IMS Connect support for IMS-to-IMS TCP/IP communications

IMS Connect manages the TCP/IP connections and protocols for IMS systems that communicate with each other across a TCP/IP network.

An IMS-to-IMS TCP/IP connection typically links two IMS systems that are installed at different locations. Each IMS system communicates with an IMS Connect instance at the same location. The TCP/IP connection that the two IMS system use to communicate with each other is established by the IMS Connect instances at each location.

The following figure illustrates possible configurations for IMS-to-IMS TCP/IP connections.

Figure 1. Example configuration for IMS-to-IMS TCP/IP communications
begin graphic description. IMS1 (shown on the left) has two boxes within it: OTMA and MSC. Next to IMS1 (on the right) is IMS Connect 1. IMS1 sends OTMA and MSC messages (using XCF and SCI) to IMS Connect 1, which in turns sends the messages to IMS Connect 2 (using TCP/IP). IMS Connect 2 then sends the OTMA and MSC messages (using XCF and SCI) to the OTMA and MSC boxes within IMS2 on the far right. The MSC instance in IMS2 sends its responses back to IMS1 MSC through the IMS Connect instances. end graphic description.

The RMTIMSCON statement in the IMS Connect configuration member in the IMS.PROCLIB data set defines the TCP/IP connection from one IMS Connect instance to the other. Depending on which IMS communications component uses the TCP/IP connection, additional configuration statements, descriptors, or system definition macros are required to complete the communications path between the two IMS systems.

Each defined TCP/IP connection provides a one-way path for messages from one IMS system to flow to the other. For messages to flow back in the other direction, a second TCP/IP connection must be defined in the reverse direction. Acknowledgment messages (ACKs or NAKs) are the exception to this rule.

Optionally, IMS Connect can secure the IMS-to-IMS TCP/IP connections by using RACF® PassTickets. When PassTicket security is enabled, the sending IMS Connect instance generates a PassTicket and the receiving IMS Connect instance verifies the PassTicket with RACF. After the PassTicket is verified, the receiving IMS Connect classifies the connection as coming from a trusted user. As long as the connection persists, no further security checking is performed.

The IMS Connect user message exit routines, such as HWSJAVA0, HWSSMPL0, or HWSSMPL1, are not used for IMS-to-IMS TCP/IP communications.

IMS-to-IMS TCP/IP communications are supported by the following IMS Connect command formats:

  • WTOR
  • z/OS® MODIFY
  • IMS type-2

The IMS Connect Event Recorder exit routine (HWSTECL0) records events that are specific to IMS-to-IMS TCP/IP communications.

The IMS communications components that use IMS-to-IMS TCP/IP communications include Multiple Systems Coupling (MSC) and Open Transaction Manager Access (OTMA).