Network Working Group M.T. Rose
Internet-Draft Invisible Worlds, Inc.
Expires: June 20, 2001 G. Klyne
Content Technologies Limited
D.H. Crocker
Brandenburg Consulting
December 20, 2000
The APEX Presence Service
draft-mrose-apex-presence-00
Status of this Memo
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Copyright Notice
Copyright (C) The Internet Society (2000). All Rights Reserved.
Abstract
This memo describes the APEX presence service, addressed as the
well-known endpoint "apex=presence". The presence service is used to
manage presence information for APEX endpoints.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Management of Presence Information . . . . . . . . . . . . . . 4
2.1 Update of Presence Information . . . . . . . . . . . . . . . . 5
2.2 Distribution of Presence Information . . . . . . . . . . . . . 6
2.3 Distribution of Watcher Information . . . . . . . . . . . . . 9
3. Format of Presence Entries . . . . . . . . . . . . . . . . . . 12
4. The Presence Service . . . . . . . . . . . . . . . . . . . . . 13
4.1 Use of XML and MIME . . . . . . . . . . . . . . . . . . . . . 14
4.2 The Subscribe Operation . . . . . . . . . . . . . . . . . . . 15
4.3 The Watch Operation . . . . . . . . . . . . . . . . . . . . . 17
4.4 The Publish Operation . . . . . . . . . . . . . . . . . . . . 19
4.5 The Terminate Operation . . . . . . . . . . . . . . . . . . . 21
4.6 The Notify Operation . . . . . . . . . . . . . . . . . . . . . 22
4.7 The Reply Operation . . . . . . . . . . . . . . . . . . . . . 22
5. Registration: The Presence Service . . . . . . . . . . . . . . 23
6. The Presence Service DTD . . . . . . . . . . . . . . . . . . . 24
References . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 27
A. Changes from IMXP . . . . . . . . . . . . . . . . . . . . . . 28
Full Copyright Statement . . . . . . . . . . . . . . . . . . . 29
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1. Introduction
This memo describes a presence service that is built upon the
APEX[1] "relaying mesh". The APEX presence service is used to manage
presence information for APEX endpoints.
APEX, at its core, provides a best-effort datagram service. Although
additional APEX services are co-resident with each relay within an
administrative domain, they are logically provided on top of the
relaying mesh, i.e.,
+----------+ +----------+ +----------+ +---------+
| APEX | | APEX | | APEX | | |
| access | | presence | | report | | ... |
| service | | service | | service | | |
+----------+ +----------+ +----------+ +---------+
| | | |
| | | |
+----------------------------------------------------------------+
| |
| APEX core |
| |
+----------------------------------------------------------------+
That is, applications communicate with an APEX service by exchanging
data with a "well-known endpoint" (WKE).
APEX applications communicate with the presence service by
exchanging data with the well-known endpoint "apex=presence" in the
corresponding administrative domain, e.g.,
"apex=presence@example.com" is the endpoint associated with the
presence service in the "example.com" administrative domain.
Note that within a single administrative domain, the presence
service makes use of the APEX access[3] service in order to
determine if an originator is allowed to view or manage presence
information.
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2. Management of Presence Information
Management of presence information falls into three categories:
o applications may update the presence entry associated with an
endpoint;
o applications may subscribe to receive presence information about
an endpoint; and,
o applications may find out who is subscribed to receive presence
information.
Each is now described in turn.
