Service oriented architecture - 1

SOA, Yes, it expands to Service oriented architecture. What is it?

Keep these things in mind during design and analysis.

1. Whenever you design a service, you are designing a service for a business task.

2. These services can be linked to achieve bigger business goals.

Let us understand 'Service':

In my view, a service is an expectation fulfillment for a service consumer, without service consumer actually worrying about how is it fulfilled.

For example: A student opts of 'Data structures' lesson. The delivery of a lesson is a service for the student. The professor does his homework, examples and makes sure that student understands the lesson. Student and the professor are the different entities, yet there is a well defined service contract between them which enabled two entities exchange the expectation without student actually worrying about the service implementation aspects of the professor.

So, to be called a service, it should be meaningful. It should satisfy the certain expectations. It should be bound by well defined interfaces. Any design that is designed keeping 'service definition' in mind, is a service oriented design.

SOA is an architectural model for integrating business partners', customers' and suppliers'services into enterprises' business processes. 

Why SOA?

• Promotes reuse of IT investment in a business [will touch upon example, later]
• Promotes greater IT flexibility [will touch upon example, later]
• Greater IT flexibility means business flexibility [will touch upon example, later]
• Helps enterprises comply with government regulations [will touch upon example, later]

SOA is characterized by

- Well defined interfaces between the services.

Barriers for SOA adoption:

• Difficult to justify ROI [will touch upon reasons, later]
• Build vs Buy justification
• New IT investment or use existing IT investment
• Complexity of legacy application [How, will touch upon later]

While designing the services, consider the following:

- Business and IT alignment

- SOA Governance

• Decision rights
• Processes
• Policies
• Controlling aspects
• Monitoring aspects

SOA Governance enables stakeholders to identify ROI.

SOA: DIY Kit

• ESB, for aggregation, routing , transformation
• BPM, for business process orchestration
• Web services, well known means of service implementation

Examples will follow ...