Let me continue Mike's line. 

Not only " "non functional" aspects of a service will depend mostly on how the 
service is *implemented*" but some functional ones also. This is the difference 
between SOA Service and REST or WS-* (Web Services). Example? Here you are – 
the provider changes the accuracy of risk calculations behind immutable 
interface and the consumer gets directly affected by new values in old format. 
This is why we need Service Contracts in SOA in addition to the interfaces, 
unified or not.
 
 In SOA, the consumer requires certain behavior of the provider behind the 
interface because it is the business relationship. Can REST or WS-* provide 
such thing per se?
  
- Michael

Mike Glendinning <[EMAIL PROTECTED]> wrote:                                  
--- In [email protected], "Anne Thomas 
 Manes" <[EMAIL PROTECTED]> wrote:
 >
 > Let me reiterate. REST is about the way you design/implement a
 > capability (i.e., a service). If you abide by the REST constraints,
 > your service will exhibit a number of desirable characteristics, such
 > as simplicity, scalability, performance, reliability, evolvability,
 > maintainability, visibility, and portability.
 
 Oh come on, Anne!  Aren't you overstating the case just a little bit 
 here?  I hope Burton Group clients receive somewhat more thoughtful 
 analysis than this!
 
 Surely these "non functional" aspects of a service will depend mostly 
 on how the service is *implemented*, for which the REST constraints 
 provide no guidance.
 
 If I model my resources poorly, or code my services badly and using 
 inefficient programming techniques, the services will not exhibit any 
 of the qualities you suggest, despite my conformance to all of the REST 
 principles.
 
 To expect otherwise is about as silly as thinking that just because I 
 define similar attributes of a service using WS-Policy, or even store 
 these in a SOA registry, that this will ensure that my service 
 implementation will actually *meet* the declared requirements.
 
 The success of any WS/SOA or REST initiative is still reliant on good 
 quality engineering practice.  The adoption challenge for both is to 
 find ways to bring this within reach of the average developer and IT 
 organisation.  This might be done through tools, patterns, documented 
 best practices or otherwise.
 
 Regards,
 
 -Mike Glendinning.
 
 
     
                       

 
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