12.5 Summary

The target architecture in this phase of the modernization planning process is a high-level design that cannot always anticipate and accommodate all implementation details. Some details may impose demands that conflict with the architecture. In these cases, it may be necessary to either reevaluate the architecture or determine what can be done to accommodate the additional demands.

The architectural patterns included in this chapter provide templates to create an architecture for a system based on the J2EE platform for business objects and XML Messaging, based on OAGIS, for communication between systems. The information in this chapter can also be used to identify and resolve potential design risks resulting from inconsistent or contradictory requirements.

Applying these architectural patterns should result in a system with the following characteristics:

• Fulfillment of the data requirements

• Capability of communication with other systems through a BSR interface

• Compliance with the given technical requirements

• Decoupling of data components from data representation

• Conservation of ACID properties for transactions provided by the EJB framework

• Use of J2EE design patterns representing best practices

As always, sound engineering judgment should be used in applying the architectural patterns included in this chapter, because it is difficult, if not impossible , to predict all possible scenarios. This architecture should be maintained and updated to reflect lessons learned during early iterations of the development process.