Ci = Cc) means that the target is the last
- entry in the list. Ci may only equal zero when Cc is also zero.
- This signifies the last entry in the list.
+ The following special cases exist when the client is specifying the
+ offset and content count:
+ - an offset of one and a content count of non-one (Ci = 1, Cc != 1)
+ indicates that the target is the first entry in the list.
+ - equivalent values (Ci = Cc) indicate that the target is the last
+ entry in the list.
+ - a content count of zero, and a non-zero offset (Cc = 0, Ci != 0)
+ means the client has no idea what the content count is, the server
+ MUST use its own content count estimate in place of the client's.
Because the server always returns contentCount and targetPosition,
the client can always determine which of the returned entries is the
- target entry. Where the number of entries returned is the same as
- the number requested, the client is able to identify the target by
- simple arithmetic. Where the number of entries returned is not the
- same as the number requested (because the requested range crosses
- the beginning or end of the list, or both), the client must use the
+ target entry. Where the number of entries returned is the same as the
+ number requested, the client is able to identify the target by simple
+ arithmetic. Where the number of entries returned is not the same as
+ the number requested (because the requested range crosses the
+ beginning or end of the list, or both), the client must use the
target position and content count values returned by the server to
- identify the target entry. For example, suppose that 10 entries
- before and 10 after the target were requested, but the server
- returns 13 entries, a content count of 100 and a target position of
+ identify the target entry. For example, suppose that 10 entries
+ before and 10 after the target were requested, but the server returns
+ 13 entries, a content count of 100 and a target position of 3. The
+ client can determine that the first entry must be entry number 1 in
+ the list, therefore the 13 entries returned are the first 13 entries
+ in the list, and the target is the third one.
+
+ A server-generated context identifier MAY be returned to clients. A
+ client receiving a context identifier SHOULD return it unchanged in a
+ subsequent request which relates to the same list. The purpose of
+
- Boreham et al Standards Track 4 \f
- LDAP Extensions for Scrolling View November 2001
+ Boreham et al Internet-Draft 4
+\f
+ LDAP Extensions for Scrolling View May 2002
Browsing of Search Results
- 3. The client can determine that the first entry must be entry
- number 1 in the list, therefore the 13 entries returned are the
- first 13 entries in the list, and the target is the third one.
-
- A server-generated context identifier MAY be returned to clients. A
- client receiving a context identifier SHOULD return it unchanged in
- a subsequent request which relates to the same list. The purpose of
this interaction is to enhance the performance and effectiveness of
servers which employ approximate positioning.
This control is included in the SearchRequest message as part of the
controls field of the LDAPMessage, as defined in Section 4.1.12 of
- [LDAPv3]. The controlType is set to "2.16.840.1.113730.3.4.9". The
- criticality SHOULD be set to TRUE. If this control is included in a
+ [LDAPv3]. The controlType is set to "2.16.840.1.113730.3.4.9". The
+ criticality SHOULD be set to TRUE. If this control is included in a
SearchRequest message, a Server Side Sorting request control [SSS]
MUST also be present in the message. The controlValue is an OCTET
STRING whose value is the BER-encoding of the following SEQUENCE:
- VirtualListViewRequest ::= SEQUENCE {
- beforeCount INTEGER (0..maxInt),
- afterCount INTEGER (0..maxInt),
- CHOICE {
- byoffset [0] SEQUENCE {
- offset INTEGER (0 .. maxInt),
- contentCount INTEGER (0 .. maxInt) },
- greaterThanOrEqual [1] AssertionValue },
- contextID OCTET STRING OPTIONAL }
+ VirtualListViewRequest ::= SEQUENCE {
+ beforeCount INTEGER (0..maxInt),
+ afterCount INTEGER (0..maxInt),
+ CHOICE {
+ byoffset [0] SEQUENCE {
+ offset INTEGER (0 .. maxInt),
+ contentCount INTEGER (0 .. maxInt) },
+ greaterThanOrEqual [1] AssertionValue },
+ contextID OCTET STRING OPTIONAL }
beforeCount indicates how many entries before the target entry the
- client wants the server to send. afterCount indicates the number of
- entries after the target entry the client wants the server to send.
