Diagnosing IMS problems
This topic describes how to diagnose IMS™ problems, and contains the following subtopics:
The IMS TCP/IP Services socket interface allows TCP/IP clients to access IMS using a TCP/IP network. This access is fully described in z/OS Communications Server: IP IMS Sockets Guide. A sockets program-to-program connection is established between a client (TCP/IP socket) program and a server (IMS application) program. TCP/IP and the Listener are agents in the connection establishment. The components of the IMS TCP/IP socket interface system are shown in Figure 1.
Figure 1. Components of the IMS TCP/IP services socket interface system
The following list is a brief description of the component
interaction and data flow that occurs when a client program requests
an IMS transaction.
- 1
- The client program starts and sends the transaction request message (TRM) to the Listener port.
- 2
- The Listener reads the TRM and accepts the socket connection between the client program and the Listener from TCP/IP.
- 3
- The Listener validates the TRM, prepares to give the socket connection to the IMS transaction, builds the transaction initiation message (TIM) containing the socket connection information, and sends the TIM to the IMS transaction manager message queue. For implicit IMS transactions, the Listener also reads the input data from the client program and sends it to the message queue.
- 4
- The IMS transaction manager schedules the requested transaction.
- 5
- IMS Transaction. This can
be one of the following:
- Implicit
- The IMS assist module receives the TIM on behalf of the implicit IMS transaction and takes the socket connection from the Listener. The input data is read and the IMS transaction performs the required database access. The IMS assist module, on behalf of the implicit IMS transaction, writes the output data to the client program, through the socket connection, followed by the commit status message (CSM). The socket connection then closes.
- Explicit
- The explicit IMS transaction receives the TIM and takes the socket connection from the Listener. Input and output data is read and written as defined by the protocol, and the required database access is performed. The explicit IMS transaction writes the CSM to the client program and closes the socket connection.
The IMS transaction and the client program terminate.