<p><cite>RFC 3920</cite> describes several ways to terminate an XMPP stream, but does not always make a clear statement about which to use. This can lead to faulty implementations. In particular, closing a stream that has not been in use for a while is very often achieved using a connection-timeout error, then closing the socket. This can lead to loss of data. Therefore this document proposes a practice that will avoid such data loss.</p>
<p>Note: The recommendation described herein has been incorporated into <cite>rfc3920bis</cite>.</p>
<p>As shown in the basic "session" example in the Simplified Stream Examples (4.8 of RFC 3920), it is a valid transaction to close the outgoing stream by sending
<p>This will ensure that, should the other entity have transmitted any data, it will arrive and be processed before the TCP connection is terminated.</p>
<p>Special care MUST be taken that under no circumstance further packets may be written to the socket after the stream was closed, until the other side shuts down the socket.</p>
<p>On the outgoing TCP connection, an implementation MAY do a read-only shutdown of the socket, as long as the other side will safely be able to send its stream termination token.</p>
<p>In case the other entity fails to close the stream within a reasonable time frame, the entity that started the handshake is entitled to terminate the TCP connection. Since the stream has already been closed, it is correct not to produce an error condition.</p>
<p>Existing implementations should be updated to use the 'Handshake Stream Shutdown' strategy when shutting down streams that are no longer needed. This strategy is fully backwards-compatible and does not introduce any known communication problems.</p>