+ client wants the server to send. afterCount indicates the number of
+ entries after the target entry the client wants the server to send.
offset and contentCount identify the target entry as detailed in
- section 4. greaterThanOrEqual is an attribute assertion value
- defined in [LDAPv3]. If present, the value supplied in
- greaterThanOrEqual is used to determine the target entry by
- comparison with the values of the attribute specified as the primary
- sort key. The first list entry who's value is no less than (less
- than or equal to when the sort order is reversed) the supplied value
- is the target entry. If present, the contextID field contains the
- value of the most recently received contextID field from a
- VirtualListViewResponse control. The type AssertionValue and value
- maxInt are defined in [LDAPv3]. contextID values have no validity
- outwith the connection on which they were received. That is, a
-
- Boreham et al Standards Track 5 \f
- LDAP Extensions for Scrolling View November 2001
- Browsing of Search Results
-
- client should not submit a contextID which it received from another
- connection, a connection now closed, or a different server.
+ section 4. greaterThanOrEqual is an attribute assertion value defined
+ in [LDAPv3]. If present, the value supplied in greaterThanOrEqual is
+ used to determine the target entry by comparison with the values of
+ the attribute specified as the primary sort key. The first list entry
+ who's value is no less than (less than or equal to when the sort
+ order is reversed) the supplied value is the target entry. If
+ present, the contextID field contains the value of the most recently
+ received contextID field from a VirtualListViewResponse control. The
+ type AssertionValue and value maxInt are defined in [LDAPv3].
+ contextID values have no validity outwith the connection on which
+ they were received. That is, a client should not submit a contextID
+ which it received from another connection, a connection now closed,
+ or a different server.
6.2. Response Control
+
+ Boreham et al Internet-Draft 5
+\f
+ LDAP Extensions for Scrolling View May 2002
+ Browsing of Search Results
+
This control is included in the SearchResultDone message as part of
the controls field of the LDAPMessage, as defined in Section 4.1.12
of [LDAPv3].
- The controlType is set to "2.16.840.1.113730.3.4.10". The
- criticality is FALSE (MAY be absent). The controlValue is an OCTET
- STRING, whose value is the BER encoding of a value of the following
- SEQUENCE:
-
- VirtualListViewResponse ::= SEQUENCE {
- targetPosition INTEGER (0 .. maxInt),
- contentCount INTEGER (0 .. maxInt),
- virtualListViewResult ENUMERATED {
- success (0),
- operationsError (1),
- unwillingToPerform (53),
- insufficientAccessRights (50),
- busy (51),
- timeLimitExceeded (3),
- adminLimitExceeded (11),
- sortControlMissing (60),
- offsetRangeError (61),
- other (80) },
- contextID OCTET STRING OPTIONAL }
-
- targetPosition gives the list offset for the target entry.
+ The controlType is set to "2.16.840.1.113730.3.4.10". The criticality
+ is FALSE (MAY be absent). The controlValue is an OCTET STRING, whose
+ value is the BER encoding of a value of the following SEQUENCE:
+
+ VirtualListViewResponse ::= SEQUENCE {
+ targetPosition INTEGER (0 .. maxInt),
+ contentCount INTEGER (0 .. maxInt),
+ virtualListViewResult ENUMERATED {
+ success (0),
+ operationsError (1),
+ unwillingToPerform (53),
+ insufficientAccessRights (50),
+ busy (51),
+ timeLimitExceeded (3),
+ adminLimitExceeded (11),
+ sortControlMissing (60),
+ offsetRangeError (61),
+ other (80) },
+ contextID OCTET STRING OPTIONAL }
+
+ targetPosition gives the list offset for the target entry.
contentCount gives the server's estimate of the current number of
- entries in the list. Together these give sufficient information for
+ entries in the list. Together these give sufficient information for
the client to update a list box slider position to match the newly
retrieved entries and identify the target entry. The contentCount
value returned SHOULD be used in a subsequent VirtualListViewRequest
- control. contextID is a server-defined octet string. If present,
- the contents of the contextID field SHOULD be returned to the server
- by a client in a subsequent VirtualListViewRequest control.
+ control. contextID is a server-defined octet string. If present, the
+ contents of the contextID field SHOULD be returned to the server by a
+ client in a subsequent VirtualListViewRequest control.
- The virtualListViewResult codes which are common to the LDAP
+ The virtualListViewResult codes which are common to the LDAP
searchResponse (adminLimitExceeded, timeLimitExceeded, busy,
operationsError, unwillingToPerform, insufficientAccessRights) have
the same meanings as defined in [LDAPv3], but they pertain
- specifically to the VLV operation. For example, the server could
+ specifically to the VLV operation. For example, the server could
exceed an administration limit processing a SearchRequest with a
VirtualListViewRequest control. However, the same administration
limit would not be exceeded should the same SearchRequest be
- submitted by the client without the VirtualListViewRequest control.
