RE: Web Services/SOA - on SOA, and EDA and other TLAs.
> -----Original Message----- > From: Guillaume Lebleu [mailto:gl@b...] > Sent: Tuesday, November 30, 2004 9:47 PM > Cc: xml-dev@l... > Subject: Re: Web Services/SOA - on SOA, and EDA and > other TLAs. > > IMHO... > > EDA (event-driven architecture) does not imply SOA > (Service-oriented architecture). > SOA does not require EDA. > EDA can be useful to implement parts of the SOA. > SOA just requires people to follow the rules expressed in the > service contract (and thus, tools to make it easier to follow > those rules are nice to have). > > more details.. > > IMO, an IT architecture is all about providing the > constraints for IT organizations to deliver working software, > whether it is during development, testing, production, maintenance. > > In an SOA, the constraints are that every software > components' interface is described in a unique language and > published in some central location. XML and XML Schema just > happens to be good enough technologies to get the job done, > particularly in massively heterogeous environments. > > Of course, in a real project, you want to add more > constraints than that, for instance security contraints, > transactional constraints, semantic constraints, etc., but > this is currently left to IT architects, although they can > pick from WS-* specs but then suffer interoperability issues > that SOA was supposed to solve... > > On the other hand, the notion of Event-Driven Architecture > implies to me an architecture where you have: > - events, > - a dispatcher (which may produce events themselves, for > instance alerts) > - and event handlers (which may produce events themselves). Excellent points. I consider the above list to be "active" features (please see next comment below for the rest of this point). > Of course, SOA does not require EDA and EDA does not imply > SOA, but EDA could be a nice part of an SOA, for instance, > IMO, in terms of monitoring (they call it BAM - Business > Activity Monitoring), In this context, BAM seems to be a "passive" feature - that is, monitoring what has already occurred. That does not seem to me to be the essense of EDA. I may be misunderstanding your point. Kind Regards, Joseph Chiusano Booz Allen Hamilton Strategy and Technology Consultants to the World > so I would follow Jason Bloomberg of > ZapThink on this: EDA is not opposed to SOA, but rather > included into SOA.(1) > > I think the most important thing about SOA is that languages > and platforms don't matter anymore, so you can choose the > implementation language that fits best the requirements, as > long as it satisfies the service contract. > > (1) http://www.zapthink.com/report.html?id=ZAPFLASH-06092004 > > Guillaume Lebleu > Brixlogic > > > > > > > Chiusano Joseph wrote: > > >>-----Original Message----- > >>From: Bullard, Claude L (Len) [mailto:len.bullard@i...] > >>Sent: Tuesday, November 30, 2004 1:21 PM > >>To: 'Michael Champion'; xml-dev@l... > >>Subject: RE: Web Services/SOA (was RE: XML 2004 > >>weblog items?) > >> > >>Are services responses to events? > >> > >> > > > >I believe they are, though some consider this a > >separate-but-related-to-SOA concept. I believe Gartner has a concept > >called Event Driven Architectures (EDA), which - if I recall > correctly > >since reading up on it months ago - they consider as another > >architectural style (i.e. apart from SOA), but related. > > > >In essence, the invocation of a service is an event in and > of itself - > >for example, the receipt of a purchase order by a supplier that is > >using Web Services in a SOA can trigger the processing of > the purchase > >order and (if all goes well) the creation and transmission of an > >invoice. So the events here would be the receipt of the > purchase order, > >the validation of the purchase order, etc. > > > >Kind Regards, > >Joseph Chiusano > >Booz Allen Hamilton > >Strategy and Technology Consultants to the World > > > > > > > >>That is likely at least one level higher in the organizational > >>architecture if call and response is the lowest level of > description, > >>but if we are to speak of a 'services oriented > architecture' that is > >>meaningful beyond the most primitive descriptions, it can > be useful to > >>think in terms of event types over messages. Otherwise, a > service and > >>a method are indistinguishable. I'm not sure the fact of > using XML to > >>send and return the request or the opacity at the boundary > are enough > >>to distinguish a service from a method invocation, remote or > >>otherwise. > >> > >>len > >> > >> > >>From: Michael Champion [mailto:michaelc.champion@g...] > >> > >>For what it's worth, all these discussions beg the question > of what a > >>"service" is. I've taken a stab at this in > >>http://www.cioupdate.com/trends/article.php/3434691 > >> > >>'In the real world, we use services all the time -- getting > money from > >>banks, ordering food from a restaurant, getting clothes dry > cleaned, > >>and so on. What makes these "services" > >>is that we don't need to know anything about banking, cooking, > >>cleaning, etc. in order to use them, we simply request them. > >> > >>...In a nutshell, service orientation is an approach to designing > >>systems in which each component knows only how to request > and consume > >>the services provided by other components, and little about their > >>internal algorithms, data structures, stored data formats, query > >>languages, etc. > >> > >>----------------------------------------------------------------- > >>The xml-dev list is sponsored by XML.org <http://www.xml.org>, an > >>initiative of OASIS <http://www.oasis-open.org> > >> > >>The list archives are at http://lists.xml.org/archives/xml-dev/ > >> > >>To subscribe or unsubscribe from this list use the subscription > >>manager: <http://www.oasis-open.org/mlmanage/index.php> > >> > >> > >> > >> > > > >----------------------------------------------------------------- > >The xml-dev list is sponsored by XML.org <http://www.xml.org>, an > >initiative of OASIS <http://www.oasis-open.org> > > > >The list archives are at http://lists.xml.org/archives/xml-dev/ > > > >To subscribe or unsubscribe from this list use the subscription > >manager: <http://www.oasis-open.org/mlmanage/index.php> > > > > > > > > ----------------------------------------------------------------- > The xml-dev list is sponsored by XML.org > <http://www.xml.org>, an initiative of OASIS > <http://www.oasis-open.org> > > The list archives are at http://lists.xml.org/archives/xml-dev/ > > To subscribe or unsubscribe from this list use the subscription > manager: <http://www.oasis-open.org/mlmanage/index.php> > >
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