Integration of legacy systems into a modern enterprise SOA (part 2)

Integration of legacy systems into a modern enterprise SOA (part 2)

2. What are lagacy systems?

Legacy systems are still wide-spread. Frequently they are defined as IT systems (hard- and software), which are in use for a long time in an enterprise. In the majority of cases these systems (or parts of it) do not run on up-to-date hardware and even if they do, oftentimes the software architecture is not on recent levels. Mostly present-day software and architecture standards like SOA, JEE, Multi-Tier, application server and middleware are not used.

However, those systems are an integral part of some enterprises. Usually, they even today represent their core competence and directly participate in revenue generation (e.g. mainframe, cobol, ...). In addition those systems contain huge development and maintenance effort from the past, for which reason they represent an important factor in enterprise intelligence and -experience.

The many advantages of those inherited systems are obvious. Frequently the TCO is very high, their components are tightly coupled or the architecure is monolithic and not up-to-date. Senior developer and other knowledge carrier have maybe left the company and new demands require much development effort (high "Time-to-Market"). Also the documentation is out of date. These are reasons why in many cases the management thinks about replacement or new product development, but this was refused due to cost and time issues. Also with enterprise takeovers or acquisitions an integration scenario can become necessary. In this case external legacy systems must often be added to the own SOA landscape.

As you can see, there are many reasons, why those systems should be integrated simple, fast, functional and future-proof into modern enterprise architectures (e.g. SOA). This process is called "legacy enablement".

Part 3 will follow next week...