Structure of messages from Q Capture to a user application
A Q Capture program sends both data messages and informational messages to a user application. The data messages convey changes to a source table that is part of a publication. The informational messages either confirm a user application's request with a control message, report on the status of the Q Capture program, or report publication errors.
- List of messages from Q Capture to a user application
The Q Capture program sends two types of messages to a user application: data messages and control messages. - msg: Root element for XML messages from Q Capture to a user application
The msg element is the root element for all data messages and informational messages from the Q Capture program to a user application. - Transaction message
A transaction message contains one or more insert, update, or delete row operations on the source table. The transaction message also contains information about the time that the transaction was committed at the source database, and a time-based log sequence number. - Row operation message
A row operation message contains one insert, update, or delete operation from the source table. In a row operation message, the message element (msg) contains a row operation element (rowOp). - Large object (LOB) message
A large object (LOB) message transmits some or all of the data from a column in the source table that contains a large object value: BLOB (binary large object), CLOB (character large object), or DBCLOB (double-byte character large object). - Subscription deactivated message
A subscription deactivated message confirms that the Q Capture program received the deactivate subscription message from the user application. - Load done received message
The load done received message acknowledges that the Q Capture program received the load done message from the user application. The load done message signifies that a target table is loaded. - Error report message
The Q Capture program sends an error report message when it cannot perform the request of a user application that was made through a control message. - Heartbeat message
A heartbeat message tells the user application that a Q Capture program is still running. The Q Capture program puts these messages on active send queues each time the heartbeat interval for the publishing queue map that contains the send queue is reached if there are no messages to put on the queue. If the Q Capture program reaches the end of the log before this interval occurs, it sends a heartbeat message with no information about the last commit time. - Subscription schema message (subSchema)
The Q Capture program sends a subscription schema message to acknowledge that it activated or reinitialized a publication. The message conveys details about the publication, including the names of the source table and send queue, data-sending options, and information about the load phase. The subscription schema message is sent in response to an activate subscription message, a reinit command, or a REINIT_SUB signal. - Add column message
An add column message tells the user application that a Q Capture program added a column to an existing publication. This message is sent in response to a user or user application inserting an ADDCOL signal into the IBMQREP_SIGNAL table.