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CHAPTER 3 Getting Started with SOA

The secret of getting ahead is getting started. The secret of getting started is breaking your complex overwhelming tasks into small manageable tasks, and then starting on the first one. —MarkTwain

We defined SOA as an architectural style promoting the concept of businessaligned enterprise services as the fundamental unit of designing, building, andcomposing enterprise business solutions. So how do you go about designing and building solutions and the services that support them? This chapter covers the role of the SOA methodology in the creation of enterprise SOA solutions and the methodology’s major steps. For each step, a high level overview of its goals, requirements, and activities is provided.

The details of these steps are the topicof the rest of the book. In general, each major step in service design is covered in a chapter later on. Specifically, in this chapter, we cover:

* An overview of SOA methodology
* Defining the reference architecture
* Defining the business architecture
* Information design
* Identifying services
* Specifying services
* Implementing services
* Service designprocess

Finally, we end with some practical suggestions for getting started.

Overview of SOA Implementation Methodology

Enterprise SOA defines a set of business-aligned IT services (available to participants throughout the enterprise across multiple lines of business or even outside of the enterprise) that collectively address an organization’s business processes and goals. Theseservices can be combined in a variety of different ways to support enterprise business processes and business solutions. By ensuring that there is a business focus of its main constituents (business services and business processes), the SOA architectural style promotes alignment of business requirements and technology solutions. Both processes and services are driven by the business architecture andcan be traced back to the business outcomes that they help to realize. The major forces shaping the SOA architecture and its major elements are shown in Figure 3-1 and discussed in the following list:

* The forces that drive the business and SOA — the enterprise business drivers — are at the top. These are things like strategy, competition, market forces, regulatory forces, and so on. Theyall combine to drive the business architecture (model) and to shape the measurement and feedback for enterprise-wide performance management.
* The business model is the representation of the business resources and processes that are required to meet enterprise operational, tactical, and strategic business goals. Having a business model is critical to the successful alignment of services withbusiness goals and objectives, and consequently to the overall SOA implementation’s success.
* The semantic information model defines the common business information for a given enterprise (such as customer, agreement, etc.). These objects effectively create an ontology of the enterprise data by defining common concepts (and their content) that describe the operations of the enterprise. Usingthe semantic information model to define business service interfaces leads to the creation of semantically interoperable services — a semantic SOA.
* Other aspects that enable SOA to provide value are: key performance indicators (KPIs) and portfolio rationalization. The KPIs enable quantitative assessment of the impact of SOA and allow business processes and services to be measured andoptimized. Portfolio rationalization enables the enterprise to simplify and consolidate infrastructure, applications, and data, where SOA plays a leading role in the implementation of the consolidation activities.

Figure 3-1 Major elements of enterprise SOA

* In terms of implementation, the primary aspects are business processes and services. The business processes orchestrate the execution...