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1.1rc5

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git-svn-id: file:///home/ksmith/gitmigration/svn/xmpp/trunk@4080 4b5297f7-1745-476d-ba37-a9c6900126ab
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Peter Saint-Andre 2010-03-15 17:18:07 +00:00
parent 3a204821c2
commit 4331cb54a1
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xep-0184.xml
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@ -29,8 +29,8 @@
&stpeter;
&hildjj;
<revision>
<version>1.1rc4</version>
<date>in progress, last updated 2010-03-12</date>
<version>1.1rc5</version>
<date>in progress, last updated 2010-03-15</date>
<initials>psa</initials>
<remark><p>Relaxed the business rules to allow inclusion of receipt requests even to the bare JID and even if the sender does not yet know whether the intended recipient supports this protocol; clarified the level of reliability that this protocol does and does not provide; provided explicit recommendations about when and when not to request receipts; removed text about XEP-0155 negotiation.</p></remark>
</revision>
@ -79,7 +79,7 @@
</header>
<section1 topic='Introduction' anchor='intro'>
<p>While &xep0079; provides message acknowledgements at the server level, it does not extend that model all the way to the client. However, sometimes client-level acknowledgements are needed, for example to provide "receipts". This document defines a mechanism for XMPP message receipts, which are functionally equivalent to the "delivered" or "displayed" event in &xep0022;, which this specification in part obsoletes. <note>This specification does not distinguish between delivery and presentation, as was done in the message events protocol, in part because no existing clients make the distinction.</note></p>
<p>While &xep0079; provides message acknowledgements at the server level, it does not extend that model all the way to the client. <note>Naturally, message receipts can be combined with the rules specified in <cite>Advanced Message Processing</cite> for more complete reporting.</note> However, sometimes client-level acknowledgements are needed, for example to provide "receipts". This document defines a mechanism for XMPP message receipts, which are functionally equivalent to the "delivered" or "displayed" event in &xep0022;, which this specification in part obsoletes. <note>This specification does not distinguish between delivery and presentation, as was done in the message events protocol, in part because no existing clients make the distinction.</note></p>
<p>Note: This extension is functionally equivalent to an <cite>Advanced Message Processing</cite> rule of "receipt" but uses a dedicated namespace to simplify processing by end user clients and intermediate routers.</p>
</section1>
@ -91,7 +91,7 @@
</ol>
</section1>
<section1 topic='Reliability' anchor='reliability'>
<section1 topic='What This Protocol Provides' anchor='what'>
<p>This document defines a protocol that enables a sender to ask the recipient to return a receipt for a message. Although the return of a message receipt lets the sender know that the message has been delivered, there are many reasons why the sender might not receive a receipt immediately or at all, including but not limited to the following:</p>
<ul>
<li>The sender addressed the message to the recipient's bare JID &LOCALBARE; and therefore does not know if the recipient even supports message receipts.</li>
@ -100,9 +100,24 @@
<li>The intended resource supports message receipts but the recipient's server delivers the message to another resource that does not support message receipts.</li>
<li>The recipient's client receives the message but experiences a malfunction before generating a receipt.</li>
<li>The recipient returns a receipt but the receipt is lost on the way back from the recipient to the sender (e.g., because of connectivity issues or software failures at any hop).</li>
<li>The recipient simply does not wish to return a receipt for the sent message.</li>
</ul>
<p>As a result, this document does not define a protocol for complete reliability or guaranteed delivery, and those who implement and deploy this protocol need to be aware of its limitations, as described throughout this specification.</p>
<p>Note: Message receipts can be combined with the rules specified in <cite>Advanced Message Processing</cite> (e.g., the deliver rule) for more complete reporting.</p>
<p>Because of these significant limitations, this protocol does not provide complete or even partial reliability or guaranteed delivery. Therefore, the sender SHOULD NOT impute any meaning to the lack of a receipt unless it has established with the recipient that receipt requests will be honored; however, methods for doing so are out of scope for this specification and it is NOT RECOMMENDED to take any particular action (such as resending a message) without such methods.</p>
</section1>
<section1 topic='When to Request Receipts' anchor='when'>