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2.1 Update of Presence Information
When an application wants to modify the presence entry associated
with an endpoint, it sends a publish operation to the service, e.g.,
+-------+ +-------+
| | -- data -------> | |
| appl. | | relay |
| | <--------- ok -- | |
+-------+ +-------+
C: <data content='#Content'>
<originator identity='fred@example.com' />
<recipient identity='apex=presence@example.com' />
<data-content Name='Content'>
<publish publisher='fred@example.com' transID='1'
timeStamp='14 May 2000 13:30:00 -0800'>
<presence publisher='fred@example.com'
lastUpdate='14 May 2000 13:02:00 -0800'
publisherInfo='http://www.example.com/fred/'>
<tuple destination='im:fred@example.com'
availableUntil='14 May 2000 14:02:00 -0800' />
<tuple destination='mailto:fred@flintstone.com'
availableUntil='31 Dec 2525 23:59:59 -0800' />
</presence>
</publish>
</data-content>
</data>
S: <ok />
The service immediately responds with a reply operation containing
the same transaction-identifier, e.g.,
+-------+ +-------+
| | <------- data -- | |
| relay | | pres. |
| | -- ok ---------> | svc. |
+-------+ +-------+
C: <data content='#Content'>
<originator identity='apex=presence@example.com' />
<recipient identity='fred@example.com' />
<data-content Name='Content'>
<reply code='250' transID='1' />
</data-content>
</data>
S: <ok />
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2.2 Distribution of Presence Information
When an application wants to (periodically) receive the presence
entry associated with an endpoint, it sends a subscribe operation to
the service, e.g.,
+-------+ +-------+
| | -- data -------> | |
| appl. | | relay |
| | <--------- ok -- | |
+-------+ +-------+
C: <data content='#Content'>
<originator identity='wilma@example.com' />
<recipient identity='apex=presence@example.com' />
<data-content Name='Content'>
<subscribe publisher='fred@example.com' duration='86400'
transID='100' />
</data-content>
</data>
S: <ok />
The service immediately responds with a publish operation containing
the same transaction-identifier, e.g.,
+-------+ +-------+
| | <------- data -- | |
| relay | | pres. |
| | -- ok ---------> | svc. |
+-------+ +-------+
C: <data content='#Content'>
<originator identity='apex=presence@example.com' />
<recipient identity='wilma@example.com' />
<data-content Name='Content'>
<publish publisher='fred@example.com' transID='100'
timeStamp='14 May 2000 13:30:00 -0800'>
<presence publisher='fred@example.com'
lastUpdate='14 May 2000 13:02:00 -0800'
publisherInfo='http://www.example.com/fred/'>
<tuple destination='im:fred@example.com'
availableUntil='14 May 2000 14:02:00 -0800' />
</presence>
</publish>
</data-content>
</data>
S: <ok />
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Subsequently, for up to the specified "duration", the service sends
new publish operations whenever there are any changes to the
endpoint's presence information. If the "duration" is zero-valued, a
one time poll of the presence information is achieved; otherwise, at
the end of the "duration", a terminate operation is sent.
Note that Step 5 of Section 4.4 requires that the timestamp field of
a presence entry be supplied in order to update that entry;
accordingly, applications must successfully retrieve an publish
entry prior to trying to update that entry. This is usually
accomplished by subscribing with a zero-valued duration.
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Either the subscriber or the service may cancel a subscription by
sending a terminate operation, e.g.,
+-------+ +-------+
| | -- data -------> | |
| appl. | | relay |
| | <--------- ok -- | |
+-------+ +-------+
C: <data content='#Content'>
<originator identity='wilma@example.com' />
<recipient identity='apex=presence@example.com' />
<data-content Name='Content'>
<terminate transID='100' />
</data-content>
</data>
S: <ok />
+-------+ +-------+
| | <------- data -- | |
| relay | | pres. |
| | -- ok ---------> | svc. |
+-------+ +-------+
C: <data content='#Content'>
<originator identity='apex=presence@example.com' />
<recipient identity='wilma@example.com' />
<data-content Name='Content'>
<reply code='250' transID='100' />
</data-content>
</data>
S: <ok />
or
+-------+ +-------+
| | <------- data -- | |
| relay | | pres. |
| | -- ok ---------> | svc. |
+-------+ +-------+
C: <data content='#Content'>
<originator identity='apex=presence@example.com' />
<recipient identity='wilma@example.com' />
<data-content Name='Content'>
<terminate transID='100' />
</data-content>
</data>
S: <ok />
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2.3 Distribution of Watcher Information
When an application wants to (periodically) receive notices about
endpoints that are subscribed to receive presence information, it
sends a watch operation to the service, e.g.,
+-------+ +-------+
| | -- data -------> | |
| appl. | | relay |
| | <--------- ok -- | |
+-------+ +-------+
C: <data content='#Content'>
<originator identity='fred@example.com' />
<recipient identity='apex=presence@example.com' />
<data-content Name='Content'>
<watch publisher='fred@example.com' duration='86400'
transID='2' />
</data-content>
</data>
S: <ok />
The service immediately responds with a reply operation containing
the same transaction-identifier, e.g.,
+-------+ +-------+
| | <------- data -- | |
| relay | | pres. |
| | -- ok ---------> | svc. |
+-------+ +-------+
C: <data content='#Content'>
<originator identity='apex=presence@example.com' />
<recipient identity='fred@example.com' />
<data-content Name='Content'
<reply code='250' transID='2' />
</data-content>
</data>
S: <ok />
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For each current subscriber, the service immediately sends a notify
operation containing the same transaction-identifier, e.g.,
+-------+ +-------+
| | <------- data -- | |
| relay | | pres. |
| | -- ok ---------> | svc. |
+-------+ +-------+
C: <data content='#Content'>
<originator identity='apex=presence@example.com' />
<recipient identity='fred@example.com' />
<data-content Name='Content'>
<notify subscriber='wilma@example.com' transID='2' />
</data-content>
</data>
S: <ok />
Subsequently, for up to the specified "duration", the service sends
new notify operations whenever an application subscribes
successfully. If the "duration" is zero-valued, a one time poll of
the watcher information is achieved; otherwise, at the end of the
"duration", a terminate operation is sent.
