draft-ietf-asid-ldapv3ext-03.txt   draft-ietf-asid-ldapv3ext-04.txt 
ASID Working Group Y. Yaacovi ASID Working Group Y. Yaacovi
INTERNET-DRAFT Microsoft INTERNET-DRAFT Microsoft
M. Wahl M. Wahl
Critical Angle Inc. Critical Angle Inc.
K. Settle
Microsoft
T. Genovese T. Genovese
Microsoft Microsoft
Intended Category: Standards Track Intended Category: Standards Track
Lightweight Directory Access Protocol: Lightweight Directory Access Protocol (v3):
Extensions for Dynamic Directory Services Extensions for Dynamic Directory Services
<draft-ietf-asid-ldapv3ext-03.txt> <draft-ietf-asid-ldapv3ext-04.txt>
1. Status of this Memo 1. Status of this Memo
This document is an Internet-Draft. Internet-Drafts are working This document is an Internet-Draft. Internet-Drafts are working
documents of the Internet Engineering Task Force (IETF), its areas, documents of the Internet Engineering Task Force (IETF), its areas,
and its working groups. Note that other groups may also distribute and its working groups. Note that other groups may also distribute
working documents as Internet-Drafts. working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
skipping to change at line 47 skipping to change at line 45
for supporting client-server interoperation in a dynamic directories for supporting client-server interoperation in a dynamic directories
environment. environment.
The Lightweight Directory Access Protocol (LDAP) [1] supports The Lightweight Directory Access Protocol (LDAP) [1] supports
lightweight access to static directory services, allowing relatively lightweight access to static directory services, allowing relatively
fast search and update access. Static directory services store fast search and update access. Static directory services store
information about people that persists in its accuracy and value over information about people that persists in its accuracy and value over
a long period of time. a long period of time.
Dynamic directory services are different in that they store Dynamic directory services are different in that they store
information about people that only persists in its accuracy and value information that only persists in its accuracy and value when it is
when it is being periodically refreshed. This information is stored being periodically refreshed. This information is stored as dynamic
as dynamic entries and/or dynamic attributes. A typical use will be a entries in the directory. A typical use will be a client or a person
client or a person that is either online - in which case it has an that is either online - in which case it has an entry in the
entry or attributes in the directory, or is offline - in which case directory, or is offline - in which case its entry disappears from the
its entry or attributes disappear from the directory. Though the directory. Though the protocol operations and attributes used by
protocol operations and attributes used by dynamic directory services dynamic directory services are similar to the ones used for static
are similar to the ones used for static directory services, clients directory services, clients that store dynamic information in the
that store dynamic information in the directory need to periodically directory need to periodically refresh this information, in order to
refresh this information, in order to prevent it from disappearing. prevent it from disappearing. If dynamic entries are not refreshed
If dynamic entries or attributes are not refreshed within a given within a given timeout, they will be removed from the directory. For
timeout, they will be removed from the directory. For example, this example, this will happen if the client that set them goes offline.
will happen if the client that set them goes offline.
In addition, static directories may include dynamic information, in
the form of dynamic attributes in an otherwise static entry. Such
information needs to be refreshed periodically in the same manner.
A flow control mechanism from the server is also described that allows A flow control mechanism from the server is also described that allows
a server to inform clients how often they should refresh their a server to inform clients how often they should refresh their
presence. presence.
3. Requirements 3. Requirements
The protocol extensions must allow accessing dynamic information in a The protocol extensions must allow accessing dynamic information in a
directory in a standard LDAP manner, to allow clients to access static directory in a standard LDAP manner, to allow clients to access static
and dynamic information in the same way. and dynamic information in the same way.
By definition, dynamic entries or dynamic attributes are not By definition, dynamic entries are not persistent and clients may go
persistent and clients may go away gracefully or not. The proposed away gracefully or not. The proposed extensions must offer a way for
extensions must offer a way for a server to tell if entries or a server to tell if entries are still valid, and to do this in a way
attributes are still valid, and to do this in a way that is scalable. that is scalable. There also must be a mechanism for clients to
There also must be a mechanism for clients to reestablish their entry reestablish their entry with the server.
or attributes with the server.
There must be a way for clients to find out, in a standard LDAP
manner, if servers support the dynamic extensions.
