Feedback

Each request message must have type MQMT_REQUEST, and has to specify valid ReplyToQMgr and ReplyToQ fields in its descriptor. Otherwise WindowsEnabler/MQSeries is not able to return any information back to the requester. In addition, we require that the request message specifies MQRO_PAN and MQFB_NAN in the Report field of the request message descriptor, because we need the requester to be prepared to receive positive/negative action notifications (see below). If WindowsEnabler/MQSeries receives a message that does not conform to this, it will reject the message and move it to the dead-letter queue of the queue manager. To avoid storing large messages in the request queue messages larger than 1 KBytes are truncated. If no dead-letter queue has been specified each invalid request will be discarded.

If a request returns information (other than progress messages), it will be returned over the reply queue as a sequence of one or more message of type MQMT_REPLY and format MQFMT_STRING. At the moment, this is only the case for the internal *dir command, which returns a directory listing. All other commands do not return information (but they do return progress messages, see the following paragraphs).

Apart from result messages, WindowsEnabler/MQSeries will return progress messages. These messages contain information about the state of the request, and in particular whether are request was successful or not. Progress messages have type MQMT_REPORT, format MQFMT_STRING and one of the following feedback codes.

• MQFB_NONE. These messages contain a character string with progress information (and warnings).
• MQFB_PAN. A positive action notification. These notifications indicate that the request was successfully handled. The moment that this message will be returned depends on the WAIT parameter in the request. After a positive action notification has been sent, no more messages will be returned for this particular request. Positive action notifications contain a character string with the result code of the request (see the reference section for the format of this string).
• MQFB_NAN. A negative action notification. These notifications indicate that WindowsEnabler failed to handle the request. The moment that this message will be returned depends on the WAIT parameter in the request. After a negative action notification has been sent, no more messages will be returned for this particular request. Negative action notifications contain a character string that explains what went wrong (see the reference section for the format of this string).

Apart from these WindowsEnabler-related reports the options in the Report field of the request message descriptor may be used to control the following (see the MQSeries manuals):

• Progress messages generated by MQSeries. In particular one can ask MQSeries to send a MQFB_COD (Confirm On Delivery) report, which indicates that MQSeries has handed over the request to WindowsEnabler. This signals that WindowsEnabler is about to handle the request.
• The contents of MsgId and CorrelId fields in progress messages. These identifiers can be used to relate progress messages to the original request. This can be used to distinguish progress messages from previous requests from those of the current request. This may be needed if timeouts are used on requests.

Note

If WindowsEnabler shuts down, it will retrieve all outstanding requests from the request queue and return a negative action notification for each.