+ submitted by the client without the VirtualListViewRequest control.
In this case, the client can determine that an administration limit
- has been exceeded in servicing the VLV request, and can if it
-
- Boreham et al Standards Track 6 \f
- LDAP Extensions for Scrolling View November 2001
- Browsing of Search Results
-
- chooses resubmit the SearchRequest without the
- VirtualListViewRequest control.
+ has been exceeded in servicing the VLV request, and can if it chooses
+ resubmit the SearchRequest without the VirtualListViewRequest
+ control.
insufficientAccessRights means that the server denied the client
permission to perform the VLV operation.
+
+ Boreham et al Internet-Draft 6
+\f
+ LDAP Extensions for Scrolling View May 2002
+ Browsing of Search Results
+
If the server determines that the results of the search presented
- exceed the range provided by the 32-bit offset values, it MUST
- return offsetRangeError.
+ exceed the range specified in INTEGER values, it MUST return
+ offsetRangeError.
+
+6.2.1 virtualListViewError
+
+ A new LDAP error is introduced called virtualListViewError. Its value
+ is 76.
+ [Note to the IESG/IANA/RFC Editor: the value 76 has been suggested by
+ experts, had expert review, and is currently being used by some
+ implementations. The intent is to have this number designated as an
+ official IANA assigned LDAP Result Code (see draft-ietf-ldapbis-iana-
+ xx.txt, Section 3.5)]
- If the server returns any code other then success (0) for
- virtualListViewResult, then the server MUST return controlError (76)
- as the resultCode of the SearchResultDone message. [ctrlErr]
+ If the server returns any code other than success (0) for
+ virtualListViewResult, then the server SHOULD return
+ virtualListViewError as the resultCode of the SearchResultDone
+ message.
7. Protocol Example
Here we walk through the client-server interaction for a specific
- virtual list view example: The task is to display a list of all
- 78564 people in the US company "Ace Industry". This will be done by
+ virtual list view example: The task is to display a list of all 78564
+ people in the US company "Ace Industry". This will be done by
creating a graphical user interface object to display the list
contents, and by repeatedly sending different versions of the same
virtual list view search request to the server. The list view
We form a search with baseDN "o=Ace Industry, c=us"; search scope
subtree; filter "objectClass=inetOrgPerson". We attach a server sort
order control to the search, specifying ascending sort on attribute
- "cn". To this base search, we attach a virtual list view request
+ "cn". To this base search, we attach a virtual list view request
control with contents determined by the user activity and send the
- search to the server. We display the results from each search in
- the list window and update the slider position.
+ search to the server. We display the results from each search in the
+ list window and update the slider position.
When the list view is first displayed, we want to initialize the
contents showing the beginning of the list. Therefore, we set
beforeCount = 0, afterCount = 19, contentCount = 0, offset = 1 and
- send the request to the server. The server duly returns the first
- 20 entries in the list, plus the content count = 78564 and
- targetPosition = 1. We therefore leave the scroll bar slider at its
+ send the request to the server. The server duly returns the first 20
+ entries in the list, plus the content count = 78564 and
+ targetPosition = 1. We therefore leave the scroll bar slider at its
current location (the top of its range).
- Say that next the user drags the scroll bar slider down to the
- bottom of its range. We now wish to display the last 20 entries in
- the list, so we set beforeCount = 19, afterCount = 0, contentCount =
- 78564, offset = 78564 and send the request to the server. The server
- returns the last 20 entries in the list, plus the content count =
- 78564 and targetPosition = 78564.
-
- Next the user presses a page up key. Our page size is 20, so we
- set beforeCount = 0, afterCount = 19, contentCount = 78564,
- offset = 78564-19-20 and send the request to the server. The server
+ Say that next the user drags the scroll bar slider down to the bottom
+ of its range. We now wish to display the last 20 entries in the list,
+ so we set beforeCount = 19, afterCount = 0, contentCount = 78564,
+ offset = 78564 and send the request to the server. The server returns
+
- Boreham et al Standards Track 7 \f
- LDAP Extensions for Scrolling View November 2001
+ Boreham et al Internet-Draft 7
+\f
+ LDAP Extensions for Scrolling View May 2002
Browsing of Search Results
- returns the preceding 20 entries in the list, plus the content count
- = 78564 and targetPosition = 78525.
