JSimpleCalculator: Java application that provides a new front-end to the SMPLCALC COBOL application.
SmplCalcInterfaceHelper: helper class for building the interface COBOL data structure, can be generated by a commercial product such as RAD.
Java to COBOL Marshaller: class library that implements marshalling of Java data types to/from COBOL data types, likely comes with a commercial J2EE server such as WebSphere Application Server (WAS).
Figure 9.3. Example JCA implementation for accessing a legacy application.
A popular alternative to using the JCA architecture to reengineer and reuse legacy
applications is to implement a Service Oriented Architecture (SOA) . When
migrating a legacy software system to an SOA, application programs that are candidates
for reuse are identified. Typically, candidate applications should be well structured such
that the business logic can be isolated, encapsulated, and made into reusable components.
These SOA components become capable of communicating without the tight and fragile
coupling of traditional binary interfaces because they are wrappered with a platform-
neutral interface such as XML and Web services. Once a business or organization has
created a collection of reusable components from stable and well tested code, it becomes
possible to quickly assemble new applications without having to rewrite and test the