This section covers general issues in Message Queue 4.1. Some of these were introduced with previous Message Queue versions.
When a JMS client using the HTTP transport terminates abruptly (for example, using Ctrl-C) the broker takes approximately one minute before releasing the client connection and all the associated resources.
If another instance of the client is started within the one minute period and if it tries to use the same ClientID, durable subscription, or queue, it might receive a “Client ID is already in use” exception. This is not a real problem; it is just the side effect of the termination process described above. If the client is started after a delay of approximately one minute, everything should work fine.
SOAP clients. Previously the SAAJ 1.2 implementation jar used to refer to mail.jar and mail.jar did not need to be in CLASSPATH. In SAAJ 1.3 this reference was removed; thus, Message Queue clients must put mail.jar explicitly in CLASSPATH.