+ the last 20 entries in the list, plus the content count = 78564 and
+ targetPosition = 78564.
+
+ Next the user presses a page up key. Our page size is 20, so we set
+ beforeCount = 0, afterCount = 19, contentCount = 78564, offset =
+ 78564-19-20 and send the request to the server. The server returns
+ the preceding 20 entries in the list, plus the content count = 78564
+ and targetPosition = 78525.
Now the user grabs the scroll bar slider and drags it to 68% of the
- way down its travel. 68% of 78564 is 53424 so we set beforeCount =
- 9, afterCount = 10, contentCount = 78564, offset = 53424 and send
- the request to the server. The server returns the preceding 20
- entries in the list, plus the content count = 78564 and
- targetPosition = 53424.
+ way down its travel. 68% of 78564 is 53424 so we set beforeCount = 9,
+ afterCount = 10, contentCount = 78564, offset = 53424 and send the
+ request to the server. The server returns the preceding 20 entries in
+ the list, plus the content count = 78564 and targetPosition = 53424.
Lastly, the user types the letter "B". We set beforeCount = 9,
afterCount = 10 and greaterThanOrEqual = "B". The server finds the
first entry in the list not less than "B", let's say "Babs Jensen",
and returns the nine preceding entries, the target entry, and the
- proceeding 10 entries. The server returns content count = 78564 and
- targetPosition = 5234 and so the client updates its scroll bar
- slider to 6.7% of full scale.
+ proceeding 10 entries. The server returns content count = 78564 and
+ targetPosition = 5234 and so the client updates its scroll bar slider
+ to 6.7% of full scale.
8. Notes for Implementers
While the feature is expected to be generally useful for arbitrary
- search and sort specifications, it is specifically designed for
- those cases where the result set is very large. The intention is
- that this feature be implemented efficiently by means of pre-
- computed indices pertaining to a set of specific cases. For
- example, an offset relating to "all the employees in the local
- organization, sorted by surname" would be a common case.
+ search and sort specifications, it is specifically designed for those
+ cases where the result set is very large. The intention is that this
+ feature be implemented efficiently by means of pre-computed indices
+ pertaining to a set of specific cases. For example, an offset
+ relating to "all the employees in the local organization, sorted by
+ surname" would be a common case.
The intention for client software is that the feature should fit
easily with the host platform's graphical user interface facilities
information received from the list view code to match the format of
the virtual list view request and response controls.
- Client implementers should note that any offset value returned by
- the server may be approximate. Do not design clients > which only
- operate correctly when offsets are exact.
+ Client implementers should note that any offset value returned by the
+ server may be approximate. Do not design clients > which only operate
+ correctly when offsets are exact.
Server implementers using indexing technology which features
- approximate positioning should consider returning context
- identifiers to clients. The use of a context identifier will allow
- the server to distinguish between client requests which relate to
- different displayed lists on the client. Consequently the server can
- decide more intelligently whether to reposition an existing database
- cursor accurately to within a short distance of its current
- position, or to reposition to an approximate position. Thus the
- client will see precise offsets for "short" repositioning (e.g.
- paging up or down), but approximate offsets for a "long" reposition
- (e.g. a slider movement).
-
-
- Boreham et al Standards Track 8 \f
- LDAP Extensions for Scrolling View November 2001
+ approximate positioning should consider returning context identifiers
+ to clients. The use of a context identifier will allow the server to
+ distinguish between client requests which relate to different
+ displayed lists on the client. Consequently the server can decide
+ more intelligently whether to reposition an existing database cursor
+
+ Boreham et al Internet-Draft 8
+\f
+ LDAP Extensions for Scrolling View May 2002
Browsing of Search Results
- Server implementers are free to return status code
- unwillingToPerform should their server be unable to service any
- particular VLV search. This might be because the resolution of the
- search is computationally infeasible, or because excessive server
- resources would be required to service the search.
+ accurately to within a short distance of its current position, or to
+ reposition to an approximate position. Thus the client will see
+ precise offsets for "short" repositioning (e.g. paging up or down),
+ but approximate offsets for a "long" reposition (e.g. a slider
+ movement).
+
+ Server implementers are free to return status code unwillingToPerform
+ should their server be unable to service any particular VLV search.
