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Subject: RE: [soa-blueprints] The Myth of ESB... is it a blueprint or a pattern...
+1 on the wiki zone for schema's (a perennial thorny issue IMO) ESB as myth - my 'take': A Service Bus is any communications environment that supports composable layers of interaction that include reliable messaging, event notification, publish-and-subscribe, transformation, routing, orchestration, security, and more. As such it appears more as a logical label for architectural Blueprinting IMO. Composable layers of robust interaction may be implemented within "all-in-one" ESB, EAI, and other integration ware offerings. Enterprises may use several integration ware offerings--from the same or different vendors--to provide multiplatform interoperability, therefore are there different "ESB's" within an Enterprise? Likely. Most vendors' market-offerings for 'ESB' blur the boundaries between this approach and older "paradigms." Many vendors provide ESB, EAI, EII, BPM, MOM, integration broker, and Web services offerings under comprehensive integration product families - with a consequence of creating multiple additional layers of integration/abstraction. Hmm, I think I'm persuading myself of the case for a blueprint (blurprint?) so as to normalise an open-standard against vendor-specifics (give a target and 'straightforward' interoperability is more assured) 10 cents worth :) I'll now wait for someone to explain where I missed an obvious point ... while I have another chortle over Steve's fabulously inventive Christmas model... :) Marc -----Original Message----- From: Miko Matsumura [mailto:email@example.com] Sent: 07 December 2005 15:25 To: Eric.D.Friedman@wellsfargo.com; firstname.lastname@example.org; email@example.com; firstname.lastname@example.org Subject: RE: [soa-blueprints] The Myth of ESB... is it a blueprint or a pattern... I think Ash is indicating the role of the repository as a system of record for things like service contracts and policies. As such, you can indicate whether service consumer A should get service version 1 and consumer B should get version 2 and you can deal with migration and other change time governance issues. The in flight stuff etc is definitely happening in an intermediary, but perhaps one that talks to a repository. Registry from an OASIS perspective typically means UDDI, whereas repository can mean a lot of things including ebXML RegRep, source code control systems, databases, file systems and just about anything under the sun. +1 on this distinction being poorly specified. The schema problem is a very hard one, and as such quite interesting. perhaps we should create wiki areas for this topic as well as some of the other major topics that have been emerging... -----Original Message----- From: Eric.D.Friedman@wellsfargo.com [mailto:Eric.D.Friedman@wellsfargo.com] Sent: Tue 12/6/2005 10:21 AM To: email@example.com; firstname.lastname@example.org; email@example.com Cc: Subject: RE: [soa-blueprints] The Myth of ESB... is it a blueprint or a pattern... Ash, I assume you mean "should [versioning] happen inside an ESB or a SOA Repository?" as the other things that are happening, like fan-out, in-flight transformation, aggregation, filtering, etc. are all runtime "orchestration" activities that (to my mind) belong in an ESB. I confess to being ignorant about SOA Repositories - will assume that's another word for registries, like UDDI. Finding services is not a problem in our environment. Building services (and consumers of them) that upgrade gracefully is a big problem. This is so for a couple of reasons. One is that with multiple service providers in different business lines, it's not unusual to get into a situation where provider A is using version X of a common entity schema (for things like 'account') and provider B is using version Y. But consumers C-M need both services (and others besides) and they need them to work together. Provider A will eventually upgrade to version Y, but in the interim, how do M consumers work with N producers given entity definitions that are evolving? There is no easy answer to this problem - short of forced synchronization of upgrades, which is not realistic - so an ESB becomes a place to encapsulate the M*N problem. It does many other things besides, but ensuring that you can take the output of A and use with as input to B is very much an orchestration activity that ESBs are positioned to address. The other versioning challenge lies in schema itself. Dave Orchard, of BEA, spoke thoughtfully about this at BEAWorld a couple of months back and has a few good articles here (http://www.pacificspirit.com/Authoring/Compatibility/ProvidingCompatibleSch emaEvolution.html). The gist of it is that XML Schema presents real challenges for a business that wants to futureproof its SOA investment. I don't know whether this TC would call solutions to those challenges blueprints, patterns, antipatterns, or best practices, but it's difficult for me to imagine anyone being successful with SOA without giving careful thought to these questions. Orchard reports that the W3C group is working on fixes for this problem in future versions of Schema, but clearly the horse is already