Finally, to allow clients to broadly use the dynamic extensions, the Finally, to allow clients to broadly use the dynamic extensions, the
extensions need to be registered as standard LDAP extended operations. extensions need to be registered as standard LDAP extended operations.
4. Description of Approach 4. Description of Approach
The Lightweight Directory Access Protocol (LDAP) [1] permits The Lightweight Directory Access Protocol (LDAP) [1] permits
additional operation requests and responses to be added to the additional operation requests and responses to be added to the
protocol. This proposal takes advantage of these to support protocol. This proposal takes advantage of these to support
directories which contain dynamic information in a manner which directories which contain dynamic information in a manner which is
is fully integrated with LDAP. fully integrated with LDAP.
The approach described in this proposal defines dynamic entries and The approach described in this proposal defines dynamic entries in
dynamic attributes in order to allow implementing directories with order to allow implementing directories with dynamic information. An
dynamic information. An implementation of dynamic directories, must implementation of dynamic directories, must be able to support dynamic
be able to support both dynamic directory entries and dynamic directory entries.
attributes.
4.1. Dynamic Entries and the dynamicObject object class 4.1. Dynamic Entries and the dynamicObject object class
A dynamic entry is an object in the directory tree which has a A dynamic entry is an object in the directory tree which has a
time-to-live associated with it. This time-to-live is set when the time-to-live associated with it. This time-to-live is set when the
entry is created. The time-to-live is automatically decremented, and entry is created. The time-to-live is automatically decremented, and
when it expires the dynamic entry disappears. By invoking the refresh when it expires the dynamic entry disappears. By invoking the refresh
extended operation (defined below) to re-set the time-to-live, a extended operation (defined below) to re-set the time-to-live, a
client can cause the entry to remain present a while longer. client can cause the entry to remain present a while longer.
A dynamic entry is created by including the objectClass value given in A dynamic entry is created by including the objectClass value given in
section 6 in the list of attributes when adding an entry. This method section 6 in the list of attributes when adding an entry. This method
is subject to standard access control restrictions. is subject to standard access control restrictions.
The extended operation covered here, allows a client to refresh a The extended operation covered here, allows a client to refresh a
dynamic entry by invoking at intervals refresh operations containing dynamic entry by invoking, at intervals, refresh operations containing
that entry's name. Dynamic entries will be treated the same as that entry's name. Dynamic entries will be treated the same as
non-dynamic entries when processing search, compare, add, delete, non-dynamic entries when processing search, compare, add, delete,
modify and modifydn operations. However if clients stop sending modify and modifyDN operations. However if clients stop sending
refresh operations for an entry, then the server will automatically refresh operations for an entry, then the server will automatically
and without notification remove that entry from the directory. This and without notification remove that entry from the directory. This
removal will be treated the same as if the entry had been deleted by removal will be treated the same as if the entry had been deleted by
an LDAP protocol operation. an LDAP protocol operation.
There is no way to change a static entry into a dynamic one and vice- There is no way to change a static entry into a dynamic one and vice-
versa. If the client is using Modify with an objectClass of versa. If the client is using Modify with an objectClass of
dynamicObject on a static entry, the server must return a service dynamicObject on a static entry, the server must return a service
error either "objectClassModsProhibited" (if the server does not allow error either "objectClassModsProhibited" (if the server does not allow
objectClass modifications at all) or "objectClassViolation" (if the objectClass modifications at all) or "objectClassViolation" (if the
server does allow objectClass modifications in general). server does allow objectClass modifications in general).
A dynamic entry may be removed by the client using the delete A dynamic entry may be removed by the client using the delete
operation. This operation will be subject to access control operation. This operation will be subject to access control
restrictions. restrictions.
A non-dynamic entry cannot be added subordinate to a dynamic entry: A non-dynamic entry cannot be added subordinate to a dynamic entry:
the server must return an appropriate update or service error if this the server must return an appropriate update or service error if this
is attempted. is attempted.
4.2. Dynamic Attributes The support of dynamic attributes of an otherwise static object, are
outside the scope of this document.
A similar concept is dynamic attributes. These attributes behave the
same as ordinary user attributes to Search, Compare and Modify
requests, except that if they time out they disappear from the entry
in which they are located. (Unlike the dynamicObject class, the entry
itself does not disappear, and non-dynamic attributes are unaffected).
Like dynamic entries, a static entry with dynamic attributes must have
the entryTtl attribute which is described in section 6 below.
