What was promised by SOA is not just limited to the cost savings and minimizing effort of application development process, but the critical benefit when you using SOA is the application must be able to answer the current (fast) market demands.
Here are some approaches to start your SOA:
1. We can start by building from scratch a few services or rewrite an existing application into services. The advantage of this approach is the service that we build can be maximally reuse in the future. Of course, this approach takes time and effort compared to most other approaches.
2. We can create programs that already exist into service oriented. This can be done on the programs that have been built in a modular fashion, just add the techniques of web services in it. So, we can make the service interface without changing the existing logic. Thus, the test was sufficient on its interface only, while the function / logic in it does not need more tests because they are not change.
3. Applications that already exist, especially applications that are purchased in packages such as ERP, CRM and others, can be “wrapped” to be invoked via web services interfaces. Of these applications, we can make some services starting from the lowest level services such as Customer Lookup to the highest level such as the Create Invoice. Low service level can be merged into the new service are higher, such as Fund Transfer service is built on service Validate Account, Check Balances, Debit Accounts and Credit Accounts. This approach is very good, considering some of the SOA vendors provide adapters for several popular application packages such as SAP, Siebel and others. Thus, the business logic in it can be published as services.
4. Services can be purchased from a third party (eg a company credit rating information service provider). Currently, vendors are modifying their products into services that can be invoked by web services.
By building a collection of services, the savings can begin. The first project is usually time consuming and laborious. Believe me, the effort spent on the next project will be smaller because it has many available services as a result of previous projects that can be reuse. In addition, processing time is also faster, allowing companies to deliver business services more responsive to market demands. And if this involves increasing the number of transactions or customers, then the return value from SOA projects are financially more real.