A IMS Event is the processing defined on a particular message received from IMS. An IMS program sends a message to communicate that a specific event occurs, for example, when an inventory level crosses a threshold. In the most common use case, an EBCDIC COBOL Copybook formatted record is received, converted to an XML document, and delivered to a queue or program.

All processing details for a message are configured under a channel, which include:

• Communications parameters with IMS, for example, TCP port.
• Message layouts defined in COBOL Copybooks.
• Assigned ports to which the message is routed as an XML document.

An IMS Event can be configured as REQUEST only, in which the Event consumes a message, or REQUEST/RESPONSE, in which the Event consumes a message and returns a reply message.

The following diagrams and sequences illustrate REQUEST and REQUEST/RESPONSE scenarios:

REQUEST

The following sequence outlines how request messages are processed.

1. A message is created by an IMS user program.
2. The message is sent via TCP to a channel (TCP port).
3. The channel receives the message.
4. If the channel is configured to work with Copybook formatted messages, it converts the message to XML.
5. The channel routes the message to one or more destination ports for further processing, for example, to a JMS queue.

REQUEST/RESPONSE

The following sequence outlines how request/response messages are processed.

1. A message is created by an IMS user program.
2. The message is sent via TCP to a channel (TCP port).
3. The channel receives the message.
4. If the channel is configured to work with Copybook formatted messages, it converts the message to XML.
5. The channel routes a message to a destination port for further processing, for example, an HTTP request.
6. The port takes an XML document as input and returns an XML document as output to the channel. For channels configured with COBOL Copybook formatted messages, these documents conform to the XML schemas generated from these Copybooks using iWay Explorer.
7. If the channel is configured to work with Copybook formatted messages, it converts the XML into Copybook format.
8. The channel returns the reply message to the IMS program.