+ This might be because the resolution of the search is computationally
+ infeasible, or because excessive server resources would be required
+ to service the search.
Client implementers should note that this control is only defined on
a client interaction with a single server. If a server returns
- referrals as a part of its response to the search request, the
- client is responsible for deciding when and how to apply this
- control to the referred-to servers, and how to collate the results
- from multiple servers.
+ referrals as a part of its response to the search request, the client
+ is responsible for deciding when and how to apply this control to the
+ referred-to servers, and how to collate the results from multiple
+ servers.
9. Relationship to "Simple Paged Results"
[SPaged]. However, the controls described here support any operation
possible with the Simple Paged Results mechanism. The two mechanisms
are not complementary; rather one has a superset of the other's
- features. One area where the mechanism presented here is not a
- strict superset of the Simple Paged Results scheme is that here we
- require a sort order to be specified. No such requirement is made
- for paged results.
+ features. One area where the mechanism presented here is not a strict
+ superset of the Simple Paged Results scheme is that here we require a
+ sort order to be specified. No such requirement is made for paged
+ results.
10. Security Considerations
undesirable in some circumstances and consequently it may be
necessary to enforce some access control.
- Clients can, using this control, determine how many entries are
- contained within a portion of the DIT. This may constitute a
- security hazard. Again, access controls may be appropriate.
+
+
- Server implementers SHOULD exercise caution concerning the content
- of the contextID. Should the contextID contain internal server
- state, it may be possible for a malicious client to use that
- information to gain unauthorized access to information.
+ Boreham et al Internet-Draft 9
+\f
+ LDAP Extensions for Scrolling View May 2002
+ Browsing of Search Results
+ Clients can, using this control, determine how many entries are
+ contained within a portion of the DIT. This may constitute a security
+ hazard. Again, access controls may be appropriate.
- Boreham et al Standards Track 9 \f
- LDAP Extensions for Scrolling View November 2001
- Browsing of Search Results
+ Server implementers SHOULD exercise caution concerning the content of
+ the contextID. Should the contextID contain internal server state, it
+ may be possible for a malicious client to use that information to
+ gain unauthorized access to information.
11. Acknowledgements
- Chris Weider of Microsoft co-authored a previous version of this
- document.
+ Chris Weider, Anoop Anantha, and Michael Armijo of Microsoft co-
+ authored previous versions of this document.
12. References
December, 1997.
[SPaged] Weider, C., Herron, A., Anantha, A. and T. Howes, "LDAP
- Control Extension for Simple Paged Results
- Manipulation", RFC2696, September 1999.
+ Control Extension for Simple Paged Results Manipulation",
+ RFC2696, September 1999.
[SSS] Wahl, M., Herron, A. and T. Howes, "LDAP Control
Extension for Server Side Sorting of Search Results",
[Bradner97] Bradner, S., "Key Words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
+
- [ctrlErr] Armijo, M. and A. Kashi, ôResult Code for LDAP
- Controlsö, Internet-Draft, September, 2001.
- Work in progress published as:
- <draft-armijo-ldap-control-error-02.txt>
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ Boreham et al Internet-Draft 10
+\f
+ LDAP Extensions for Scrolling View May 2002
+ Browsing of Search Results
13. Authors' Addresses
david@bozemanpass.com
Jim Sermersheim
- Novell
- 122 East 1700 South
+ Novell, Inc
+ 1800 South Novell Place
Provo, Utah 84606, USA
jimse@novell.com
- Anoop Anantha
- Microsoft Corporation
- 1 Microsoft Way
- Redmond, WA 98052, USA
- +1 425 882-8080
- anoopa@microsoft.com
-
- Michael Armijo
-
- Boreham et al Standards Track 10 \f
- LDAP Extensions for Scrolling View November 2001
- Browsing of Search Results
-
- Microsoft Corporation
- 1 Microsoft Way
- Redmond, WA 98052, USA
- +1 425 882-8080
- micharm@microsoft.com
-
Asaf Kashi
Microsoft Corporation
1 Microsoft Way
14. Full Copyright Statement
- Copyright (C) The Internet Society (2001). All Rights Reserved.
+ Copyright (C) The Internet Society (2002). 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
+ 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
+ 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."
+
+
+
+
+
+
+
-
-
-
-
- Boreham et al Standards Track 11 \f
\ No newline at end of file
+ Boreham et al Internet-Draft 11
\ No newline at end of file
projects / openldap / blobdiff