<p>A sender <em>could</em> request receipts on any non-error message (chat, groupchat, headline, or normal) no matter if the recipient's address is a bare JID &LOCALBARE; or a full JID &LOCALFULL;. Whether it is <em>appropriate</em> or <em>advisable</em> to do so it another question. This section provides recommendations about when and when not to request receipts, and what results to expect in each scenario.</p>
<section2 topic='Bare JID' anchor='when-bare'>
<p>If the sender knows only the recipient's bare JID, it cannot cannot determine (via disco or caps) whether the intended recipient supports message receipts. In this case, the sender MAY request a receipt when sending a message of type "chat", "headline", or "normal" to the recipient's bare JID. However, the sender MUST NOT depend on receiving a receipt.</p>
</section2>
<section2 topic='Full JID' anchor='when-full'>
<p>If the sender knows a full JID for the recipient (e.g., via presence), it SHOULD attempt to determine (via disco or caps) whether the client at that full JID supports message receipts before attempting to request receipts.</p>
<p>If the sender determines that the recipient's client supports message receipts then it MAY request a receipt when sending a message of type "chat", "headline", or "normal" to that full JID. If the sender has requested a receipt, it MAY depend on receiving a receipt.</p>
<p>If the sender determines that the recipient's client does not support message receipts then it SHOULD NOT request a receipt when sending a message to that full JID.</p>
</section2>
<section2 topic='Groupchat' anchor='when-groupchat'>
<p>It is NOT RECOMMENDED to request a receipt when sending a message of type "groupchat" in a &xep0045; room because the logic for determining when a message is truly "received" by all of the room occupants is complex and because the sender would receive one receipt from each occupant of the room, thus significantly increasing the number of messages sent through the room.</p>
</section2>
</section1>
<section1 topic='Determining Support' anchor='disco'>
@ -128,21 +143,6 @@
<p>Support can also be determined via &xep0115; a.k.a. "caps".</p>
</section1>
<section1 topic='When to Request Receipts' anchor='when'>
<p>A sender <em>could</em> request receipts on any non-error message (chat, groupchat, headline, or normal) no matter if the recipient's address is a bare JID &LOCALBARE; or a full JID &LOCALFULL;. Whether it is <em>appropriate</em> or <em>advisable</em> to do so it another question. This section provides recommendations about when and when not to request receipts, and what results to expect in each scenario.</p>
<section2 topic='Bare JID' anchor='when-bare'>
<p>If the sender knows only the recipient's bare JID, it cannot cannot determine (via disco or caps) whether the intended recipient supports message receipts. In this case, the sender MAY request a receipt when sending a message of type "chat", "headline", or "normal" to the recipient's bare JID. However, the sender MUST NOT depend on receiving a receipt and MUST NOT resend the message if it does not receive a receipt.</p>
</section2>
<section2 topic='Full JID' anchor='when-full'>
<p>If the sender knows a full JID for the recipient (e.g., via presence), it SHOULD attempt to determine (via disco or caps) whether the client at that full JID supports message receipts before attempting to request receipts.</p>
<p>If the sender determines that the recipient's client supports message receipts then it MAY request a receipt when sending a message of type "chat", "headline", or "normal" to that full JID. If the sender has requested a receipt, it MAY depend on receiving a receipt and MAY resend the message if it does not receive a receipt within some configurable timeout period (however, resend logic is out of scope for this specification).</p>
<p>If the sender determines that the recipient's client does not support message receipts then it SHOULD NOT request a receipt when sending a message to that full JID and MUST NOT resend the message if it does not receive a receipt.</p>
</section2>
<section2 topic='Groupchat' anchor='when-groupchat'>
<p>It is NOT RECOMMENDED to request a receipt when sending a message of type "groupchat" in a &xep0045; room because the logic for determining when a message is truly "received" by all of the room occupants is complex and because the sender would receive one receipt from each occupant of the room, thus significantly increasing the number of messages sent through the room.</p>
</section2>
</section1>
<section1 topic='Protocol Format' anchor='format'>
<p>In order to make it possible for senders to request and for recipients to generate message receipts, we define a dedicated protocol extension qualified by the 'urn:xmpp:receipts' namespace.</p>
<p>There are two allowable elements in this namespace:</p>
@ -222,4 +222,5 @@
<section1 topic='Acknowledgements' anchor='ack'>
<p>Thanks to Joe Kemp and Kevin Smith for their input.</p>
</section1>
</xep>