Step 4: Quantify Pilot Results
The most important deliverable for an SOA pilot is quantified results. Senior management often requires ROI calculations as well as tangible proof of your pilot's success. Create a method for ongoing data capture, particularly if a pilot is conducted over a large period of time, so that the data is both accurate and readily available at the completion of the project. Gathering and compiling these figures is the key to budget justification for the next phase of any SOA initiative (see Figure 4).

SOA Can Be Measured by Several Factors
Reuse of Shared Services
The number of instances in which a shared service is reused is an effective SOA measurement for ROI. Each reuse results in cost avoidance or reduction of building, maintaining, and operating a single-purpose service. In order to properly calculate ROI of shared services, some additional base metrics are needed:

• Costs to build/operate/maintain a shared service. This is the cost of having a shared service.
• Cost to build/operate/maintain a single-purpose service. This should be similar to that of a shared service if your SOA infrastructure is effective.
• Cost to use an existing service built by someone else. This is the cost incurred by reusing a service (the alternative would have been to build a single-purpose custom service). Controlling this metric is critical to SOA success. The reuse of a service is effectively an integration - and so your SOA needs to be structured to control the costs of integration.

Web Services Adoption
The number of Web services created is not actually a measurement of SOA. Instead, it primarily reflects the breadth of adoption of the underlying technology. In many cases, this metric can actually be used as a negative indicator of SOA failure. That is, if a large number of services exist, but few are reused, this may be an indication that your SOA initiative needs some revision.

Business Responsiveness
Compare the time it takes to change or add a feature to a non-SOA-based application with a similar features change to a service.

Conclusion
In addition to the aforementioned methods of measurement, every project will have its own unique business justifications and associated measurements. For example, exposing customer information via a service in order to create a self-service customer portal may be used to significantly reduce call center operations costs. These benefits will, of course, differ for each project. Even if you define a formal SOA pilot project, don't do this for the sake of moving to SOA - the project should provide value to the business.