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Either the watcher or the service may cancel the request by sending
a terminate operation, e.g.,
+-------+ +-------+
| | -- data -------> | |
| appl. | | relay |
| | <--------- ok -- | |
+-------+ +-------+
C: <data content='#Content'>
<originator identity='fred@example.com' />
<recipient identity='apex=presence@example.com' />
<data-content Name='Content'>
<terminate transID='2' />
</data-content>
</data>
S: <ok />
+-------+ +-------+
| | <------- data -- | |
| relay | | pres. |
| | -- ok ---------> | svc. |
+-------+ +-------+
C: <data content='#Content'>
<originator identity='apex=presence@example.com' />
<recipient identity='fred@example.com' />
<data-content Name='Content'>
<reply code='250' transID='2' />
</data-content>
</data>
S: <ok />
or
+-------+ +-------+
| | <------- data -- | |
| relay | | pres. |
| | -- ok ---------> | svc. |
+-------+ +-------+
C: <data content='#Content'>
<originator identity='apex=presence@example.com' />
<recipient identity='fred@example.com' />
<data-content Name='Content'>
<terminate transID='2' />
</data-content>
</data>
S: <ok />
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3. Format of Presence Entries
Each administrative domain is responsible for maintaining a
"presence entry" for each of its endpoints (regardless of whether
those endpoints are currently attached to the relaying mesh).
Section 6 defines the syntax for presence entries. Each presence
entry has a "publisher" attribute, a "lastUpdate" attribute, a
"publisherInfo" attribute, and contains one or more "tuple"
elements:
o the "publisher" attribute specifies the endpoint associated with
the presence entry;
o the "lastUpdate" attribute specifies the date and time that the
service last updated the presence entry;
o the "publisherInfo" attribute specifies arbitrary information
about the publisher (using a URI); and,
o each "tuple" element specifies information about an entity
associated with the endpoint.
Each "tuple" element has a "destination" attribute, an
"availableUntil" attribute, a "tupleInfo" attribute, and contains
zero or more "capability" elements:
o the "destination" attribute identifies the entity as a URI (e.g.,
"im:fred@example.com" or "mailto:fred@flintstone.com");
o the "availableUntil" attribute specifies the latest date and time
that the entity is capable of receiving messages;
o the "tupleInfo" attribute specifies arbitrary information about
the entity (using a URI); and,
o each "capability" element contains a specification as to the
kinds of content the entity is capable of receiving.
Each "capability" element contains arbitrary character data
formatted according to the standard indicated in the element's
"baseline" attribute.
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4. The Presence Service
Section 5 contains the APEX service registration for the presence
service:
o Within an administrative domain, the service is addressed using
the well-known endpoint of "apex=presence".
o Section 6 defines the syntax of the operations exchanged with the
service.
o A consumer of the service initiates communications by sending
data containing the subscribe, watch, or publish operation.
o In addition to replying to these operations, the service may also
initiate communications by sending data containing the terminate,
publish, or notify operations.
An implementation of the service must maintain information about
both presence entries and in-progress operations in persistent
storage.
Consult Section 6.1.1 of [1] for a discussion on the properties of
long-lived transaction-identifiers.