Dynamic attributes do not necessarily introduce a new set of
attributes in the schema. Any static attribute in the schema can be
made dynamic by including the ;dynamic attribute modifier with the
typename. It is allowed to introduce new dynamic attributes which are
not useful in the static domain. Such attributes will still require
including the ;dynamic attribute modifier with the typename to define
them as dynamic.
A dynamic attribute may be a subtype of a non-dynamic attribute, but a
non-dynamic attribute must not be a subtype of a dynamic attribute.
Operational attributes and collective attributes must not be dynamic.
All dynamic attributes are considered to be user attributes, however
they are not guaranteed to be present in shadow copies of entries.
A client may introduce dynamic attributes into an entry by using a
Modify request to add them, or by including them in the attribute list
of an Add Request. If the attribute type is permitted in the entry
then the dynamic attribute is also permitted. The client would
specify that the attribute is dynamic by including the tag ";dynamic"
with the typename. Dynamic values may be changed, and the attributes
removed, by using the Modify request as normal. If the entry is
deleted, dynamic attributes disappear immediately along with all the
non-dynamic. A ;dynamic modifier on an attribute may not be used in a
compare request, or in a search request (either in the filter or
attributes requested for return). This is in keeping with the
philosophy that dynamic attributes be indistinguishable from static
attributes as much as possible. In such a case, a server is expected
to reject the request, returning 'invalidAttributeSyntax'.
The granularity of a dynamic attribute is the entire attribute
including all values. Dynamic and static values may not be mixed
within a single attribute. For example, suppose an existing static
entry had an attribute called "ipAddress" with the value "1.2.3.4". A
modification of the entry to add the value "5.4.3.2" to the attribute
"ipAddress;dynamic" would fail with a "constraintViolation" error.
The addition and modification of dynamic attributes are subject to 4.2 Dynamic meetings (conferences)
schema and access control restrictions, as with non-dynamic
attributes. Thus unless the extensibleObject object class is present,
generally an object class or content rule must be defined to permit
those attributes to be present in an entry. If their presence is
controlled by an object class, then just as with non-dynamic
attributes, the object class value must have already been added before
the attributes are added. The dynamicObject object class described in
section 4.1 does not itself permit any particular dynamic attributes.
Dynamic attributes in a particular entry are refreshed using the The way dynamicObject is defined, it has a time-to-live associated
Refresh extended operation. All of the entry's dynamic attributes are with it, and that's about it. Though the most common dynamic object
refreshed by a single refresh request. The TTL given in the refresh is a person object, there is no specific type associated with the
response applies to all of the entry's dynamic attributes. There is dynamicObject as defined here. By the use of the dynamic object's
no way to refresh particular dynamic attributes within an entry at attributes, one can make this object represent practically anything.
different times, or to have different TTLs apply to different dynamic
attributes.
If not refreshed, all dynamic attributes in an entry time out Specifically, Meetings (conferences) can be represented by dynamic
simultaneously. All the attributes which are dynamic with all their objects. While full-featured meeting support requires special
values disappear atomically, as if the server had done a ModifyEntry semantics and handling by the server (and is not in the scope of this
specifying that all the dynamic types were to be deleted from that document), the extensions described here, provide basic meetings
entry. The client must not expect any dynamic attributes to be support. A meeting object can be refreshed by the meeting
present in an entry after the time-to-live for that entry has reached participants, and when it is not, the meeting entry disappears. The
zero. However the attributes may not disappear immediately as servers one meeting type that is naturally supported by the dynamic extensions
may only process timing out attributes at intervals (e.g. every few is creator-owned meeting.
minutes).
Note that if an object class definition references a dynamic attribute 4.2.1 Creator-owned meetings
as a mandatory attribute, the entry will still time out, but a schema
inconsistency will be present in that entry. (The objectClass
attribute and its values always remain since objectClass is not a
dynamic attribute.) Thus it is strongly recommended that designers not
specify dynamic attributes as anything other than optional attributes
of auxiliary classes.
Dynamic attributes may be used within dynamic entries (i.e., entries Creator-owned meetings are created by a client that sets the
containing object class "dynamicObject", defined below), but since all time-to-live attribute for the entry, and it is this client's
of such an entry's attributes are implicitly dynamic, such use is responsibility to refresh the meeting entry, so that it will not
superfluous. disappear. Others might join the meeting, by modifying the
appropriate attribute, but they are not allowed to refresh the entry.
