Essential Components
A basic service provider has the following necessary components.
- Context implementation. A class that implements the
Context
interface or one of its subinterfaces.
This implementation is the guts of the provider. It is responsible
for handling almost all of the requests submitted by the user application.
- Initial context factory. A class that implements the
InitialContextFactory interface.
This factory creates the root
context that will satisfy method invocations on the
InitialContext or its subclasses.
The root context that is created by the initial context factory
is typically an instance of the context implementation.
- Name parser. A class that implements the
NameParser interface.
The context implementation uses this parser to parse
names that belong to its namespace.
The following picture illustrates
how these three components interact.
The arrows indicate instantiation paths.
Adding Extensibility
To make a context implementation extensible, you should use
methods provided by the JNDI SPI framework.
These methods are described in detail in the
The Essential Pieces 
lesson.
They use the
object,
state, and
response control factories
accessible to the application.
These factories might be packaged with the service provider or
be supplied by the application.
The following picture depicts how a basic service provider interacts
with these factories.
