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From Srinath Perera <hemap...@gmail.com>
Subject Re: [Axis2] Thoughts on making Session Model independent of the InformationModel [Ctx Heirachy]
Date Tue, 31 Jan 2006 10:57:37 GMT
Thanks Paul, Rajith .. got the point.

One more Q? when we cluster Axis2, should be distribute (at least
somepart of)  information model.  Distributed deployment means more or
less distributed information Model IMHO

Thanks
Srinath

On 1/31/06, Paul Fremantle <pzfreo@gmail.com> wrote:
> Rajith
>
> +1
>
> I think the main aspect is simply this:
>
> If we have a cluster of Axis2, I can get my request directed to any server
> in the cluster. The standard context is the same on each machine, because
> the configuration, etc should be the same. But the session data is specific
> to my interaction, and must be moved from machine to machine. Without making
> this simple, standalone and lightweight we cannot cluster a session based
> interaction.
>
> Paul
>
>
> On 1/30/06, Rajith Attapattu <rajith77@gmail.com> wrote:
> >
> > Srinath,
> >
> > Let me explain a bit more behind my thinking.
> >
> > When you look at clustering sessions we need to have a clear abstraction
> of a session and session manager and it has to be light weight.
> >
> > This gives you the following flexibility.
> >
> > a) if it's not deployed in clustered mode then you run install a
> LocalSessionManager (could be the default)
> >
> > b) if it's deployed in clustered mode then you install a
> RemoteSessionManager
> >
> > c) if u need to persist the session (for failover and recovery) then u
> need to decorate a SessionManager with a PersistantSessionManager
> >
> > d) Your base remote session manager can be decorated to use JGroups or
> WADI or ActiveCluster to use as the remoting platform
> >
> > e) You can decorate your base  PersistantSessionManager to be DB backed or
> file backed..etc
> >
> > None of the above is possible with the Information model. It's very rigid
> and definitely not light weight.
> > the information model is designed for a different purpose.
> >
> > Look at other projects (for ex Geronimo) they also have a light weight
> session model thats independent of any other mechanism.
> >
> > Frankly I don't know how the clustering will work if it's tied to the
> information model, besides it will complecated to wire in the clustering
> code to the information model.
> >
> > Why not keep it simple, a handler can did in the sesion and inject it to
> the message context.
> >
> > I agree that information model is to manage information (but I argue that
> it should be limited to manage service specific information)
> >
> > Remember a session can be far beyond the scope of a single axis2 instance.
> A session can span across multiple nodes or even multiple clusters. A
> session can exist between an Axis2 instance and a .Net System or some other
> SOAP stack. Look at the following use case
> >
> >
> > Client -------> (Accounting system [Runs on Axis2])  ------ (may have to
> acess the payroll system) --------> (Payroll system [Runs on XFire] )
> >
> > (I know we don't support this now (maybe in the future with WS-Context)
> !!! )
> >
> > Lets say the client requets to print Monthly account and it has to get
> some information from the Payroll system
> > In such a situation we can't ask the client to reauthenticate with the
> payroll system. As far as the client is concerned it's a single session for
> him, doesn't care wether it spans several systems as long as it's
> transparent to the client.
> >
> > Regards,
> >
> > Rajith.
> >
> >
> >
> > On 1/30/06, Srinath Perera <hemapani@gmail.com > wrote:
> > > Hi Rajith;
> > >
> > > Information model is for manging the information .. (with there
> > > scopes). Session should be part information model.
> > >
> > > You need something with global scope to store the map that cantains
> > > session, that should be part of information model
> > >
> > > Thanks
> > > Srinath
> > >
> > > On 1/27/06, Rajith Attapattu < rajith77@gmail.com> wrote:
> > > >
> > > >  Hi Guys,
> > > >
> > > >  What are your thoughts on making the Session Model independent of the
> > > > Information Model or more specifically the Context Heirachy.
> > > >
> > > >  1. If we sperate the two areas then both models can evolve
> independently of
> > > > each other without limiting the growth of each other.
> > > >
> > > > 2. From a scalability point of view I don't think it's good idea to
> couple
> > > > the "session" with the context heirachy.
> > > >
> > > > 3. Currently there is no clearly boundries wrt to where the scope
> begings or
> > > > ends with ServiceGroupContext and ServiceGroup. I got mixed answers
> about
> > > > the usage and usefulness of these.
> > > >
> > > > Let me quote from one of email to the Session mgt proposal thread.
> > > >
> > > >
> > > > a) The Session model should be lightweight and clearly defined with
> proper
> > > > boundries.
> > > >
> > > > b) It should not be tied to any other model as it might be
> architecurally
> > > > unstable as there want be a clear demarcation point.
> > > >
> > > > c) when things start to move across the wire (Session replication)
> having a
> > > > clean, well defined session model is very very important.
> > > >
> > > > Right now the most critical shortcomming of Axis2 as I understand is
> that we
> > > > don't have a clear picture of what a session is wrt to the current
> Axis2
> > > > architecture.
> > > > I gues Srinath mentioned that same thing to me.
> > > >
> > > > My suggestion is we should evolve the Session Model independently of
> > > > anything else and inject it to the ServiceAuthor via the message
> context by
> > > > way of a handler.
> > > >
> > > > If we do that we want have any limitation or complications of
> associating it
> > > > with ServiceGroups or anything like that.
> > > >
> > > >
> > > > What do u guys think???
> > > >
> > > > Regards,
> > > >
> > > > Rajith.
> > >
> > >
> > > --
> > > ============================
> > > Srinath Perera:
> > >    http://www.cs.indiana.edu/~hperera/
> > >    http://www.bloglines.com/blog/hemapani
> > >
> >
> >
>
>
>
> --
> Paul Fremantle
> VP/Technology, WSO2 and OASIS WS-RX TC Co-chair
>
> http://bloglines.com/blog/paulfremantle
> paul@wso2.com
>
> "Oxygenating the Web Service Platform", www.wso2.com
>


--
============================
Srinath Perera:
   http://www.cs.indiana.edu/~hperera/
   http://www.bloglines.com/blog/hemapani

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