+1 I completely agree with you Rob. With SOA the focus has to be on reliable, long-running conversations, not just reliable message delivery. I had a blog entry on this a while back in the context of SQL Service Broker's support for reliable dialogs: http://blogs.objectsharp.com/cs/blogs/pmadziak/archive/2007/02/19/ssb-wcf.aspx
Also, from a pure EAI/Messaging perspective, many of Hohpe & Woolfe's EAI patterns touch on this, for instance: http://www.eaipatterns.com/CorrelationIdentifier.html and an example that uses it: http://www.eaipatterns.com/SystemManagementExample.html Peter On Wed, Dec 10, 2008 at 11:36 AM, Rob Eamon <[EMAIL PROTECTED]> wrote: > Most of the responses seem to address making sure the > intermediary/broker doesn't lose the message. Generally speaking, > that's not where the problem lies. Open source and commercial > products are largely rock solid in this regard--and performance > generally is not a problem (except when someone publishes a few 100+ > MB sized messages!). > > The problem is usually with the end points, where the handshake > between broker and end-point says "got it, thanks" but then the end- > point fails for some reason. Another concern is in "reconnecting" > publisher-side info with subscribers' side info for correlation and > tracking. I've seen very elaborate schemes employed to track and > matchup both sides, trying to proactively detect when and where a > process drops off. > > Many times, the relationship between publisher and subscriber is more > or less 1-to-1. For a given message, there is 1 publisher and exactly > 1 subscriber. Much complexity introduced for anticipated flexibility > that is never used. > > I see this pattern repeated in many places, hence my position on > pub/sub. To me, pub/sub seems generally misused and misapplied. > > This is not intended as an indictment of all intermediated > interactions, nor a claim that pub/sub is a Bad Thing in all cases. I > just think pub/sub is used more than it should be. > > Of course YMMV. :-) > > -Rob > > --- In > [email protected]<service-orientated-architecture%40yahoogroups.com>, > "Udi Dahan" > <[EMAIL PROTECTED]> wrote: > > > > I've put a short article up on my blog about the whole issue of lost > > notifications and pub/sub. > > > > > > > > Lost <http://www.udidahan.com/2008/12/07/lost-notifications-no- > > problem/> Notifications? No Problem. > > > > In it I outline how the various performance and availability > > characteristics of different services may cause a subscriber to > > miss a notification and how to feed that back into the design > > process to get a service ecosystem where notifications (different > > kinds than before) won't be lost or missed. > > > > Interested in hearing feedback, especially on how this may impact > > the issues of monitoring and management Rob raised below. > > > > > > > > -- > > > > Udi Dahan - The Software Simplist > > >
