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From "David Illsley" <davidills...@gmail.com>
Subject Re: [axis2] Improvements to Service life cycle in handling -setOperationContext not thread-safe??!!
Date Tue, 10 Oct 2006 19:21:18 GMT
In terms of setting up TLS info, I'm interested by the comment that it
would be set in the AxisEngine. When we had the conversation about the
ThreadContextMigrator interface (which does now exist) I understood
that there wasn't any guarantee that there is a single thread in use
through the handler chain.

Was this a misunderstanding or is this a change?
David

On 10/10/06, Tom Jordahl <tjordahl@adobe.com> wrote:
>
> While we may have had to work around some bugs in Thread Local Storage
> (TLS) on the whole I think the Axis 1.x
> MessageContext.getCurrentContext() works exceptionally well.
>
> Since JDK 1.4 is the minimum for Axis2, I believe we have all the TLS
> bugs behind us, no?
>
>
> --
> Tom Jordahl
> Adobe ColdFusion Team
>
> -----Original Message-----
> From: Sanjiva Weerawarana [mailto:sanjiva@opensource.lk]
> Sent: Tuesday, October 10, 2006 10:28 AM
> To: dims@apache.org
> Cc: axis-dev@ws.apache.org
> Subject: Re: [axis2] Improvements to Service life cycle in handling
> -setOperationContext not thread-safe??!!
>
> Other choices?
>
> The approach we used back in ApacheSOAP was to tell the user to add an
> additional first parameter to their methods if they wanted the
> context .. so the signature would have an additional param and that'd
> tell us to do the right thing. Very thread safe.
>
> Need to avoid reflection - but can be done by a codegen flag. For RPC
> case its reflective anyway so its not a big deal.
>
> Sanjiva.
>
> On Tue, 2006-10-10 at 09:40 -0400, Davanum Srinivas wrote:
> > Sanjiva,
> >
> > We had terrible problems with TLS in Axis1...let me recollect my
> > thougts and post.
> >
> > -- dims
> >
> > On 10/10/06, Sanjiva Weerawarana <sanjiva@opensource.lk> wrote:
> > > I think I agree with you. How about we drop setOperationContext()
> and
> > > introduce Axis1-style MessageContext.getCurrentContext() which
> returns
> > > it for this thread? Have to be careful to put it in TLS and take it
> off!
> > >
> > > We must be careful to tell users that instance variables are not
> > > supported; you have to use MessageContext properties to store state
> (or
> > > wherever else).
> > >
> > > Sanjiva.
> > >
> > > On Sun, 2006-09-24 at 14:12 +0200, Christopher Sahnwaldt wrote:
> > > > Entered as http://issues.apache.org/jira/browse/AXIS2-1224 .
> > > > I set the priority to blocker as David suggested.
> > > >
> > > > IMHO it's probably best to drop the method. Many users will use it
> in an
> > > > intuitive but wrong way. The only way to store the data it
> provides is an
> > > > instance variable, and telling users to either use only request
> scope or use
> > > > a ThreadLocal to store the data does not seem to be compatible
> with the
> > > > rule of least surprise. Something like
> MessageContext.getCurrentContext()
> > > > in Axis 1 might be better.
> > > >
> > > > Bye,
> > > > Christopher.
> > > >
> > > > Davanum Srinivas wrote:
> > > > > Chris,
> > > > >
> > > > > Can you please raise a new issue in JIRA?
> > > > >
> > > > > thanks,
> > > > > dims
> > > > >
> > > > > On 9/23/06, Christopher Sahnwaldt <chrisahn@gmx.net> wrote:
> > > > >> Something worries me:
> > > > >>
> > > > >> > setOperationContext(OperationContext) - per call.  The
> messageContext
> > > > >> > can be obtained to gain per call instance information.
> > > > >>
> > > > >> That doesn't seem to be thread-safe, does it? If I understand
> this
> > > > >> correctly, one service object is created per application (if
> the
> > > > >> service has application scope). When a request comes in, Axis
> calls
> > > > >> the setOperationContext method, and the service object may
> store the
> > > > >> OperationContext or the MessageContext. Then Axis calls the
> actual
> > > > >> service method, in which the service code can access the stored
> > > > >> OperationContext or MessageContext. But what if two requests
> come
> > > > >> in almost simultaneously? The following sequence of method
> calls
> > > > >> may occur:
> > > > >>
> > > > >> - Axis calls setOperationContext with context for request A,
> the
> > > > >>   service object stores the context in an instance field.
