Containers used in web services pipelines

A pipeline typically consists of a number of message handler programs and, when the CICS®-supplied SOAP message handlers are used, a number of header processing programs. CICS uses containers to pass information to and from these programs. The programs also use containers to communicate with other programs in the pipeline.

The CICS pipeline links to the message handlers and to the header processing programs by using a channel that has a number of containers. Some containers are optional, others are required by all message handlers, and others are used by some message handlers and not by others.

Before a handler is invoked, some or all of the containers are populated with information that the handler can use to perform its work. The containers returned by the handler determine the subsequent processing, and are passed on to later handlers in the pipeline.

The containers can be categorized in these ways:

Control containers: These containers are essential to the operation of the pipeline. Handlers can use the control containers to modify the sequence in which the handlers are processed. The names of the control containers are defined by CICS, and begin with the characters DFH.
Context containers: These containers contain information about the environment in which the handlers are called. CICS puts information in these containers before it invokes the first message handler, but, in some cases, the handlers are free to change the contents, or to delete the containers. Changes to the context containers do not directly affect the sequence in which the handlers are invoked. The names of the context containers are defined by CICS, and begin with the characters DFH.
Header processing program containers: These containers contain information that is used by header processing programs that are called from the CICS-supplied SOAP message handlers. For information about header processing programs, see Header processing programs. For information about the header processing program interface, see The header processing program interface.
Security containers: These containers contain information that is used by the Trust client interface and the security message handler to process security tokens using a Security Token Service (STS). The names of the security containers are defined by CICS, and begin with the characters DFH.
Generated containers: These containers contain the data from the SOAP message, such as variable arrays and long strings, that is passed to and from the application program for processing. CICS automatically creates these containers during pipeline processing, and the names begin with the characters DFH.
User containers: These containers contain information that one message handler needs to pass to another. The use of user containers is entirely a matter for the message handlers. You can choose your own names for these containers, but you must not use names that start with DFH.