August 08, 2003

Altaman on SOA Construction

A few quotes from an article (PDF) by Ross Altman on how to build a SOA. [Found via Gervas Douglas on the Service-orientated-architecture mailing list]

Granularity is the key. Don't define your service layer with fine- grained services. Services should publish and consume large-grained business objects (i.e., entities that your line of business people would understand such as "customer," "order," "sales rep," and "shipment." Each service should be able to perform recognizable actions on each of these business objects (e.g., "add a customer," "change an order," or "confirm receipt of a shipment.")
You should make your services function as black boxes. Developers who consume those services shouldn't have to know how the code behind the SOA interface layer was built. Wrapper and transformation logic behind the scenes should provide the service consumer with a syntactically, semantically consistent view of the multiple, diverse underlying applications rolled together to create your large-grained objects.
The services you'd reuse must be easy to find. If it's easier to build components than find them, your developers will build their own every time. This means that you need a good metadata repository. .... But the metadata describing your services doesn't magically jump into your repository. Someone has to put the metadata in the repository, make it searchable, and maintain it once it's in there. Making it searchable is the toughest part of that trifecta. You have to know a lot about the applications and application development to be able to define metadata that will accurately anticipate how developers might search for reusable components.
Entry categories: Architecture Web Services
Posted by Jorgen Thelin at August 8, 2003 09:38 AM - [PermaLink]
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