Harm Smit wrote: > > -1. > Anne, I don't know which "traditions" you are referring to for a > discipline that is only a few years old. Yes, I know we disagree on > this point: to you, CORBA and DCOM are also SOA -- to me, SOA is no > older than Web Services. But maybe this is precisely why we > are diverging here: could it be that your position is inspired by the > heritage of the distributed object paradigm? As the draft OASIS SOA > Reference Model puts it in its section "How is SOA different?": "To > use an object, it must first be instantiated, while one interacts with > a service where it exists". IOW, in SOA there is no notion of > instantiation.
> Furthermore, it seems to me that quite some confusion stems from not > distinguishing between abstract services and the actual > implementations thereof, through the corresponding service providers. I guess I'm more in Anne's camp. SOA certainly as the words indicate is a paradigm. It should have nothing to do with the technology that enables it. The work done in Web Services seems to be pretty much parallel to the earlier work in CORBA. I can match most of the work one-to-one. In fact, the mapping between WSDL-IDL is pretty much a one-to-one mapping. This issue of "instantiation" is a "red herring". The service has to be "instantiated" to be available. T here is nothing in the CORBA world that says one has to instantiate an object. The issue is how does one get a reference to an object. That could be a URI or a object reference. There is no real difference other than the way it is expressed. > > Taking your stock quote example, let's assume there is just one > universal abstract stock quote service. But that doesn't mean there is > just one universal stock quote service provider, and one may have very > good reasons to prefer one service provider over another, e.g., > because they don't cover the same range of stock symbols. Of course not. What does this have to do with the issue? Similarly below. "lightbulbs" implementing an abstract service is the same as a distributed object. Just a different name for it. With CORBA, you can use and instantiate objects or not, as you please. If you look at a number of the OMG standards the fit the SOA model perfectly and can be triviallly implemented in Web Services. To not call them SOA is to ignore the high level architecture view of SOAand claim it is only attached to a technology. This does disservice to the industry and to users of these services. The value of the term SOA for the user and industry is to "finally" make people aware of the importance of services to the enterprise rather than one-off applications. Dave > Similarly, when invoking the services of a smart lightbulb, I'd need > to know whether it's the lightbulb in the kitchen or the one in the > bathroom. But both lightbulbs would implement the same abstract > service, even if they werfrom different vendors. > > HTH, Harm. > > > > -----Original Message----- > *From:* [email protected] > [mailto:[EMAIL PROTECTED] *On > Behalf Of *Anne Thomas Manes > *Sent:* vendredi 14 juillet 2006 20:06 > *To:* [email protected] > *Subject:* Re: [service-orientated-architecture] Zapthink on SOA/REST > > +1. In a traditional service-oriented approach, a service > implements a function that can be performed on multiple instances > of a resource. You do not have a different service for each > resource. .e.g, you have a stockQuote service -- you input a stock > symbol and it returns the stock quote for that stock symbol. You > don't define a separate service for each stock symbol. The latter > would be a resource oriented approach -- and it makes much more > sense to use a uniform interface( i.e., REST) when using a > resource-oriented approach. > > Anne > > On 7/14/06, *Stefan Tilkov* <[EMAIL PROTECTED] > <mailto:[EMAIL PROTECTED]>> wrote: > > On Jul 14, 2006, at 9:52 AM, Harm Smit wrote: > > > The latter is rubbish. It should read: lightbulb10.turnOn() > > Each lightbulb is an independent, autonomous service provider. > > That's the first time I've seen someone make that claim for > SOA-style > services. > > Stefan > -- > Stefan Tilkov, http://www.innoq.com/blog/st/ > > _._,___ ------------------------ Yahoo! Groups Sponsor --------------------~--> Great things are happening at Yahoo! Groups. See the new email design. http://us.click.yahoo.com/TISQkA/hOaOAA/yQLSAA/NhFolB/TM --------------------------------------------------------------------~-> Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/service-orientated-architecture/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