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4.1 Use of XML and MIME
Section 4.1 of [1] describes how arbitrary MIME content is exchanged
as a BEEP[2] payload. For example, to transmit:
<data content='...'>
<originator identity='apex=presence@example.com' />
<recipient identity='fred@example.com' />
</data>
where "..." refers to: <reply code='250' transID='1' />
then the corresponding BEEP message might look like this:
C: MSG 1 1 . 42 1234
C: Content-Type: multipart/related; boundary="boundary";
C: start="<1@example.com>";
C: type="application/beep+xml"
C:
C: --boundary
C: Content-Type: application/beep+xml
C: Content-ID: <1@example.com>
C:
C: <data content='cid:2@example.com'>
C: <originator identity='fred@example.com' />
C: <recipient identity='apex=presence@example.com' />
C: </data>
C: --boundary
C: Content-Type: application/beep+xml
C: Content-Transfer-Encoding: binary
C: Content-ID: <2@example.com>
C:
C: <reply code='250' transID='1' />
C: --boundary--
C: END
or this:
C: MSG 1 1 . 42 1234
C: Content-Type: application/beep+xml
C:
C: <data content='#Content'>
C: <originator identity='fred@example.com' />
C: <recipient identity='apex=presence@example.com' />
C: <data-content Name='Content'>
C: <reply code='250' transID='1' />
C: </data-content>
C: </data>
C: END
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4.2 The Subscribe Operation
When an application wants to (periodically) receive the presence
entry associated with an endpoint, it sends a "subscribe" element to
the service.
The "subscribe" element has a "publisher" attribute, a "duration"
attribute, a "transID" attribute, and no content:
o the "publisher" attribute specifies the endpoint associated with
the presence entry;
o the "transID" attribute specifies the transaction-identifier
associated with this operation; and,
o the "duration" attribute specifies the maximum number of seconds
for which the originator is interested in receiving updated
presence information.
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When the service receives a "subscribe" element, we refer to the
"publisher" attribute of that element as the "subject", and the
service performs these steps:
1. If the subject is outside of this administrative domain, a
"reply" element having code 553 is sent as data to the
originator.
2. If the subject does not refer to a valid endpoint, a "reply"
element having code 550 is sent as data to the originator.
3. If the subject's access entry does not contain a
"presence:subscribe" token for the originator, a "reply" element
having code 537 is sent as data to the originator.
4. If the originator already has an in-progress subscribe operation
for the subject, then the previous subscribe operation is
silently terminated, and processing continues.
5. If the "transID" attribute refers to an in-progress subscribe or
watch operation for the originator, a "reply" element having
code 555 is sent as data to the originator.
6. Otherwise:
1. A "publish" element, corresponding to the subject's presence
entry, is immediately sent as data to the originator.
2. For each endpoint currently watching subscribers to the
subject's presence information, a "notify" element is
immediately as sent as data (c.f., Step 6.3 of Section 4.6).
3. For up to the amount of time indicated by the "duration"
attribute of the "subscribe" element, if the subject's
presence entry changes, an updated "presence" element is
sent as data to the originator using the publish operation
(Section 4.4). Finally, when the amount of time indicated by
the "duration" attribute expires, a terminate operation
(Section 4.5) is sent to the originator.
Note that if the duration is zero-valued, then the subscribe
operation is making a one-time poll of the presence information.
Accordingly, Step 6.3 above does not occur.
Regardless of whether a "publish" or "reply" element is sent to the
originator, the "transID" attribute is identical to the value found
in the "subscribe" element sent by the originator.
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4.3 The Watch Operation
When an application wants to (periodically) receive notices about
endpoints that are subscribed to receive presence information, it
sends a "watch" element to the service.
The "watch" element has a "publisher" attribute, a "duration"
attribute, a "transID" attribute, and no content:
o the "publisher" attribute specifies the endpoint associated with
the presence entry;
o the "transID" attribute specifies the transaction-identifier
associated with this operation; and,
o the "duration" attribute specifies the maximum number of seconds
for which the originator is interested in watching subscribers.
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When the service receives a "watch" element, we refer to the
"publisher" attribute of that element as the "subject", and the
service performs these steps:
1. If the subject is outside of this administrative domain, a
"reply" element having code 553 is sent as data to the
originator.
2. If the subject does not refer to a valid endpoint, a "reply"
element having code 550 is sent as data to the originator.
3. If the subject's access entry does not contain a
"presence:watch" token for the originator, a "reply" element
having code 537 is sent as data to the originator.
4. If the originator already has an in-progress watch operation for
the subject, then the previous watch operation is silently
terminated, and processing continues.
5. If the "transID" attribute refers to an in-progress subscribe or
watch operation for the originator, a "reply" element having
code 555 is sent as data to the originator.
6. Otherwise:
1. A "reply" element having code 250 is sent as data to the
originator.
