In this chapter we discuss the reasons why a large CICS site would consider using CICS Web Services as an interface to their heritage application systems. We also give a brief overview of CICS Web Services and introduce the application we develop in this book. Why we wrote this book
This book is intended to be of most use to the CICS Application Developer/ Architect who needs to see a practical demonstration of how to develop applications that take advantage of CICS Web services facilities. This book can be viewed as a follow-on from the IBM Redbooks publication Application Development for CICS Web Services, SG24-7126-00, with the addition of using modern tooling techniques. Because we are creating a new application, we follow the bottom-up approach described in Application Development for CICS Web Services, SG24-7126-00. Although not a requirement, we highly recommend that you review that publication for a much deeper discussion of CICS Web services development topics and alternative approaches.
The primary purpose of this book is to demonstrate that well structured CICS Web Services are easy to develop using the CICS Web services assistant. We also take a look at modern tooling such as WebSphere Developer for zSeries (WD/z) which the traditional mainframe developer may not have seen before. As traditional developers we found the Eclipse-based interface to the mainframe a new and exciting way to both interact and use facilities on the mainframe.
In the Redbooks publication Application Development for CICS Web Services, SG24-7126-00 we showed how to expose a CICS application, namely the CICS Catalog Manager sample application. We now take this process one step further by developing a CICS application from the ground up that will be CICS Web Services enabled. We initially develop this application that runs in CICS using standard BMS (3270) panels as an initial front-end. As the application and display logic are separate, we are well placed to use the business functions as CICS Web Services creating the WSDL interface using the CICS Web services assistant.
The application we develop is a simple but new concept. It uses the publish / subscribe functionality of WebSphere Message Broker (WMB) and therefore WMQ as a backbone. External subscribers, on receipt of a notification will invoke a sequence of CICS Web Services. This application is described in “The Change of Address application” and the technical implementation details are fully described in “Development of the Change of Address CICS application”.
Above all else, we want to demonstrate that creating Web services from new and existing CICS applications using the CICS Web services assistant is easy and worthwhile.
Of course, one of the chief concerns when exposing CICS functions as Web services is security. This is a topic that is covered at length in another Redbooks publication Securing Access to CICS Within an SOA, SG24-5756-01.