Integration Problems

Interesting applications rarely live in isolation. Whether your sales application must interface with your inventory application, your procurement application must connect to an auction site, or your PDA’s PIM must synchronize with the corporate calendar server, it seems like any application can be made better by integrating it with other applications.

All integration solutions have to deal with a few fundamental challenges:

• Networks are unreliable. Integration solutions have to transport data from one computer to another across networks. Compared to a process running on a single computer, distributed computing has to be prepared to deal with a much larger set of possible problems. Often times, two systems to be integrated are separated by continents and data between them has to travel through phone-lines, LAN segments, routers, switches, public networks, and satellite links. Each of these steps can cause delays or interruptions.
• Networks are slow. Sending data across a network is multiple orders of magnitude slower than making a local method call. Designing a widely distributed solution the same way you would approach a single application could have disastrous performance implications.
• Any two applications are different. Integration solutions need to transmit information between systems that use different programming languages, operating platforms, and data formats. An integration solution needs to be able to interface with all these different technologies.
• Change is inevitable. Applications change over time. An integration solution has to keep pace with changes in the applications it connects. Integration solutions can easily get caught in an avalanche effect of changes – if one system changes, all other systems may be affected. An integration solution needs to minimize the dependencies from one system to another by using loose coupling between applications.