Web services in CICS provides an interpretive engine that converts XML data to and from language structures. The interpretive engine does not support all the data constructs and types in the COBOL language, making it necessary for the CICS Web services developer to write additional code or a wrapper program to process unsupported types. The behavior of the interpretive engine is not configurable, whereas a user may have very specific needs in processing SOAP messages.
A standard interface between CICS combined with a user supplied program that provides XML conversion to and from language structures is called the "vendor interface". The vendor interface allows users to have pluggable XML conversion. XML converters generated by Enterprise Service Tools have broader support for data constructs and types. We recommend using these XML converters with the vendor interface. For improved debugging, CICS Transaction Server Version 3.1 treats the compiled converters as user code, which allows debugging should a failure occur. The interpretive engine cannot be debugged or changed by the user.
New in CICS Transaction Server Version 3.1, is a batch job called DFHLS2WS (Language Structure to WSDL) which is equivalent to the bottom-up approach of Web services development (see Web service development scenarios: Single-service projects). Enterprise Service Tools, used in combination with the vendor interface as a replacement for DFHLS2WS, provides expanded functionality to the end user. This combination helps a user to enable Web service interface with a COBOL data type that is not supported by the CICS interpretive conversion engine, generally without requiring the user to write any additional wrapper conversion program.