Application Integration

Overview
The Application Integration (aka Enterprise Application Integration or EAI) pattern serves to integrate multiple Business patterns or to integrate applications and data within an individual Business pattern. The requirements that gave rise to this pattern 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 replicable patterns. At its highest level, application integration can be divided into two essentially different approaches:

• Process Integration - the integration of the functional flow of processing between the applications.
• Data Integration - the 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 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 integration activity.

Critical to selecting the right Application Integration pattern is an understanding of the integration requirements of the business problem being automated. Some examples of key questions to ask in determining an appropriate EAI design are listed on the EAI Requirements page.

Note
It is worth noting that 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 methods used to interconnect them. For a better understanding of the issues and considerations surrounding an Application Integration solution, review any of the following instructional pages:

• The Application Integration general guidelines page provides additional information on choosing this Integration pattern. Business and IT drivers, the e-business context appropriate for this solution type, and additional solution details are discussed here.
• The Application Integration Services page details a set of services and features commonly required in an EAI solution.
• The Application Integration Solution Requirements page can help determine which of the two EAI categories (Process Integration or Data Integration) you should use in designing your e-business solution.

If you have established a sound understanding of the issues relating to your EAI deployment, the next step is to select an Application pattern. The Application Integration pattern can be implemented using any one of nine different Application patterns. These various designs provide solution flexibility to address the specific needs of the business process being automated. These Application patterns are divided into the two categories described above: Process Integration and Data Integration.