Chapter 3: Application Integration Pattern

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The Application Integration patterns capture commonly observed solution alternatives in the domain of Enterprise Application Integration (EAI). They capture best practices around back-end integration of applications and data, process automation, and workflow implementations involving human interactions. It is important to note that front-end integration such as the composition of a portal or single sign-on across multiple applications is captured by the Access Integration pattern.

The Application Integration pattern can be implemented using any one of the four Process-focused application patterns and the Data-focused application patterns. These various designs provide solution flexibility to address the specific needs of the business process being automated.

3.1 Using the pattern

Within the context of Patterns for e-business, Application Integration patterns are used at two different levels:

• To design complex solutions by combining more than one Business pattern. An example might be creating an e-commerce site by combining Self-Service and Information Aggregation patterns.

• To support the implementation of a given Business pattern. For example, it is hard to imagine the Self-Service::Decomposition application pattern without leveraging the Application Integration best practices. Similarly, all the Application patterns for Extended Enterprise are in one sense the implementation of Application Integration across organizational boundaries.

Typically, the requirements that drive application integration call for the seamless execution of multiple applications and access to their respective data in order to automate a complex, new business function. Reliable integration of applications - be they legacy stovepipe applications, packaged software applications, or custom applications - requires the use of proven, repeatable patterns. At its highest level, application integration can be divided into two essentially different approaches:

• Process-focused integration: The integration of the functional flow of processing between the applications.

• Data-focused Integration: The logical integration of the information used by applications.

Neither approach is necessarily better than the other. Rather, specific integration requirements dictate which approach best solves a given business problem. For example, the integration of an e-commerce application with an Enterprise Resource Planning (ERP) system for a newly created sales order would most definitely be a Process-focused integration activity. However, in the same solution, the master data synchronization of the product catalog between the ERP system and the e-commerce system would be a Data-focused integration activity.

Note 

Certain types of integration between applications can be accomplished at the user interface level as well, as covered in the Access Integration pattern.

What's next

Enterprise Application Integration is a complicated undertaking. It requires, first, a thorough understanding of the individual applications being integrated, and also the possible methods that can be used to interconnect them.

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