This section describes additional miscellaneous issues that a
context implementation must handle.
Resource Management
The Java programming language provides automatic garbage collection.
This means that when an object is no longer being referenced, the Java
runtime will automatically dispose of it.
close()
gives the API user a way to dispose of a Context instance and
its associated resources before automatic garbage collection kicks in.
This is important for network-based context implementations because
network connections are a limited resource for both clients and servers.
The flat namespace example does not provide any
substantial implementation for close().
An actual implementation, especially one that must manage network connections,
would define close() to clean up references and connections.
Environment Properties
The Ground Rules 
lesson describes how a context implementation should treat its environment
properties.
Even though
the flat namespace
and
hierarchical namespace
examples don't use any environment properties,
they must provide implementations for the environment-related methods.
As suggested by the
The Ground Rules lesson,
getEnvironment() should provide a read-only copy or a clone of its environment properties to
its caller.
addToEnvironment() and
removeFromEnvironment() are used by a program to update a context's environment.
The flat namespace example simply updates its internal
environment hash table. An actual implementation would examine the
property name and act appropriately to update the
Context instance's behavior accordingly.
Unsupported Operations
A context implementation must provide a valid implementation for
lookup().
For all other methods,
if a context implementation does not support a particular method,
then the method definition should throw an
OperationNotSupportedException.
For example, a context implementation for a read-only underlying naming service
cannot support any methods that involve updates.
Here is an example of such a context
implementation's definition of
Context.bind().
public void bind(Name obj, Object obj) throws NamingException {
throw new OperationNotSupportedException(
"Read-only service does not support updates");
}