When the client that created the entry goes away, it can delete the
meeting entry, or it might disappear when its time-to-live expires.
This is consistent with the common model for dynamicObject as
described above.
5. Protocol Additions 5. Protocol Additions
5.1 Refresh Request 5.1 Refresh Request
Refresh is a protocol operation sent by a client to tell the server Refresh is a protocol operation sent by a client to tell the server
that the client is still alive and the dynamic directory entry or the that the client is still alive and the dynamic directory entry is
dynamic attributes of the entry are still accurate and valuable. The still accurate and valuable. The client sends a Refresh request
client sends a Refresh request periodically based on the value of the periodically based on the value of the client refresh period (CRP).
client refresh period (CRP). The server can request that the client The server can request that the client change this value. As long as
change this value. As long as the server receives a Refresh request the server receives a Refresh request within the timeout period, the
within the timeout period, the directory entry is guaranteed to directory entry is guaranteed to persist on the server. Client
persist on the server. Clients implementers should be aware that implementers should be aware that since the intervening network
since the intervening network between the client and server is between the client and server is unreliable, a Refresh request packet
unreliable, a Refresh request packet may be delayed or lost while in may be delayed or lost while in transit. If this occurs, the entry
transit. If this occurs, the entry or the dynamic attributes may may disappear, and the client will need to detect this and re-add the
disappear, and the client will need to detect this and re-add the entry.
entry or the attributes.
A client may request this operation by transmitting an LDAP PDU A client may request this operation by transmitting an LDAP PDU
containing an ExtendedRequest. An LDAP ExtendedRequest is defined as containing an ExtendedRequest. An LDAP ExtendedRequest is defined as
follows: follows:
ExtendedRequest ::= [APPLICATION 23] SEQUENCE { ExtendedRequest ::= [APPLICATION 23] SEQUENCE {
requestName [0] LDAPOID, requestName [0] LDAPOID,
requestValue [1] OCTET STRING } requestValue [1] OCTET STRING }
The requestName field must be set to the string The requestName field must be set to the string
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The requestValue field will contain as a value the DER-encoding of the The requestValue field will contain as a value the DER-encoding of the
following ASN.1 data type: following ASN.1 data type:
SEQUENCE { SEQUENCE {
entryName [0] LDAPDN, entryName [0] LDAPDN,
requestTtl [1] INTEGER requestTtl [1] INTEGER
} }
The entryName field is the UTF-8 string representation of the name of The entryName field is the UTF-8 string representation of the name of
the dynamic entry or the entry containing dynamic attributes [3]. the dynamic entry [3].
This entry must already exist. This entry must already exist.
The requestTtl is a time in seconds (between 1 and 31557600) that the The requestTtl is a time in seconds (between 1 and 31557600) that the
client requests that the entry or the dynamic attributes exists in the client requests that the entry exists in the directory before being
directory before being automatically removed. Servers are not automatically removed. Servers are not required to accept this value
required to accept this value and might return a different TTL value and might return a different TTL value to the client. Clients must be
to the client. Clients must be able to use this server-dictated value able to use this server-dictated value as their CRP.
as their CRP.
5.2 Refresh Response 5.2 Refresh Response
If a server implements this extension, then when the request is made If a server implements this extension, then when the request is made
it will return an LDAP PDU containing an ExtendedResponse. An LDAP it will return an LDAP PDU containing an ExtendedResponse. An LDAP
ExtendedResponse is defined as follows: ExtendedResponse is defined as follows:
ExtendedResponse ::= [APPLICATION 24] SEQUENCE { ExtendedResponse ::= [APPLICATION 24] SEQUENCE {
responseName [0] LDAPOID OPTIONAL, responseName [0] LDAPOID OPTIONAL,
response [1] OCTET STRING OPTIONAL, response [1] OCTET STRING OPTIONAL,
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The response field will contain as a value the DER-encoding of the The response field will contain as a value the DER-encoding of the
following ASN.1 data type: following ASN.1 data type:
SEQUENCE { SEQUENCE {
responseTtl [1] INTEGER responseTtl [1] INTEGER
} }
The responseTtl field is the time in seconds which the server chooses The responseTtl field is the time in seconds which the server chooses
to have as the time-to-live field for that entry. It must not be any to have as the time-to-live field for that entry. It must not be any
smaller than that which the client requested, and it may be larger. smaller than that which the client requested, and it may be larger.
