Single-Step Application Integration
The Single-Step Application Integration (SSAI) pattern extends the asynchronous database replication pattern. Instead of focusing on data consistency between two databases, the SSAI pattern integrates data between applications, moving data from one context to another. It does so by translating data syntax of the source message and reformatting data elements into a new target message. It is "single step" because it requires an intermediary broker to map source messages to target messages. Typically, it is an extension of the asynchronous replication technology, in that it utilizes Message Queuing Middleware such as MQ Series. It is just as likely to be implemented with the less sophisticated FTP in a batch mode. In either case, the point is that it does more than simply move data from point A to point B for consistency's sake. Whereas, in the replication pattern both the source and target data models are likely similar, if not identical at times, this is not necessarily the case for the SSAI pattern. The objective here is not data consistency, but application data integration. Figure 3.2 illustrates an example of SSAI where message A is directly transformed to message B.
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Figure 3.2 Single-Step Application Integration.
SSAI brokers perform a single-step transformation involving the translation, reformatting, and application of rules to intelligently map data from one point to another. However, the entire "transaction" is still point-to-point in nature. Although integration of multiple enterprisewide applications can be treated as a series of point-to-point integration instances, doing so has limitations and necessitates a more flexible and complex pattern.