Ten Things to Think When Building SOA

David Linthicum wrote another excellent article. The tips (listed below), in fact, tell us what to do and what NOT to do regarding SOA implementation. Let's see the " rules" with my notes:

1. Focus holistically, act locally: SOA is NOT a project. SOA is a path that not ends, like quality (in an broad sense). SOA is the sum of many parts and you should take them in count when implement you architecture.
   
2. Define the value: Strategy is important, better, a business case. If you defined that SOA is the new architecture approach for you company, how it can happens if there is no guideline that will make this happen?
   
3. Don't neglect service design: What we have behind composite application and composite process?... ...Services! So, they deserve special attention. Web Services must be design to be reused, to provide behavior and information (not to be app specific), must be aware of hardware and O.S. (no calls to native interfaces).
   
4. Leveraging a legacy is unavoidable: What keeps our business running? Legacy systems! Service-oriented architecture came to allow you to take the best from these legacy systems, not to rewrite them.
   
5. Remember the semantics: When dealing with data think about the real meaning of them, the context of this information, the semantic... ...ask yourself which relevant information you can extract from this data?
   
6. The proper place for orchestration: SOA implementation does not necessarily need orchestration to run. However, consider it for some application.
   
7. Security soaks in as you execute; it's not an afterthought: You might firstly developer Web Services for internal use, but in a near future they can be used for other companies (partners). Think about Identity Management from the beginning.
   
8. Classify the patterns of use: Three rules when implementing Web Services: patterns, patterns and patterns.
   
9. Persistence is important: "... You need to think about persistence for a few reasons, including federation of services around the SOA. When building an SOA you may end up with composites or processes created out of services that may exist over a dozen or more different systems, and as such, persistence becomes more complex if done at the points...".
10. Don't skimp on testing: Keep in mind that most of the data and system that Web Services will deal with are business-critic. Thus a test plan is very important and this must be written from the beginning.