out of the barn on this one. _____ From: Ash Parikh [mailto:firstname.lastname@example.org] Sent: Monday, December 05, 2005 7:14 PM To: Friedman, Eric D.; email@example.com; firstname.lastname@example.org Subject: RE: [soa-blueprints] The Myth of ESB... is it a blueprint or a pattern... Should this happen inside an ESB or a SOA Repository Eric? Cheers! A S H P A R I K H Director of Development and Technology, EAG Raining Data Corporation (NASDAQ: RDTA) "Technology for Innovative Solutions" www.rainingdata.com <file:///\\www.rainingdata.com\> +1 (510) 673-2922 - Office +1 (510) 372-0432 - eFax email@example.com - Email Co-Chair: SDForum Web services SIG Founding Member: OASIS SOA Blueprints TC _____ From: Eric.D.Friedman@wellsfargo.com [mailto:Eric.D.Friedman@wellsfargo.com] Sent: Monday, December 05, 2005 5:10 PM To: firstname.lastname@example.org; email@example.com Subject: RE: [soa-blueprints] The Myth of ESB... is it a blueprint or a pattern... We're 2+ years into a production ESB implementation in my line of business, so I think I can speak with some authority on this one. Writing services has become easier, but it's still not easy. Having an ESB and an associated team lets us approach services from a 'center of excellence' standpoint. No vendor has come up with good solutions to the challenge of versioning services. Indeed, it's very hard to write XML Schemas that version well - it's a defect of the schema for schemas itself, not just a vendor gap (though it is that too). So, our ESB gives us an opportunity to buffer our development teams against the thrash in the enterprise beyond. Services are often delivered in "one size fits all" format. An ESB is a chance for us, as one of many lines of business, to tailor that service to our own ends, adding caching or applying security and visibility restrictions. This goes to Steve's point about needing to assume that buses are >1 in number. The ESB lets us forward responsibility for certain kinds of complexity. If an enterprise service only provides a SOAP/HTTP interface, we can put an ESB service in front of it that does guaranteed delivery using JMS and then let the ESB be responsible for getting it through to the less-reliable interface. The ESB is the natural place to implement fan-out of parallel service calls. Multithreaded programming is hard enough that we don't want most developers doing it. Doing this sort of thing in the ESB lets it provide "value add" aggregating services that the enterprise will not cover. Looking into my crystal ball, I think the next big push in this arena will be to virtualize ESBs. Today, our ESB is a network-addressable endpoint with SLAs and the whole shooting match. In a heterogeneous computing environment we'll always need that to some extent, but it is reasonable to ask why we'd continue to incur the cost of network indirection for the ESB when we can just co-deploy. Perhaps with the rise of 'utility computing' that will just "happen" in infrastructure and we won't have to think about it. Eric Friedman Wells Fargo Private Client Services Architecture _____ From: Jones, Steve G [mailto:firstname.lastname@example.org] Sent: Monday, December 05, 2005 3:33 PM To: email@example.com Subject: [soa-blueprints] The Myth of ESB... is it a blueprint or a pattern... A question to the group Back in the old "Enterprise Application Integration" days the vendors pushed a model which had either a single broker in the middle, or a bus in the middle. The common element was always that "one" thing in the centre. We are now seeing the same thing with ESB, the concept of a single bus (product) that rules the enterprise. With EAI one of the biggest challenges was that product centric view of the world which led to organisations being left with "legacy" EAI which is as much of an issue as the applications it was meant to make easy to access (any Monk programmers out there?). So what my strawman is to this group (and as the Soalogic thing evolves its quite important) is that concept of bus federation is essential to an SOA Blueprint, you must assume that there will be multiple busses, potentially at all levels, these may use similar technology (even identical) but the principles of federation should be the default for a well formed SOA. Now is this a pattern or a blueprint, and if a blueprint where should it be considered. My viewpoint is that there needs to be an official counterpoint to the vendor view that takes a Lord of the Rings (one ESB to find them all and in the darkness bind them) approach to delivery. The best ESB is the one that assumes it isn't the only thing around. Steve ___________________________________________________________ Steve Jones | Capgemini CTO, Application Development Transformation T +44 870 906 7026| 700 7026| www.capgemini.com <http://www.capgemini.com> m: firstname.lastname@example.org <mailto:email@example.com> txt: +44 (0) 7891157026 Join the Collaborative Experience ___________________________________________________________ This message contains information that may be privileged or confidential and is the property of the Capgemini Group. It is intended only for the person to whom it is addressed. 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