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From "Krishnakumar B" <www....@gmail.com>
Subject Re: Implementing Global JNDI
Date Fri, 23 Jun 2006 14:42:13 GMT
hi,

We ( Me & Manu )  have created a implementation of global JNDI based
on the feedback received on the dev list.

It works like this.

* The implementation uses GeronimoRootContext and ReadOnlyContext
thats part of naming module to create the root context ( geronimo: ).
The  Context is accessed by means of a Factory
GeronimoInitialContextFactory that implements InitialContextFactory.

* A GBean ( GeronimoContextGBean ) loads on start of server and
creates the Root Context.  Now applications can bind to this context.

* We have added GBeans to naming ( GlobalJNDIBindingGBean for RA,
DataSource, QCF/TCF,Queue, Topic  and EJBJNDIBindingGBean for EJB )
that are deployed when an app is deployed.

* The builders add the Gbeans during the deployment process. [
ConnectorModule Builder, OpenEJBModuleBuilder, ServiceConfigBuilder ].

The plan needs to have some XML Tag to say this resource needs to gets
into Global JNDI and the builder can then add it to geronimo: Context.
This is not implemented yet. Currently if we deploy a connector it
gets in global jndi.

The current code we can add DataSource, RA, EJB, QCF, Queue/Topic,
GBeans to geronimo: Context. With some changes to context
implementation any object can be bound to global JNDI. ( Have not
looked at security aspect and would need some ideas on how to proceed
).

This may need some more work and changes before it takes final form to
get into product. Kindly provide your review, comments and
contributions from others who are interested and have better ideas.

We are not able to attach the code as mailing list rejects attachments.

Regards
Krishnakumar B


On 5/24/06, Krishnakumar B <www.bkk@gmail.com> wrote:
> Thanks for the feedback and inputs.
>
> Regards
> Krishnakumar
>
>
> On 5/24/06, Dain Sundstrom <dain@iq80.com> wrote:
> > On May 23, 2006, at 5:19 PM, David Jencks wrote:
> >
> > >
> > > On May 23, 2006, at 6:28 AM, Krishnakumar B wrote:
> > >
> > >> Hi,
> > >>
> > >> I have a few doubts related to implementation of global jndi.
> > >>
> > >> * Currently we have java:comp/env stored in Local JNDI. In Global
> > >> JNDI
> > >> should objects be bound using a different namespace e.g) java: or
> > >> java:global?
> > >
> > > IIUC java: is reserved by the j2ee spec for what it requires: thus
> > > IMO we should use something else.  IIRC the original global jndi
> > > context used geronimo:  I'm OK with that or maybe global:.
> >
> > IIRC some servers use just "/foo/bar" with no context.  If I am
> > correct, we should support that also (but not the default).
> >
> > >>
> > >> * When we implement global JNDI we have some entries in Global and
> > >> All
> > >> entries related to application in Local. When a user creates a
> > >> context
> > >> he needs to get from either global or local based on what he needs.
> > >> Would it be right for lookup code to decide from where to fetch the
> > >> entry based on how the Context is created?
> > >>
> > >> for e.g) if i say InitialContext iniCtx = new
> > >> InitialContext("java:comp/env"); fetch from local
> > >> and if InitialContext iniCtx = new InitialContext("java:global");
> > >> fetch from global
> > >
> > > I'm not sure what you're asking about here.  Unless you do
> > > something screwy to link one of these to the other, the contents of
> > > these contexts will be completely unrelated.
> >
> > Looking at the JavaDocs for InitialContext, it does not have a
> > constructor that takes a String.  Did you mean:
> >
> >   Context context = (Context) new InitialContext().lookup("java:comp/
> > env");
> >   Context context = (Context) new InitialContext().lookup("global:");
> >
> > >> * Currently in Local JNDI we store Resource References. Should global
> > >> JNDI also use the same approach or can we use Object references for
> > >> e.g) DataSource reference directly put in JNDI
> > >
> > > For j2ee components I think we should bind the same kinds of
> > > References in the global jndi tree as we bind in the current java:
> > > context.  What we bind for stuff that can't get into the java:
> > > context needs more thought: it probably depends on what it is.  Of
> > > course if the context is not read-only an app can bind whatever it
> > > wants wherever it wants, thus bringing to mind the need for
> > > security and permissions for this stuff.
> >
> > I don't think we can use the current Reference object we bind into
> > our read only context because they do cache the value and never
> > release it.  It is expected that the referece will be GCed when the
> > J2EE application is unloaded.  It shouldn't be hard to either turn
> > off the cache or to register listener for the reference target life-
> > cycle events.
> >
> > >> Would appreciate any thoughts as i am still learning and might have
> > >> missed some points to consider while trying to implement something
> > >> like this.
> > >
> > > My plan for implementing this was:
> > >
> > > 1. Look at the current ReadOnlyContext implementation and figure
> > > out how to make a sufficiently synchronized version of it.  I'm
> > > hoping that we can have synchronized wrappers around this
> > > implementation rather than needing a copy, subclass, or new
> > > implementation.
> >
> > I think a read only JNDI and a mutable one are different enough that
> > they need separate implementations.  Currently our ENC is using a the
> > EnterpriseNamingContext which does not extend ReadOnlyContext (as it
> > isn't really read only).  I'd like to keep the
> > EnterpriseNamingContext simple and strictly read only.  Therefore,
> > I'd like to see an new separate implementation.  If I were going to
> > write it, I'd base it on ConcurrentReaderHashMap and future objects
> > in Java5 (or backport-concurrent-util), but I'm not writing it, so I
> > say do whatever you are comfortable with.
> >
> > > 2. Remind myself of how the geronimo: context used to be
> > > installed.  I think the same method will still work.  We might want
> > > a gbean to specifically install it.  Make sure that programmatic
> > > binding and lookup works.
> >
> > IIRC, we add set naming provider package to
> > org.apache.geronimo.naming and when a user tries to access the "foo:"
> > root-context, the jvm looks for the class
> > org.apache.geronimo.naming.foo.fooURLContextFactory.  We still have
> > one named global that most likely gets loaded when someone looks up
> > "global:"
> >
> > > 3. Figure out how to bind stuff into this context from plans rather
> > > than java code.  Currently my idea is to do this with binding
> > > gbeans: I'm not entirely sure how to do this but one possibility
> > > would be to have them contain a Reference object and the name to
> > > bind it under.  Another possibility would be to not use References
> > > but rather have a binding gbean with say a gbean  reference to a
> > > ManagedConnectionFactoryWrapper: the gbean would call $getResource
> > > () on it and then bind the result directly into jndi.  This would
> > > result in simpler builders but more gbeans: we'd need one for
> > > resource-refs and resource-env-refs, and another one for ejbs, and
> > > another for plain gbean bindings.  One thing I like about this
> > > second plan is that  the object would only be bound in jndi while
> > > the resource was actually available.  Of course, the component that
> > > looks up the entry can still keep it until the underlying gbean
> > > support is long gone, and get exceptions when it tries to use the
> > > entry.
> >
> > I think binding will be the hardest part :)
> >
> > -dain
> >
>

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