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From David Jencks <da...@coredevelopers.net>
Subject Re: cvs commit: incubator-geronimo/modules/core/src/java/org/apache/geronimo/naming/java ReadOnlyContext.java
Date Tue, 09 Dec 2003 20:22:48 GMT

On Tuesday, December 9, 2003, at 10:40 AM, David Blevins wrote:

> On Mon, Dec 08, 2003 at 09:43:39PM -0800, David Jencks wrote:
>> I'm sorry, I don't understand all about jndi.
>>
>> Could you give an example of what this is for, and how it differs from
>> binding into the read only context refs whose targets are in say the
>> jmx context?
>
> The ReadOnlyContext is used by the OpenEJB nova containers, so there 
> is no jmx anything going on.

At least when deployed in geronimo, ejb-refs, ejb-links, and 
resource-refs are done by binding a reference into the jmx jndi 
context.  A name in this context essentially is an object name + 
operation name, and the the lookup is done by returning the result of 
the operation.

>  The situation is that I need to add another Context implementation, 
> one built by OpenEJB, into the ReadOnlyContext of an EJBContainer.
>
> Doing this by instantiating the ReadOnlyContext with a Map, where one 
> of the values is the non-ReadOnlyContext context object.  Lookups to 
> the respective name need to be delegated to that context object.

Would you get the same effect by listing the OpenEJB context and 
binding everything you found into the ReadOnly context?
>
>> Does this have the effect of making the ReadOnlyContext mutable, in
>> that you can look up whatever happens to be currently bound in the
>> subcontext?
>
> It could if the Context added allowed bind operations, but in this 
> case it doesn't.  The neat thing is that the "outside" context is only 
> checked if the lookup failed against the ReadOnlyContext, so 
> everything in the ReadOnlyContext essentially trumps the outside 
> context.  This is useful for the UserTransaction object.

So, is a typical name you might look up something like
java:/comp/env/geronimo/read/only/openejb/context/actualobject

where the "context shift" occurs between 'only' and 'openejb'?

And... If I write some kind of mutable context, that say looked up 
connection factories in jmx based on knowing most of their object name 
and the operation to use, I could bind this into the ReadOnlyContext?

many thanks
david jencks

>
> -David Blevins
>
>>
>> Thanks
>> david jencks
>>
>> On Monday, December 8, 2003, at 09:03 PM, dblevins@apache.org wrote:
>>
>>> dblevins    2003/12/08 21:03:49
>>>
>>>  Modified:    modules/core/src/java/org/apache/geronimo/naming/java
>>>                        ReadOnlyContext.java
>>>  Log:
>>>  Added support to do lookups from other Context implementations.  In
>>> other words,
>>>  sub-contexts under the context which aren't ReadOnlyContext
>>> implementations.
>>>
>>>  Revision  Changes    Path
>>>  1.7       +23 -3
>>> incubator-geronimo/modules/core/src/java/org/apache/geronimo/naming/
>>> java/ReadOnlyContext.java
>>>
>>>  Index: ReadOnlyContext.java
>>>  ===================================================================
>>>  RCS file:
>>> /home/cvs/incubator-geronimo/modules/core/src/java/org/apache/
>>> geronimo/naming/java/ReadOnlyContext.java,v
>>>  retrieving revision 1.6
>>>  retrieving revision 1.7
>>>  diff -u -r1.6 -r1.7
>>>  --- ReadOnlyContext.java	16 Nov 2003 05:24:38 -0000	1.6
>>>  +++ ReadOnlyContext.java	9 Dec 2003 05:03:49 -0000	1.7
>>>  @@ -87,7 +87,7 @@
>>>    * resolution phase performed by the JVM takes considerably longer,
>>> so for
>>>    * optimum performance lookups should be coded like:</p>
>>>    * <code>
>>>  - *   Context componentContext = new
>>> InitialContext().lookup("java:comp");
>>>  + *   Context componentContext = (Context)new
>>> InitialContext().lookup("java:comp");
>>>    *   String envEntry = (String)
>>> componentContext.lookup("env/myEntry");
>>>    *   String envEntry2 = (String)
>>> componentContext.lookup("env/myEntry2");
>>>    * </code>
>>>  @@ -122,7 +122,11 @@
>>>       }
>>>
>>>       ReadOnlyContext(Hashtable env) {
>>>  +        if (env == null) {
>>>  +            this.env = new Hashtable();
>>>  +        } else {
>>>           this.env = new Hashtable(env);
>>>  +        }
>>>           this.bindings = Collections.EMPTY_MAP;
>>>           this.treeBindings = Collections.EMPTY_MAP;
>>>       }
>>>  @@ -159,8 +163,24 @@
>>>                       throw new NamingException("scheme " + scheme +
>>> " not recognized");
>>>                   }
>>>                   return ctx.lookup(name);
>>>  +            } else {
>>>  +                // Split out the first name of the path
>>>  +                // and look for it in the bindings map.
>>>  +                CompositeName path = new CompositeName(name);
>>>  +
>>>  +                if (path.size() == 0) {
>>>  +                    return this;
>>>  +                } else {
>>>  +                    Object obj = bindings.get(path.get(0));
>>>  +                    if (obj == null){
>>>  +                        throw new NameNotFoundException(name);
>>>  +                    } else if (obj instanceof Context &&
>>> path.size() > 1){
>>>  +                        Context subContext = (Context) obj;
>>>  +                        obj = subContext.lookup(path.getSuffix(1));
>>>  +                    }
>>>  +                    return obj;
>>>  +                }
>>>               }
>>>  -            throw new NameNotFoundException(name);
>>>           }
>>>           if (result instanceof LinkRef) {
>>>               LinkRef ref = (LinkRef) result;
>>>
>>>
>>>
>>>
>


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