Last mile

The most challenging aspect of service-oriented architecture is the final connection to existing applications and systems. Exposing your enterprise systems and managing the necessary linkages has been dubbed "the last mile problem" by software integration specialist David Linthicum.

In order to effectively address the last mile problem, Linthicum encourages SOA specialists to:

1. Create a catalog ofpotential services, or existing application functions;
2. Figure out a strategy for exposing those services;
3. Document the data and structures bound to those potential services; and
4. Determine a strategy to test the exposed services, making sure the exposed services function and perform correctly.

If suchdiscipline is not imposed on the development and integration process, the whole thing may end in tears. "The hardest part of integration is linking your existing systems to your SOA and seeing those systems as a true set of services," he says. "This point is also where most IT shops fall down, not able to make the walk down that last mile."