Mark Baker wrote: > > >But RPC's do work > > on the Internet. It is what happens with DNS, LDAP and other services > > that work very well and are the ubiquitous backbone of the Internet. > > I am sympathetic with that view of RPC. I've used it myself in the > past, to try and make a point. Why I don't use it anymore can best > be explained by example ... > > Even if DNS and LDAP used the exact same, perfectly interoperable, RPC > layer, could they interoperate? Could a DNS client get data from an > LDAP server? Could an LDAP client get data from a DNS server? Of > course not. Therefore, even though it is true that these systems use > RPC in the sense that "remote operations are invoked", describing > systems in those terms doesn't help to understand their affinity for > each other. It's an insufficient descriptor.
Why would one expect or want a DNS client to get data from an LDAP server? This has nothing to do with whether RPC's work on the Internet. There is no "affinity" between DNS and LDAP. They are distinct services. I believe they are clear examples of SOA (not WS), since they are services that are available on the Internet. One wouldn't want DNS to talk to LDAP and so there is no confusion. If every application uses the same RPC or API, it would terribly confusing and would result in no interoperability. > > > The semantics of a request must be accomplished regardless of the > > protocol to send the information. The protocol isn't that essential, > > but the semantics of the request is. > > I see that I didn't make my point. 8-( > > Application protocols define application semantics. They are not > "protocols" in the same sense of the word used in systems like CORBA, > DCOM, RMI, Jini, etc.. IMO, that's the root cause of the > misunderstanding. If these things had been called "locotorps", this > confusion wouldn't exist; "protocol independence" would be a good > idea, since protocols just move bits around. But "locotorp > independence" would be silly, because everybody knows that locotorps > define the application semantics, and how can an applications be > independent of application semantics?! 8-) Yes. Using "protocol" for how bits on the wire are organization and application semantics is a bad idea. http is a protocol. iiop is a protocol. How a client talks to a server semantically has nothing to do with protocols in the computer science sence. > > Consider these two (short-cut) example HTTP messages, both reusing > the document from Anne's document-oriented example; > > POST some-uri HTTP/1.1 > Content-Type: application/soap+xml > <env:Body> > <m:purchaseOrder xmlns:m="someURI"> > ... > </m:purchaseOrder> > </env:Body> > > vs. > > PUT some-uri HTTP/1.1 > Content-Type: application/soap+xml > <env:Body> > <m:purchaseOrder xmlns:m="someURI"> > ... > </m:purchaseOrder> > </env:Body> > > Those two messages have different application semantics. The former > means "process this SOAP envelope", the second means "store this SOAP > envelope". I agree. The method call affects the semantics. That is what RPC's do as well as any other type of distributed computing. So I'm missing the real distinction or message here. If one only as PUT and POST one is severely limited on the type of application semantics that one can express. Sending all communications over these type of "method" calls is pretty limiting or requires one to add the application semantics to the messages. Thanks, Dave > > Mark. > -- > Mark Baker. Ottawa, Ontario, CANADA. http://www.markbaker.ca > Coactus; Web-inspired integration strategies http://www.coactus.com > > > > ------------------------------------------------------------------------ > YAHOO! GROUPS LINKS > > * Visit your group "service-orientated-architecture > <http://groups.yahoo.com/group/service-orientated-architecture>" > on the web. > > * To unsubscribe from this group, send an email to: > [EMAIL PROTECTED] > <mailto:[EMAIL PROTECTED]> > > * Your use of Yahoo! Groups is subject to the Yahoo! Terms of > Service <http://docs.yahoo.com/info/terms/>. > > > ------------------------------------------------------------------------ > ------------------------ Yahoo! Groups Sponsor --------------------~--> Get Bzzzy! (real tools to help you find a job). Welcome to the Sweet Life. http://us.click.yahoo.com/A77XvD/vlQLAA/TtwFAA/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/
