This topic describes the ability of the Enterprise Service
Tools perspective to enable IMS™ multi-segment
Message Processing Programs (MPPs) as Web
services in the bottom-up "Create New Service Interface" development
scenario.
With certain restrictions, the language structure selection panels
in the Web service wizard allow multiple language structures. As part
of the page "IMS Message Layouts",
two selection tabs are provided; the Request Message Layout tab and
the Response Message Layout tab.
Use the "Request Language Structures" and "Response Language Structures"
tabs on the "Language Structures" page to select the structures that
describe the request and response interfaces to the IMS MPP. When language structures are selected
on the language structure tabs, they are entered into corresponding
tables on the "IMS Message Layouts"
page.
After selecting the language structures, use the tabs on the "IMS Message Layouts" page to specify
the layout of the request and response messages in detail. Indicate
the order and count of each language structure in their respective
messages by using the tables on the "Request Message Layout" and "Response
Message Layout" tabs. The layouts specified in these tables indicate
how the XML and binary messages are structured.
Limitations and Error Conditions
In general,
multiple language structure selection and multi-segment support is
supported only for IMS Enterprise
Suite SOAP Gateway and IMS MPPs
written in COBOL.
The following limitations apply when specifying
the IMS message layouts:
- While a language structure can occur more than once, the occurrences
MUST be consecutive; they cannot be interleaved with occurrences of
other language structures.
- At most one language structure can occur a variable number of
times (variable-count) and may only be followed by a language structure
with a minimum and maximum count of one.
- The total maximum size of the message layout, when represented
in either XML or binary format cannot exceed 32MB when Enterprise
COBOL V3R4 or later is used, or 16MB when Enterprise COBOL V3R3 or
earlier is used.
The following limitations apply when selecting multiple
language structures:
- Each language structure must begin with two 2-byte fields (LL
and ZZ per IMS).
- Each language structure cannot exceed 32767 bytes (maximum size
of an IMS message segment).
- At most 256 language structures can be selected for each of the
request and response.
- Inter-language structure dependencies are not supported; for example,
OCCURS DEPENDING ON (ODO) subjects in selected language structures
cannot specify an ODO object declared outside of the structure.