What do you call the procedures by which you take your existing software and information assets and enable them to be used in new business processes? I've heard several phrases used: enterprise modernization, legacy transformation, legacy enablement, legacy modernization, and so on. I suspect you've heard even more permutations of these and perhaps some new ones as well. Of the ones I listed, my favorite is the third, legacy enablement. For some people, though, the word "legacy" has negative connotations, though it really should not.
Legacy software is the software installed yesterday as well as what was put in place fifteen years ago. It is very likely the software running critical business processes. It may have come into the enterprise as a result of a merger or acquisition. When a vendor with little enterprise experience tells you that it needs to be replaced, it is the software that causes you to start laughing hysterically.
Fundamentally, "legacy" means the existing IT assets deployed in the IT infrastructure. This represents a significant amount of the value to businesses. To give an idea of the importance of legacy software, it's been estimated that there are over 200 billion lines of COBOL code in existence, 70 percent of the world's business data is processed by COBOL applications, and 30 billion COBOL-based transactions are processed daily. Clearly, these are tremendously valuable assets to leverage.
There are both cost and competitive challenges in maintaining legacy systems. Large deployments can be costly and investment for new or replacement solutions can be expensive as well. This means to attempt to maintain both old and new systems there may be unnecessary duplication and a development staff that has an exceptionally broad range of skills is required.
From a business and competitive perspective we can sum up the requirement in one word: speed. Businesses need to respond rapidly to market opportunities and be first to market. At the same time, businesses need scalable, reliable, and secure production applications. Taken by themselves, neither the old or new technologies may result in a solution that is cost-effective, complete, or flexible enough to provide the qualities of service you need to deliver to customers. There needs a bridge that can incrementally extend existing assets while offering the advantages of new technologies like Web services. Luckily, there is such a bridge and it is called "service-oriented architecture" (SOA).