Ashraf, why are you still talking about services while it is absolutely clear that you operate with Web Services? You are not alone, many people do the same, e.g., Service Component Architecture has NOTHINGto do with services, it is good for components and components only ( http://www.ebizq.net/blogs/service_oriented/2009/05/if_you_lost_in_translation_from_sca_into_soa.php ). How many chances to find a match between WS-Policy assertion and SLA of a service that have different ownership? IMO, VERY little unless it is the same person who put the SLA (?) into the Registry (what Registry?).
- Michael ________________________________ From: A W <[email protected]> To: [email protected] Sent: Wednesday, May 13, 2009 3:39:56 PM Subject: Re: [service-orientated-architecture] Re: JP on defining SOA The swapping one out for another is a very good example for changing the service implementation dynamically at run time, better if using a UDDI registry. The consumer just scan the Registry to get the SLA according to some WS-Policy definition in his side, then a decision could be made, either manually or automatically, to swap the other provider if he prefers the price. Another example for Service is implemented as a component. An example is a CICS payment system that runs on IBM mainframe. I wrapped this application an exposed it to different consumers. The Mainframe, the web and the hand-held devices client can use it as is with no modification at all to the service implementation. In addition, it can be used in a synchronous or asynchronous way with no modification to any client or the application itself. The consumer can choose the mechanism that most fit his need, agree with the SLA, and bind to the servcie. All the best Ashraf Galal On Wed, May 13, 2009 at 12:46 AM, Rob Eamon <rea...@cableone. net> wrote: JP, That's a good example. I suppose there may be others as well. I wonder how many such identical (or close enough) services might a typical company encounter in their service portfolio. But I think I erected a strawman anyway. The original point by Ashraf was to be able to change the implementation, which is different from swapping one out for another. -Rob --- In service-orientated- architecture@ yahoogroups. com, "jp_morgenthal" <jpmorgenthal@ ...> wrote: > > Rob, > > Your pragmatism is partially correct here, but the effort need not be > significant. From my favorite example, consider switching from FedEx to UPS > for shipping. Most companies do this hundreds of times a day and the > difference is how they prepare the package for shipping, which ultimately > comes down to prepping the shipping label information. Yet, you can run the > shipping process identically and choose a different shipping provider based > on price with minimal overhead and effort as a single step. > > JP > > --- In service-orientated- architecture@ yahoogroups. com, "Rob Eamon" > <reamon@> wrote: > > > > In other words, service interface is separate from service implementation? > > This is the core SO principle. > > > > I'm still bearish on the notion that a service implementation can be > > swapped out for another with zero consumer impact. I've never seen a > > meaningful implementation of anything be swapped out without significant > > effort. Some low-level technical components can and have been swapped out > > but that's not the level we're addressing here? > > > > -Rob > > >