> > > > >> - Axis calls setOperationContext with context for request B,
> the same
> > > > >>   service object stores the context in the same instance field
> and
> > > > >>   thus *overwrites* the context for call A.
> > > > >> - Axis calls the service method with the input parameters for
> request A.
> > > > >> - The service method processes the call, using data from the
> stored
> > > > >>   context, and thus *mixes the input parameters for call A with
> the
> > > > >>   context data for call B*. Anything can happen...
> > > > >> - Finally, Axis calls the service method with the input
> parameters
> > > > >>   for call B, the service method processes the call, using data
> from
> > > > >>   the stored context, and thus correctly uses the input
> parameters
> > > > >>   for call B with the context data for call B. Probably ok,
> unless
> > > > >>   the service method updated the context in some way during the
> call
> > > > >>   for request A.
> > > > >>
> > > > >> But I hope I'm wrong or misunderstood or forgot something...
> ;-)
> > > > >>
> > > > >> Axis 1 avoided this problem by
> MessageContext.getCurrentContext(),
> > > > >> which gives access to the MessageContext *for the current
> thread*
> > > > >> from within any service method, without the need for a
> > > > >> setMessageContext (or setOperationContext) method on the
> service
> > > > >> object.
> > > > >>
> > > > >> Bye,
> > > > >> Christopher.
> > > > >>
> > > > >>
> > > > >> Tony Dean wrote:
> > > > >>
> > > > >> > Can we fully document the logical semantics behind each
> method?
> > > > >> >
> > > > >> > init(ServiceContext) - To me this use to mean application
> init.
> > > > >> Now it means session init.  However, when running
> > > > >> scope="Application", it is analogous to application init since
> you
> > > > >> will only have one session;  but, still probably not
> appropriate to
> > > > >> think in those terms.
> > > > >> >
> > > > >> > How should an application use this method?  A session
> use-case
> > > > >> would be nice.
> > > > >> >
> > > > >> > destroy(ServiceContext) - inverse of init()
> > > > >> > Use-case?
> > > > >> >
> > > > >> > setOperationContext(OperationContext) - per call.  The
> > > > >> messageContext can be obtained to gain per call instance
> information.
> > > > >> >
> > > > >> > StartUp() - one time initialization... DB connections etc...
> > > > >> > Shutdown() - inverse of StartUp()
> > > > >> >
> > > > >> > Any more insight or corrections to pattern usage would be
> grateful...
> > > > >> >
> > > > >> > Thanks.
> > > > >> >
> > > > >> > -----Original Message-----
> > > > >> > From: robert lazarski [mailto:robertlazarski@gmail.com]
> > > > >> > Sent: Friday, September 15, 2006 8:49 AM
> > > > >> > To: axis-dev@ws.apache.org
> > > > >> > Subject: Re: Improvements to Service life cycle in handling
> > > > >> >
> > > > >> > That makes sense to me. I've been using startUp() and it
> doesn't
> > > > >> really fit with the other methods of the interface in its
> current
> > > > >> form. +1 for 1.1 since its interface changes and it'd be better
> to do
> > > > >> it now.
> > > > >> >
> > > > >> > One question: Currently you need this in services.xml to
get
> > > > >> startUp() to invoke:
> > > > >> >
> > > > >> > <parameter name="load-on-startup"
> locked="false">true</parameter>
> > > > >> >
> > > > >> > I plan on testing this when its ready ... since the spring
> tutorial
> > > > >> depends on it ... so I thought I'd ask if the services.xml
> param will
> > > > >> remain the same.
