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
