Start here to find out how CICS supports Web services.
CICS and Web Services
What the world wide web did for interactions between programs and
end users, Web services can do for program-to-program interactions. Web services
make it possible for applications to be integrated more rapidly, easily, and
cheaply than ever before.
The Web services architecture
The Web services architecture is based upon interactions between
three components: a service provider, a service requester, and an optional
service registry.
What is SOAP?
SOAP is a protocol for the exchange of information in a distributed
environment. SOAP messages are encoded as XML documents, and can be exchanged
using a variety of underlying protocols.
How CICS supports Web services
CICS® supports
two different approaches to deploying your CICS applications in a Web services environment.
One approach enables rapid deployment, with the least amount of programming
effort; the other approach gives you complete flexibility and control over
your Web service applications, using code that you write to suit your particular
needs. Both approaches are underpinned by an infrastructure consisting of
one or more pipelines and message handler programs
which operate on Web service requests and responses.
Getting started with Web services
There are several ways to get started with Web services in CICS.
Which is most appropriate for you will depend upon how much you already know
about the subject, and upon how well advanced your plans are for using Web
services.
The CICS Web services assistant
The CICS Web
services assistant is a set of batch utilities which can help you to transform
existing CICS applications
into Web services and to enable CICS applications to use Web services provided
by external providers. The assistant supports rapid deployment of CICS applications
for use in service providers and service requesters, with the minimum of programming
effort.
Interfacing with service provider and requester applications
You must code your service provider and service requester
applications (or wrapper programs) to interact with the Web services support
in CICS.
How you do this depends upon whether you are developing a service provider
application or a service requester, and whether you are using the CICS Web services
assistant to deploy your application.
The pipeline configuration file
The configuration of a pipeline used to handle a Web service request
is specified in an XML document, known as a pipeline configuration file.
Message handlers
A message handler is a CICS program which is used to process a
Web service request during input, and to process the response during output.
Message handlers use channels and containers to interact with one another,
and with the system.
The SOAP message handlers
The SOAP message handlers are CICS-provided message handlers that
you can include in your pipeline to process SOAP 1.1 and SOAP 1.2 messages.
You can use the SOAP message handlers in a service requester or in a service
provider pipeline.
Containers used in the pipeline
A pipeline typically consists of a number of message handler programs
and, when the CICS-supplied SOAP message handlers are used, a number of header
processing programs. CICS uses containers to pass information to and from
these programs. The programs also use containers to communicate with other
programs in the pipeline.
Support for Web Services transactions
The Web Services Atomic Transaction (or WS-AtomicTransaction) specification
and the Web Services Coordination (or WS-Coordination) specification define
protocols for short term transactions that enable transaction processing systems
to interoperate in a Web services environment. Transactions that use WS-AtomicTransaction
have the ACID properties of atomicity, consistency, isolation,
and durability.
Support for Web Services Security
The Web Services Security (WSS): SOAP Message Security 1.0 specification
describes the use of security tokens and digital signatures to
protect and authenticate SOAP messages.
Diagnosing problems
The problems that you might get when implementing Web services
in CICS can occur during the deployment process or at run time, when CICS
is transforming SOAP messages.
The CICS catalog manager example application
The CICS catalog
example application is a working COBOL application that is designed
to illustrate best practice when connecting CICS applications to external clients and
servers.