:-) I enjoy getting the credit for Brian's work. David
On 07/03/07, Sanjiva Weerawarana <[EMAIL PROTECTED]> wrote:
Thanks David! Definitely +1 for fixing this in Sandesha .. Sanjiva. Brian De Pradine wrote: > > Hi Sanjiva, > > If this problem can be fixed in the Sandesha layer that will be better > than the current fix. I will revert the changes. > > Cheers > > Brian DePradine > Web Services Development > IBM Hursley > External +44 (0) 1962 816319 Internal 246319 > > If you can't find the time to do it right the first time, where will you > find the time to do it again? > > > Sanjiva Weerawarana <[EMAIL PROTECTED]> wrote on 05/03/2007 02:59:15: > > > Brian De Pradine wrote: > > > > > > In this scenario the server sends a response message to the client. > The > > > client then tries to send an acknowledgement to the server, but the > > > acknowledgement gets lost, for whatever reason. This means that the > > > WS-RM layer, in the server, will eventually time-out and send the > > > response message again. This time the client should send an > > > acknowledgement to cover both the original and the duplicate response > > > messages. > > > > > > This scenario is broken because the duplicate response never makes > it to > > > the WS-RM layer on the client side, because the > > > AddressingBasedDispatcher recognises it as a duplicate and throws an > > > exception instead. This means that the WS-RM layer never gets > driven to > > > send the second acknowledgement. The result is that the server will > > > simply keep sending duplicate responses forever (almost)! > > > > > > In order to get this scenario to work the AddressingBasedDispatcher > will > > > need to dispatch any duplicate messages as normal, instead of deciding > > > that they are 'bad' and throwing an exception. This will allow > WS-RM to > > > be easily added into the picture at any time. This also means that if > > > there is no WS-RM engaged then a service will potentially be driven > more > > > than once if there are duplicate messages (created by some other > means). > > > This shouldn't be a problem, however, because web services are > meant to > > > be stateless entities anyway :-) If you do happen to have a web > service > > > that is not stateless then you will need to engage WS-RM to ensure > that > > > it is not driven by duplicates. > > > > OK I understand the scenario but I'm -1 on this because it breaks normal > > users. You can't say that Web services are stateless and therefore > its ok > > to just let messages get delivered repeatedly violating our MEP concept! > > > > RM is a lower level thing than MEPS- its infrastructural. The MEP should > > not be marked complete if the message hasn't been received to the > > satisfaction of the lower level. > > > > If what Chamikara suggests will fix this for RM that's great but no > matter > > what this change is not acceptable because its breaking the > definition of > > a MEP. Think of a TCP analogy: TCP users a protocol similar to RM to > > resend packets. Anyone who implements something like HTTP over TCP > doesn't > > need to be concerned with the response being delivered twice!! > > > > Sanjiva. > > -- > > Sanjiva Weerawarana, Ph.D. > > Founder & Director; Lanka Software Foundation; http://www.opensource.lk/ > > Founder, Chairman & CEO; WSO2, Inc.; http://www.wso2.com/ > > Director; Open Source Initiative; http://www.opensource.org/ > > Member; Apache Software Foundation; http://www.apache.org/ > > Visiting Lecturer; University of Moratuwa; http://www.cse.mrt.ac.lk/ > > > > > > --------------------------------------------------------------------- > > To unsubscribe, e-mail: [EMAIL PROTECTED] > > For additional commands, e-mail: [EMAIL PROTECTED] > > > > > > ------------------------------------------------------------------------ > > / > / > > /Unless stated otherwise above: > IBM United Kingdom Limited - Registered in England and Wales with number > 741598. > Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU/ > > > > > > -- Sanjiva Weerawarana, Ph.D. Founder & Director; Lanka Software Foundation; http://www.opensource.lk/ Founder, Chairman & CEO; WSO2, Inc.; http://www.wso2.com/ Director; Open Source Initiative; http://www.opensource.org/ Member; Apache Software Foundation; http://www.apache.org/ Visiting Lecturer; University of Moratuwa; http://www.cse.mrt.ac.lk/ --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
-- David Illsley - IBM Web Services Development --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