Please note that for the case of a static entry with dynamic
attributes, this time-to-live applies to all the dynamic attributes in
this entry.
If the operation was successful, the errorCode field in the If the operation was successful, the errorCode field in the
standardResponse part of an ExtendedResponse will be set to success. standardResponse part of an ExtendedResponse will be set to success.
In case of an error, the responseTtl field will have the value 0, and In case of an error, the responseTtl field will have the value 0, and
the errorCode field will contain an appropriate value, as follows: If the errorCode field will contain an appropriate value, as follows: If
the entry named by entryName could not be located, the errorCode field the entry named by entryName could not be located, the errorCode field
will contain "noSuchObject". If the entry is not dynamic, or does not will contain "noSuchObject". If the entry is not dynamic, the
have dynamic attributes, the errorCode field will contain errorCode field will contain "objectClassViolation". If the requester
"objectClassViolation". If the requester does not have permission to does not have permission to refresh the entry, the errorCode field
refresh the entry, the errorCode field will contain will contain "insufficientAccessRights". If the requestTtl field is
"insufficientAccessRights". If the requestTtl field is too large, the too large, the errorCode field will contain "sizeLimitExceeded".
errorCode field will contain "sizeLimitExceeded".
If a server does not implement this extension, it will return an LDAP If a server does not implement this extension, it will return an LDAP
PDU containing an ExtendedResponse, which contains only the PDU containing an ExtendedResponse, which contains only the
standardResponse element (the responseName and response elements will standardResponse element (the responseName and response elements will
be absent). The LDAPResult element will indicate the protocolError be absent). The LDAPResult element will indicate the protocolError
result code. result code.
This request is permitted to be invoked when LDAP is carried by a This request is permitted to be invoked when LDAP is carried by a
connectionless transport. connectionless transport.
When using a connection-oriented transport, there is no requirement When using a connection-oriented transport, there is no requirement
that this operation be on the same particular connection as any other. that this operation be on the same particular connection as any other.
A client may open multiple connections, or close and then reopen a A client may open multiple connections, or close and then reopen a
connection. connection.
6. Schema Additions 6. Schema Additions
All dynamic entries must have the dynamicObject value in their All dynamic entries must have the dynamicObject value in their
objectClass attribute. This object class is defined as follows objectClass attribute. This object class is defined as follows (using
(using the ObjectClassDescription notation of [2]): the ObjectClassDescription notation of [2]):
( 1.3.6.1.4.1.1466.101.119.2 NAME 'dynamicObject' ( 1.3.6.1.4.1.1466.101.119.2 NAME 'dynamicObject'
DESC 'This class, if present in an entry, indicates that this entry DESC 'This class, if present in an entry, indicates that this entry
has a limited lifetime and may disappear automatically when has a limited lifetime and may disappear automatically when
its time-to-live has reached 0. There are no mandatory its time-to-live has reached 0. There are no mandatory
attributes of this class, however if the client has not attributes of this class, however if the client has not
supplied a value for the entryTtl attribute, the server will supplied a value for the entryTtl attribute, the server will
provide one.' provide one.'
SUP top AUXILIARY ) SUP top AUXILIARY )
Furthermore, the dynamic entry or the static entry with dynamic Furthermore, the dynamic entry must have the following operational
attributes must have the following operational attribute. It is attribute. It is described using the AttributeTypeDescription
described using the AttributeTypeDescription notation of [2]: notation of [2]:
( 1.3.6.1.4.1.1466.101.119.3 NAME 'entryTtl' ( 1.3.6.1.4.1.1466.101.119.3 NAME 'entryTtl'
DESC 'This operational attribute is maintained by the server and DESC 'This operational attribute is maintained by the server and
appears to be present in every dynamic entry or an entry that appears to be present in every dynamic entry. The attribute
contains dynamic attributes. The attribute is not present is not present when the entry does not contain the dynamicObject
when the entry does not contain the dynamicObject object class object class. The value of this attribute is the time in seconds
or dynamic attributes. The value of this attribute is the that the entry will continue to exist before disappearing from
time in seconds that the entry or the dynamic attributes in a
static entry will continue to exist before disappearing from
the directory. In the absence of intervening refresh the directory. In the absence of intervening refresh
operations, the values returned by reading the attribute in operations, the values returned by reading the attribute in
two successive searches are guaranteed to be nonincreasing. two successive searches are guaranteed to be nonincreasing.
