Initial published version approved by the XMPP Council.
First draft.
It is common for IM clients to be logged in and 'online' even while the user is not interacting with the application. This + protocol allows the client to indicate to the server when the user is not actively using the client, allowing the server to + optimise traffic to the client accordingly. This can save bandwidth and resources on both the client and server.
+The aim of this specification is to provide a simple and efficient protocol for the client to report its + state to the server. Exactly how the server uses this information is beyond the scope of this document, although + some examples are given.
+Other extensions exist, such as &xep0273;, which also aim to optimise the traffic between the client and server. + A notable difference is that instead of being client-controlled, CSI shifts the responsibility to the server, and + aims to just provide the server with enough information to implement various optimisations itself.
+Juliet has an XMPP client on her phone, which is available to receive messages. However most of the time + Juliet has her phone screen turned off and is not interested in the status of her contacts unless they are + communicating with her.
+ +Juliet's client informs the server when Juliet is not interacting with it. The server uses this information to + suppress or reduce stanzas that are unimportant, such as status updates.
+ +When Juliet returns to her IM client, the client again informs the server, this time to report that it is active + again. The server then disables its traffic optimisations and restores the stream to its normal state.
+When the server knows that the user is not engaging with their client many optimisations become possible. For + example a server could:
+This list is for example only, a server is not required to implement all or any of these, nor is it prevented + from implementing other behaviour not listed here. Regardless of what optimisations a server implements, it SHOULD + provide a way for administrators to configure them, and MAY provide such configuration to users also (e.g., through an + ad-hoc command).
+If the server supports CSI, it advertises it in the stream features after the client has authenticated:
+A stream always begins in 'active' state. If a client wishes to inform the server that it has become inactive, + it sends an <inactive/> element in the 'urn:xmpp:csi:0' namespace:
+As might be anticipated, when the client is active again it sends an <active/> element:
+There is no reply from the server to either of these elements (though they may indirectly cause the server to + send stanzas, e.g., to update presence information when the client becomes active after a period of inactivity).
+As this protocol is for indication only, clients MUST NOT make assumptions about how the server + will use the active/inactive state information.
+ +The server MUST assume all clients to be in the 'active' state until the client indicates otherwise. Also the + CSI active/inactive state is unrelated to the user's presence, the server MUST treat the two independently.
+ +This protocol is intended primarily for clients with human interaction. Due to the open-ended nature of + the possible optimisations implemented by the server, it may not be suitable for non-IM purposes where the + fully standard behaviour of XMPP is required.
+To protect the privacy of users, servers MUST NOT reveal the clients active/inactive state to other + entities on the network.
+This document requires no interaction with &IANA;.
+This document requires no interaction with ®ISTRAR;.
+
+
+
+
+
+
+
+
+
+
+ ]]>
+