2. For each endpoint currently subscribing to the subject's
presence information, a "notify" element is immediately sent
as data to the originator (c.f., Section 4.6). Finally, when
the amount of time indicated by the "duration" attribute
expires, a terminate operation (Section 4.5) is sent to the
originator.
3. For up to the amount of time indicated by the "duration"
attribute of the "watch" element, whenever a subscribe
operation succeeds, a "notify" element is sent as data to
the originator. Finally, when the amount of time indicated
by the "duration" attribute expires, the a terminate
operation (Section 4.5) is sent to the originator.
Note that if the duration is zero-valued, then the watch
operation is making a one-time poll of the presence information.
Accordingly, Step 6.3 above does not occur.
Regardless of whether a "notify" or "reply" element is sent to the
originator, the "transID" attribute is identical to the value found
in the "presence" element sent by the originator.
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4.4 The Publish Operation
When an application wants to modify the presence entry associated
with an endpoint, it sends a "publish" element to the service. In
addition, the service sends a "publish" element to endpoints that
have subscribed to see presence information (c.f., Section 4.2).
The "publish" element has a "publisher" attribute, a "transID"
attribute, and contains a "presence" element:
o the "publisher" attribute specifies the endpoint to be associated
with the presence entry;
o the "transID" attribute specifies the transaction-identifier
associated with this operation;
o the "timeStamp" attribute specifies the current date and time;
and,
o the "presence" element contains the desired presence entry for
the endpoint.
When the service sends a "publish" element, the "transID" attribute
specifies the transaction-identifier associated with the subscribe
operation that caused this "publish" element to be sent, and the
"timeStamp" attribute is the service's notion of the current date
and time. No reply is sent by the receiving endpoint.
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When the service receives a "publish" element, we refer to the
"publisher" attribute of that element as the "subject", and the
service performs these steps:
1. If the "publisher" attribute of the "publish" element doesn't
match the "publisher" attribute of the "presence" element
contained in the "publish" element, a "reply" element having
code 503 is sent as data to the originator.
2. If the subject is outside of this administrative domain, a
"reply" element having code 553 is sent as data to the
originator.
3. If the subject does not refer to a valid endpoint, a "reply"
element having code 550 is sent as data to the originator.
4. If the subject's access entry does not contain a
"presence:publish" token for the originator, a "reply" element
having code 537 is sent as data to the originator.
5. If the "lastUpdate" attribute of the "publish" element is not
semantically identical to the last update time of the subject's
presence entry, a "reply" element having code 555 is sent as
data to the originator. (This allows a simple mechanism for
atomic updates.)
6. Otherwise:
1. The subject's presence entry is updated from the "publish"
element.
2. The last update time of the presence entry is set to the
current time.
3. A "reply" element having code 250 is sent as data to the
originator.
When sending the "reply" element, the "transID" attribute is
identical to the value found in the "publish" element sent by the
originator.
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4.5 The Terminate Operation
When an application no longer wishes to subscribe to presence
information or to watch endpoints that are subscribed to receive
presence information, it sends a "terminate" element to the service;
similarly, when the service no longer considers an application to be
subscribing or watching, a "terminate" element is sent to the
application.
The "terminate" element contains only a "transID" attribute that
specifies the transaction-identifier associated an in-progress
subscribe or watch operation. Section 9.1 of [1] defines the syntax
for the "terminate" element.
When the service receives a "terminate" element, it performs these
steps:
1. If the transaction-identifier does not refer to a previous
publish or watch operation for the originator, an "error"
element having code 550 is returned.
2. Otherwise, the previous publish or watch operation for the
originator is terminated, and a "reply" element having code 250
is sent as data to the originator.
Note that following a terminate operation, the originator may
receive further presence or watcher updates. Although the service
will send no further updates after processing a terminate operation
and sending the reply operation, earlier updates may be in transit.
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4.6 The Notify Operation
The service sends a "notify" element to endpoints that are watching
other endpoints subscribed to presence information (c.f., Section
4.3).
The "notify" element has a "subscriber" attribute, a "transID"
attribute, and no content:
o the "subscriber" attribute specifies the endpoint that is
subscribed to presence information; and,
o the "transID" attribute specifies the transaction-identifier
associated with the watch operation that caused this "notify"
element to be sent. No reply is sent by the receiving endpoint.