The smallest permissible value is 0, indicating that the entry The smallest permissible value is 0, indicating that the entry
may disappear without warning. The attribute is marked may disappear without warning. The attribute is marked
NO-USER-MODIFICATION since it may only be changed using the NO-USER-MODIFICATION since it may only be changed using the
refresh operation.' refresh operation.'
SYNTAX 'Integer' SINGLE-VALUE NO-USER-MODIFICATION USAGE dSAOperation ) SYNTAX 'Integer' SINGLE-VALUE NO-USER-MODIFICATION USAGE dSAOperation )
To allow servers to support dynamic entries in only a part of the
DIT, the following operational attribute is defined. It is described
using the AttributeTypeDescription notation of [2]:
( 1.3.6.1.4.1.1466.101.119.4 NAME 'dynamicSubtrees'
DESC 'This operational attribute is maintained by the server and
is present in the Root DSE, if the server supports the dynamic
extensions described in this draft. The attribute contains a
list of all the subtrees in this directory for which the
server supports the dynamic extensions.'
SYNTAX 'DN' NO-USER-MODIFICATION USAGE dSAOperation )
7. Client and Server Requirements 7. Client and Server Requirements
7.1 Client Requirements 7.1 Client Requirements
Clients can find out if a server supports the dynamic extensions by
checking the supportedExtension field in the root DSE, to see if the
OBJECT IDENTIFIER described in section 5 is present. Since servers
may select to support the dynamic extensions in only some of the
subtrees of the DIT, clients must check the dynamicSubtrees
operational attribute in the root DSE to find out if the dynamic
extensions are supported on a specific subtree.
Once a dynamic entry has been created, clients are responsible for Once a dynamic entry has been created, clients are responsible for
invoking the refresh extended operation, in order to keep that entry invoking the refresh extended operation, in order to keep that entry
present in the directory. The same holds true for keeping dynamic present in the directory.
attributes present on a static entry.
Clients must not expect that a dynamic entry will be present in the Clients must not expect that a dynamic entry will be present in the
DIT after it has timed out, however it must not either require that DIT after it has timed out, however it must not require that the
the server remove the entry immediately (some servers may only process server remove the entry immediately (some servers may only process
timing out entries at intervals). If the client wishes to ensure the timing out entries at intervals). If the client wishes to ensure the
entry does not exist it should issue a RemoveRequest for that entry. entry does not exist it should issue a RemoveRequest for that entry.
Again, dynamic attributes behave the same: they will not be present in
the DIT after they timed out, but the client should not require their
immediate removal.
Initially, a client needs to know how often it should send refresh Initially, a client needs to know how often it should send refresh
requests to the server. This value is defined as the CRP (Client requests to the server. This value is defined as the CRP (Client
Refresh Period) and is set by the server based on the entryTtl. Since Refresh Period) and is set by the server based on the entryTtl. Since
the AddRequest is left unchanged and is not modified in this proposal the LDAP AddRequest operation is left unchanged and is not modified in
to return this value, a client must issue a Refresh extended operation this proposal to return this value, a client must issue a Refresh
immediately after an Add that created a dynamic entry. The Refresh extended operation immediately after an Add that created a dynamic
Response will return the CRP (in responseTtl) to the client. entry. The Refresh Response will return the CRP (in responseTtl)
to the client.
Clients must not issue the refresh request for dynamic entries which Clients must not issue the refresh request for dynamic entries which
they have not created or for static entries to which they did not add they have not created. Please note that servers which allow anonymous
dynamic attributes. Please note that when a client refreshes a static clients to create and refresh dynamic entries will not be able to
entry to which it added dynamic attribute(s), it refreshes ALL the
dynamic attributes in this entry, including ones added by other
clients. Also note that servers which allow anonymous clients to
create and refresh dynamic entries and attributes will not be able to
enforce the above. enforce the above.
Clients should always be ready to handle the case in which their entry Clients should always be ready to handle the case in which their entry
or dynamic attributes timed out. In such a case, the Refresh timed out. In such a case, the Refresh operation will fail with an
operation will fail with an error code such as noSuchObject, and the error code such as noSuchObject, and the client is expected to
client is expected to re-create its entry or re-add the dynamic re-create its entry.
attributes.