> > > > >> >
> > > > >> > Thanks,
> > > > >> > Robert
> > > > >> >
> > > > >> > On 9/14/06, Deepal Jayasinghe <deepal@opensource.lk>
wrote:
> > > > >> >
> > > > >> >> Hi All;
> > > > >> >>
> > > > >> >> Currently we have an interface called Service and which
has
> few
> > > > >> >> methods that are used to manage session (or else user
can
> add those
> > > > >> >> method into service impl class w.o implementing the
> interface). And
> > > > >> >> that interface has the following methods ;
> > > > >> >>
> > > > >> >> - startUp
> > > > >> >> - init
> > > > >> >> - setOperationContext
> > > > >> >> - destroy
> > > > >> >>
> > > > >> >> Three of them are for managing service life cycle ;
> > > > >> >> - init - will be called when the session start
> > > > >> >> - setOperationContext - immediately before calling actual
> java method
> > > > >> >> - destroy - will be call when the session finishes
> > > > >> >>
> > > > >> >> Remember all those method work if and only if you use
Axis2
> default
> > > > >> >> message receiver or you code gen.
> > > > >> >>
> > > > >> >> The method startUp is not session related method , which
is
> useful
> > > > >> >> when you want to initialize database connections , create
> thread etc
> > > > >> >> ... at the time when you deploy the service. In the
mean
> time
> > > > >> >> interface name Service is bit confusing to me AFAIK
it
> should be
> > > > >> >> ServiceLifeCycle. And having method like startUp in
that
> interface
> > > > >> confuses the users.
> > > > >> >>
> > > > >> >> So how about the following changes ;
> > > > >> >> - Rename Service interface into ServiceLifeCycle
> > > > >> >> - Then remove startUp method from that interface.
> > > > >> >>
> > > > >> >> There should be a some other interface (like Module
> interface) and
> > > > >> >> which should be optional as well , to have the method
> startUp. If
> > > > >> >> someone want to open DB connection or anything at the
time
> of service
> > > > >> >> deploying , then he need to implement that interface
(and
> for me
> > > > >> which
> > > > >> >> is identical to Module interface). So with this change
> service
> > > > >> element
> > > > >> >> inside the services.xml will be change to following
> > > > >> >>
> > > > >> >> <service name="foo" *class="implementation class
of the
> interface "*>
> > > > >> >> <parameter name="ServiceClass">ServiceClass</parameter>
> > > > >> >> </service>
> > > > >> >>
> > > > >> >> Here the class attribute is optional , so if someone
want to
> have
> > > > >> >> loadonStartup feature then he need to implement the
Service
> interface
> > > > >> >> (new one) and put the impl name as the class attribute.
This
> is very
> > > > >> >> useful if your service implementation class is not java
(if
> you are
> > > > >> >> writing a groovy serice).
> > > > >> >>
> > > > >> >> So new Service interface will be look like follows;
public
> interface
> > > > >> >> Service{ //will be called when service is deployed public
> void
> > > > >> >> startUp(ConfigurationContext configctx, AxisService
> service); //will
> > > > >> >> be called when Axis2 server showdown or when service
removed
> from the
> > > > >> >> system public void shutDown(ConfigurationContext configctx,
> > > > >> >> AxisService service); }
> > > > >> >>
> > > > >> >> And ServiceLifeCycle interface will look like below;
> > > > >> >>
> > > > >> >> public interface ServiceLifeCycle {
> > > > >> >> public void init(ServiceContext sc);
> > > > >> >> public void setOperationContext(OperationContext
> operationContext);
> > > > >> >> void destroy(ServiceContext sc); }
> > > > >> >>
> > > > >> >>
> > > > >> >> I am +1 on doing this for Axis2 1.1 :)
> > > > >> >>
> > > > >> >> Suggestions ........
> > > > >> >>
> > > > >> >> Thanks
> > > > >> >> Deepal
> > > > >> >>
> > > > >> >>
> > > > >> >>
> > > > >> >>
> ---------------------------------------------------------------------
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> > > > >> >>
> > > > >> >>
> > > > >> >>
> > > > >> >
> > > > >> >
> ---------------------------------------------------------------------
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> > > > >> >
> > > > >> >
> > > > >> >
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> > > > >> >
> > > > >>
> > > > >>
> > > > >>
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> > > > >>
> > > > >>
> > > > >
> > > > >
> > > >
> > > >
> > > >
> ---------------------------------------------------------------------
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> > > >
> > >
> > >
> > >
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> > >
> > >
> >
> >
>
>
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>


-- 
David Illsley - IBM Web Services Development

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