12.23.10
Good and Bad Wrappers
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Wrapping existing application functionality can provide a quick path towards Service-Oriented Architecture. When working with legacy systems, wrapping can often show significant benefits to a project using Service-Oriented Architecture.
In reality though, there is a much greater downside. Most wrapping is done by aligning the services provided to existing functionality rather than basing the service on a well-defined business model. By simply aligning to the existing functionality, the gains expected from the new architecture will not materialize. The same code, with its entire accidental architecture, will still exist with all of its costs.
These costs include operating and maintaining the legacy systems. Operating the legacy environments leaves the hardware and legacy infrastructure intact. Maintaining the legacy systems is further complicated by the service mapping to the older environment.
Wrapping legacy systems to gain a step up in Service-Oriented Architect may simply come down to using software in ways it was not intended to be used. The consequences could result in little benefit.
Wrapping can be good when it is done from well-defined business models. The services would be defined according to the business requirements coming out of the models. In this case, the mapping of the legacy system may require some additional effort to adhere to the model.
What is good, when taking this approach, is real costs can be evaluated. The cost of making the service adhere to the model can be evaluated against creating an entirely new functionality and replacing the legacy environment. The total cost of ownership can be considered.
Wrapping that is based upon simply gaining access to existing functionality is more often another form of duct tape being applied for short-term gains. Model-based wrapping with alternative evaluation supports the long-term and will provide the best total cost of ownership.
Enterprise Architects are well-aware of the continuing evolution of technology. They creatively look for technology convergence that can provide breakthroughs in thinking. We are at one of those convergent junctions today. What is about to happen will give non-professional information technologists control of their use of automation in their business. No longer will they simply peer through windows and see only what applications let them see. They will be able to go inside, see how things work, and control their automation. – Enterprise Architects Masters of the Unseen City
Closing the Business / IT gap.