Clients should be prepared to experience refresh operations failing Clients should be prepared to experience refresh operations failing
with protocolError, even though the add and any previous refresh with protocolError, even though the add and any previous refresh
requests succeeded. This might happen if a proxy between the client requests succeeded. This might happen if a proxy between the client
and the server goes down, and another proxy is used which does not and the server goes down, and another proxy is used which does not
support the Refresh extended operation. support the Refresh extended operation.
7.2 Server Requirements 7.2 Server Requirements
Servers are responsible for removing dynamic entries and dynamic Servers are responsible for removing dynamic entries when they time
attributes when they time out. Servers are not required to do this out. Servers are not required to do this immediately.
immediately.
Servers must enforce the structural rules listed in above section 4. Servers must enforce the structural rules listed in above section 4.
Servers must ensure that the operational attribute described in Servers must ensure that the operational attribute described in
section 6 is present in dynamic entries or in static entries that section 6 is present in dynamic entries
contain dynamic attributes.
Servers are permitted to check the authentication of the client Servers are permitted to check the authentication of the client
invoking a refresh extended operation, and only permit the operation invoking a refresh extended operation, and only permit the operation
if it matches that of the client which created the dynamic entry or if it matches that of the client which created the dynamic entry
added dynamic attributes to this entry (please see a note about that (please see a note about that in section 7.1). Servers may permit
in section 7.1). Servers may permit anonymous users to refresh anonymous users to refresh entries.
entries.
Servers may require that a client which attempts to create a dynamic Servers may require that a client which attempts to create a dynamic
entry have a remove permission for that entry. entry have a remove permission for that entry.
Servers which implement this extension must have the OBJECT Servers which implement the dynamic extensions must have the OBJECT
IDENTIFIERs, described above in section 5 for the request and IDENTIFIER, described above in section 5 for the request and
response, present as values of the supportedExtension field in the response, present as a value of the supportedExtension field in the
root DSE. They must also have as values in the attributeTypes and root DSE. They must also have as values in the attributeTypes and
objectClasses attributes of their subschema subentries, the objectClasses attributes of their subschema subentries, the
AttributeTypeDescription and ObjectClassDescription from section 6. AttributeTypeDescription and ObjectClassDescription from section 6.
An implementation of dynamic directories, must be able to support both Servers can limit the support of the dynamic extensions to only
dynamic directory entries and dynamic attributes. some of the subtrees in the DIT. Servers indicate for which subtrees
they support the extensions, by specifying the OIDs for the
supported subtrees in the dynamicSubtrees attribute described in
section 6. If a server supports the dynamic extensions for all
naming contexts it holds, the dynamicSubtrees attribute may be
absent.
8. Implementation issues 8. Implementation issues
8.1 Storage of dynamic information 8.1 Storage of dynamic information
Dynamic information is expected to change very often. In addition, Dynamic information is expected to change very often. In addition,
Refresh requests are expected to arrive at the server very often. Refresh requests are expected to arrive at the server very often.
Disk-based databases that static directory services often use are Disk-based databases that static directory services often use are
likely inappropriate for storing dynamic information. We recommend likely inappropriate for storing dynamic information. We recommend
that server implementations store dynamic entries in memory sufficient that server implementations store dynamic entries in memory sufficient
to avoid paging. This is not a requirement. to avoid paging. This is not a requirement.
We expect LDAP servers to be able to store static and dynamic entries. We expect LDAP servers to be able to store static and dynamic entries.
If an LDAP server does not support dynamic entries, it should respond If an LDAP server does not support dynamic entries, it should respond
with an error code such as objectClassViolation. Such a server might with an error code such as objectClassViolation.
still support setting dynamic attributes on a static entry.
8.2 Client refresh behavior 8.2 Client refresh behavior
In some cases, the client might not get a Refresh response. This may In some cases, the client might not get a Refresh response. This may
happen as a result of a server crash after receiving the Refresh happen as a result of a server crash after receiving the Refresh
request, the TCP/IP socket timing out in the connection case, or the request, the TCP/IP socket timing out in the connection case, or the
UDP packet getting lost in the connection-less case. UDP packet getting lost in the connection-less case.