4.7 The Reply Operation
While processing operations, the service may respond with a "reply"
element. Consult Sections 10.2 and 6.1.2 of [1], respectively, for
the syntax and semantics of the reply operation.
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5. Registration: The Presence Service
Well-Known Endpoint: apex=presence
Syntax of Messages Exchanged: c.f., Section 6
Sequence of Messages Exchanged: c.f., Section 4
Access Control Tokens: presence:subscribe, presence:watch,
presence:publish
Contact Information: c.f., the "Authors' Addresses" section of this
memo
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6. The Presence Service DTD
<!--
DTD for the APEX presence service, as of 2000-12-12
Refer to this DTD as:
<!ENTITY % APEXPRESENCE PUBLIC "-//Blocks//DTD APEX PRESENCE//EN"
"http://xml.resource.org/profiles/APEX/apex-presence.dtd">
%APEXPRESENCE;
-->
<!ENTITY % APEXCORE PUBLIC "-//Blocks//DTD APEX CORE//EN"
"http://xml.resource.org/profiles/APEX/apex-core.dtd">
%APEXCORE;
<!--
Synopsis of the APEX presence service
service WKE: apex=presence
message exchanges:
consumer initiates service replies
================== ================
subscribe publish or reply
terminate reply
watch reply
publish reply
service initiates consumer replies
================= ================
terminate (nothing)
publish (nothing)
notify (nothing)
access control:
token target
================== ======
presence:subscribe for "publisher" of "subscribe" element
presence:watch for "publisher" of "watch" element
presence:publish for "publisher" of "publish" element
-->
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<!ELEMENT subscribe EMPTY>
<!ATTLIST subscribe
publisher %ENDPOINT; #REQUIRED
transID %UNIQID; #REQUIRED
duration %SECONDS; #REQUIRED>
<!ELEMENT watch EMPTY>
<!ATTLIST watch
publisher %ENDPOINT; #REQUIRED
transID %UNIQID; #REQUIRED
duration %SECONDS; #REQUIRED>
<!-- publisher attributes must match in publish and presence -->
<!ELEMENT publish (presence)>
<!ATTLIST publish
publisher %ENDPOINT; #REQUIRED
transID %UNIQID; #REQUIRED
timeStamp %TIMESTAMP; #REQUIRED>
<!ELEMENT notify EMPTY>
<!ATTLIST notify
subscriber %ENDPOINT; #REQUIRED
transID %UNIQID; #REQUIRED>
<!--
presence entries
-->
<!ELEMENT presence (tuple+)>
<!ATTLIST presence
publisher %ENDPOINT; #REQUIRED
lastUpdate %TIMESTAMP; #REQUIRED
publisherInfo
%URI; "">
<!ELEMENT tuple (capability*)>
<!ATTLIST tuple
destination %URI; #REQUIRED
availableUntil
%TIMESTAMP; #REQUIRED
tupleInfo %URI; "">
<!-- e.g., baseline='rfc2533' -->
<!ELEMENT capability (#PCDATA)>
<!ATTLIST capability
baseline NMTOKEN #REQUIRED>
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References
[1] Rose, M.T., Klyne, G. and D.H. Crocker, "The Application
Exchange Framework", draft-mrose-apex-core-00 (work in
progress), December 2000.
[2] Rose, M.T., "The Blocks Extensible Exchange Protocol
Framework", draft-ietf-beep-framework-09 (work in progress),
December 2000.
[3] Rose, M.T., Klyne, G. and D.H. Crocker, "The APEX Access
Service", draft-mrose-apex-access-00 (work in progress),
December 2000.
Authors' Addresses
Marshall T. Rose
Invisible Worlds, Inc.
1179 North McDowell Boulevard
Petaluma, CA 94954-6559
US
Phone: +1 707 789 3700
EMail: mrose@invisible.net
URI: http://invisible.net/
Graham Klyne
Content Technologies Limited
1220 Parkview
Arlington Business Park
Theale, Reading RG7 4SA
UK
Phone: +44 118 930 1300
EMail: gk@acm.org
David H. Crocker
Brandenburg Consulting
675 Spruce Drive
Sunnyvale, CA 94086
US
Phone: +1 408 246 8253
EMail: dcrocker@brandenburg.com
URI: http://www.brandenburg.com/
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Appendix A. Changes from IMXP
o s/IMXP/APEX/g
o Indicate that APEX services are co-resident with each APEX relay.
o Change data's originator from an attribute to an element.
o CPIM mapping moved to another document.
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