Recently, Kerrie
Holley and Dr. Ali Arsanjani, both IBMers who have been doing intensive work with SOA approaches, compiled the most frequently asked questions being asked about SOA into a new book, titled, appropriately enough, 100 SOA Questions Asked and Answered.
If you have questions about SOA and want to get it straight from two individuals on the forefront of SOA thinking, this is the source. Some of the answers to common questions are not so intuitive, as we often have been led astray by conventional wisdom promulgated by analysts, conference speakers, the media, and (yes) bloggers.
Dr. Arsanjani, for one, is the principle author of the Service Oriented Modeling and Architecture (SOMA) method, which is employed by IBM Global Services in projects across the globe. He is also a fellow co-author of the SOA Manifesto.
Here is a sampling of Q&As explored in the book:
Q: Is SOA an architectural style?
("Of course" you may think -- that's what the "A" in SOA stands for! but read on:)
A: "When pundits, architects, consultants, or executives define SOA as a pure technology play or as solely an architectural style, they relegate it to the realm of SOA science projects..."
Q: What is the difference between a Web service and an SOA service?
(There's a difference? Read on:)
A: "SOA services can be realized as Web services, but not all Web services are equal to SOA services. Web services represent the use of both a published standard and a set of technologies for invocation and interoperability. SOA services are services that fulfill a key step or activity of a business process and can be described as business services and are often exposed as Web services."
Q: How should the business measure the effectiveness of SOA?
(The $6 million question...)
A: "Measuring the effectiveness of SOA starts with identifying specific value propositions and assigning a suitable metric for assessing and tracking... potential metrics: 'improve IT's ability to respond to business needs'; 'speed up delivery time'; 'improve flexibility of applications'; 'improve flexibility of business processes.'"
Q: What are the criteria for selecting a project for SOA adoption?
(Pick the low-hanging fruit, right?)
A: "All projects that create strategic assets of have the intent to differentiate or change the business should be candidates for SOA adoption."
Q: Why do organizations need to focus on SOA governance when there is an effective enterprise architecture activity?
(Good question -- if you have good EA governance, why do you need something else for SOA?)
A: "SOA requires additions to standard enterprise architecture practices and processes. The notion of a central service model, for example, is unique to SOA; enterprise architecture must adjust to address handling of service models as a vehicle to promote sharing across the enterprise."
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