It is recommended that in such a case, the client will retry the It is recommended that in such a case, the client will retry the
Refresh operation immediately, and if this Refresh request does not Refresh operation immediately, and if this Refresh request does not
get a response as well, it will resort to its original Refresh cycle, get a response as well, it will resort to its original Refresh cycle,
i.e. send a Refresh request at its Client Refresh Period (CRP). i.e. send a Refresh request at its Client Refresh Period (CRP).
9. Localization 9. Replication
Replication is not addressed in this draft. There is a separate effort
in progress at the IETF on replication of static and dynamic directories.
10. Localization
The are no localization issues for this extended operation. The are no localization issues for this extended operation.
10. Security Considerations 11. Security Considerations
Security issues are not addressed in this document. Please note, Standard LDAP security rules and support apply for the extensions
though, that anonymous clients are able to refresh entries which they described in this document, and there are no special security issues
did not create. for these extensions. Please note, though, that servers may permit
anonymous clients to refresh entries which they did not create.
Also, Care should be taken in making use of information obtained from Also, Care should be taken in making use of information obtained from
directory servers that has been supplied by client, as it may now be directory servers that has been supplied by client, as it may now be
out of date. In many networks, for example, IP addresses are out of date. In many networks, for example, IP addresses are
automatically assigned when a host connects to the network, and may be automatically assigned when a host connects to the network, and may be
reassigned if that host later disconnects. An IP address obtained reassigned if that host later disconnects. An IP address obtained
from the directory may no longer be assigned to the host that placed from the directory may no longer be assigned to the host that placed
the address in the directory. This issue is not specific to LDAP or the address in the directory. This issue is not specific to LDAP or
dynamic directories. dynamic directories.
11. Acknowledgments 12. Acknowledgments
Design ideas included in this document are based on those discussed in Design ideas included in this document are based on those discussed in
ASID and other IETF Working Groups. ASID and other IETF Working Groups.
12. Authors Addresses 13. Authors Addresses
Yoram Yaacovi Yoram Yaacovi
Microsoft Microsoft
One Microsoft way One Microsoft way
Redmond, WA 98052 Redmond, WA 98052
USA USA
Phone: +1 206-936-9629 Phone: +1 206-936-9629
EMail: yoramy@microsoft.com EMail: yoramy@microsoft.com
Mark Wahl Mark Wahl
Critical Angle Inc. Critical Angle Inc.
4815 W. Braker Lane #502-385 4815 W. Braker Lane #502-385
Austin, TX 78759 Austin, TX 78759
USA USA
EMail: M.Wahl@critical-angle.com EMail: M.Wahl@critical-angle.com
Kent Settle
Microsoft
One Microsoft way
Redmond, WA 98052
USA
Phone: +1 206-936-3027
EMail: kentse@microsoft.com
Tony Genovese Tony Genovese
Microsoft Microsoft
One Microsoft way One Microsoft way
Redmond, WA 98052 Redmond, WA 98052
USA USA
Phone: +1 206-703-0852 Phone: +1 206-703-0852
EMail: tonyg@microsoft.com EMail: tonyg@microsoft.com
13. Bibliography 14. Bibliography
[1] M.Wahl, T. Howes, S. Kille, "Lightweight Directory Access [1] M.Wahl, T. Howes, S. Kille, "Lightweight Directory Access
Protocol (Version 3)". INTERNET DRAFT Protocol (Version 3)". INTERNET DRAFT
<draft-ietf-asid-ldapv3-protocol-01.txt> <draft-ietf-asid-ldapv3-protocol-04.txt>
[2] M.Wahl, A.Coulbeck, T. Howes, S. Kille, "Lightweight Directory [2] M.Wahl, A.Coulbeck, T. Howes, S. Kille, "Lightweight Directory
Access Protocol Standard and Pilot Attributes". INTERNET DRAFT Access Protocol (v3): Attribute Syntax Definitions". INTERNET DRAFT
<draft-ietf-asid-ldapv3-attributes-02.txt> <draft-ietf-asid-ldapv3-attributes-04.txt>
[3] M.Wahl, S.Kille, "Lightweight Directory Access Protocol UTF-8 [3] M.Wahl, S.Kille, "Lightweight Directory Access Protocol (v3):
String Representation of Distinguished Names". INTERNET DRAFT UTF-8 String Representation of Distinguished Names". INTERNET DRAFT
<draft-ietf-asid-ldapv3-dn-00.txt> <draft-ietf-asid-ldapv3-dn-02.txt>
Expires on six months from the post date (see top). Expires on six months from the post date (see top).
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