Java Reference
In-Depth Information
Table 7-1. Packages and corresponding use
Package Use
javax.naming
Provides the basic JNDI framework.
javax.naming.directory
Provides extensions for directory services.
javax.naming.event
Provides extensions for event handling.
javax.naming.ldap
Provides extensions to support LDAP v.3.
javax.naming.spi
Service-provider interface. It's the core model that is extended to provide an
underlying service that JNDI uses.
Pattern Use
The following patterns are features of certain kinds of JNDI resources:
Factory Method
(see page 21): The Factory Method pattern provides a standard method to create some product,
so this pattern is typically encountered for any JNDI resource that is capable of producing a connection. This
pattern is typically encountered for any JNDI resource capable of producing a connection. One of the best
illustrations is the JDBC
DataSource
, often stored in JNDI as part of a J2EE solution. The
DataSource
class is
actually a Factory for
Connection
objects enabling clients to communicate with a RDBMS.
Factory patterns are very much in evidence in the service provider interface. Underlying service implementations
that are paired with JNDI require factories so that API calls can be paired to implementations that map to the
underlying service structure. The
DirObjectFactory
,
DirStateFactory
,
InitialContextFactory
,
ObjectFactory
, and
StateFactory
all provide Factory Method implementations that subsequently produce
concrete products which are associated with specific kinds of services.
HOPP
(see page 189): Many distributed communication technologies can support division of functionality
between local and remote objects, so it's no surprise that RMI, CORBA and EJB technologies are all capable of
supporting a HOPP implementation. Of course, JNDI itself does not directly support or implement the pattern, but
since it provides a channel for these remote objects, it aids in the distribution.
Prototype
(see page 28): The JNDI architecture provides a few Prototype implementations to support the
duplication of objects. In JNDI, this pattern mostly applies to lookup resources, the objects used to keep track of
resource names or directory attributes:
javax.naming: Reference, Name, CompoundName, CompositeName
javax.naming.directory: BasicAttribute, Attributes, Attribute, BasicAttributes
