IMS-to-IMS TCP/IP connections

TCP/IP connections between two IMS systems are defined by IMS Connect configuration statements and other IMS system definition macros or PROCLIB members that are required by the IMS communications component that uses the TCP/IP connection.

Each defined connection between two IMS Connect instances supports sending primary communications messages only one way. To establish a TCP/IP connection from the remote IMS system back to the local IMS system, a separate TCP/IP connection must be defined from the remote IMS system back to the local IMS system.

A complete connection between two IMS systems has three sections:

  • The connection between the sending IMS system and the sending IMS Connect instance. This section is not a TCP/IP connection, but rather a communications method managed by either the Structured Call Interface (SCI) of an IMSplex or the z/OS® cross-system coupling facility (XCF). IMS Multiple Systems Coupling (MSC) communications uses SCI. IMS Open Transaction Manager Access (OTMA) communications uses XCF.
  • The connection between the sending and receiving IMS Connect instances. This section is a TCP/IP connection.
  • The connection between the receiving IMS Connect instance and the receiving IMS system. This section is managed by either SCI or XCF.

Depending on whether the TCP/IP connection is used for MSC or OTMA communications, the steps for defining the connection differ.

The following figure shows an example IMS-to-IMS TCP/IP communications configuration.

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.