The capability to reuse existing business functionality via Web Services technology, instead of system rewrite, is attractive in terms of total implementation cost, integration effort, and risks.
Business functionality developed on IBM legacy mainframe platforms can be integrated by exposing the business service (for example, from existing CICS screens, SNA LU 6.2 verbs, and COMMAREA) via SOAP client proxy and XML-RPC technology.
There are a few interoperability approaches to expose the business functionality of the legacy mainframe platform: CICS Transaction Gateway, APPC adapter, EAI adapter for mainframe, Linux 390/z/OS, WebSphere/390, and SOAP proxy on z/OS. Each of these approaches requires additional software to be installed and thus have different architecture impacts. These approaches assume a long- term commitment to using a legacy mainframe.
The alternatives to interoperating with a legacy mainframe assume a stop-gap measure to integrate with the mainframe systems using Web Services technology, while migrating the business functionality to the Open Standards in parallel. The migration can be done using transcode, recompile, rehost, and refront technology.
