SOAP Gateway server

The SOAP Gateway server acts as the gateway between external web services and IMS applications. It serves as a web service server where IMS applications are enabled as web services. It serves a web service consumer when it forwards IMS application callout requests to external web services.

In all scenarios, the SOAP Gateway server acts as a client to IMS Connect.

SOAP Gateway provides these functions by offering direct SOAP access to existing IMS transactions. SOAP Gateway also enables IMS transactions to request for external web services through the SOAP protocol. SOAP Gateway communicates with IMS through IMS Connect, the TCP/IP gateway for IMS. Messages between IMS Connect and SOAP Gateway can be transmitted in XML format through Secure Sockets Layer (SSL). IMS Connect converts the XML data into bytes and passes the request to the IMS application through IMS Open Transaction Manager Access (OTMA).

IMS OTMA is a transaction-based, connectionless protocol that addresses the problem of connecting a client to a server so that the client can support a large network, or many sessions, while maintaining high performance. IMS Connect is a client to OTMA, and the SOAP Gateway server is a client to IMS Connect.

SOAP Gateway communicates with its client through the HTTP protocol. HTTPS is used for secure communications.

Figure 1. SOAP Gateway system layout and setup
Begin figure description. This diagram shows the protocols and message formats between SOAP Gateway and its clients, and between SOAP Gateway and IMS Connect. End figure description.

SOAP Gateway can be installed on z/OS® in the same or different LPAR as IMS. This setup simplifies the infrastructure and improves the efficiency.

Figure 2. SOAP Gateway system layout and setup on z/OS
Begin figure description. This diagram shows that SOAP Gateway is installed on the same z/OS installation as IMS. End figure description.

You can have a sysplex distributor environment where traffic to SOAP Gateway can be distributed to different installations to help balance the load.

Figure 3. SOAP Gateway system layout and setup on z/OS with a sysplex distributor
Begin figure description. This diagram shows that a sysplex distributor distributes the traffic to different instances of SOAP Gateway installation on z/OS to balance the load. End figure description.

When the SOAP Gateway server handles callout requests from IMS applications to external web services, it becomes a client to the external web application server. Regardless, SOAP Gateway communicates with the external web server using the same protocol, and SOAP Gateway remains a client to IMS Connect.