email article printer friendly

Make Application Integration Easy
Limited reusability, multiple data formats, tight coupling, and many other problems have hampered easy integration, but SOA can change all that
by Rag Ramanathan

August 20, 2004

Application integration is one of the most critical issues faced by enterprise information technology managers. Enterprises use many custom-built and off-the-shelf packaged applications to run their business processes. These applications must be integrated to share information and to create new applications.

Traditional application development and integration approaches have been inflexible and have not been standards-based; therefore, they have not facilitated an agile enterprise IT environment that can support the changing needs of a dynamic organization.

Development and Integration
In large enterprises, applications must interact with business data from one or more sources, some of which may be other applications. In other words, applications cannot be developed without integration.

On the other hand, application integration requires certain application development tasks, such as developing and assembling components, connecting them to back-end systems, implementing process flows and work flows, developing user interfaces, and testing and debugging. It is no longer useful to consider application development and application integration separately.

Application development and integration methodologies have evolved to allow IT to keep pace with the rapid growth and change of businesses. However, the rate of technology change lags behind the rate of business change. In most enterprises, the IT department's lack of agility impedes the enterprise from changing according to customers' needs.

Three of the most common application integration methodologies were point-to-point integration, enterprise message bus or middleware integration (known as EAI), and business process-based integration.

In point-to-point (or peer-to-peer) integration methodology, applications integrate with other applications as needed (see Figure 1). The interconnections shown could also be built with Web services. That would not make this an SOA-based system, because it lacks other characteristics such as loose coupling, an intermediary base, and shared infrastructure.

Because point-to-point integration was complex, costly, and difficult to maintain, another approach was introduced. This approach was called enterprise application integration (EAI), which was based on a message bus/broker or middleware. In this case, connectivity between the applications and the message bus was developed using proprietary bus APIs and application APIs (see Figure 2).

The business process-based approach improves on EAI. In this case, a business process flow engine is used in conjunction with the message bus or middleware to run process flows that execute multistep transactions with various systems.