Java Naming and Directory Interface

Contents Naming and directory services JNDI RMI Conclusion

Naming and directory services

Naming service Means by which names are associated with objects Examples:  Electronic mail system  File system  Domain name system

Some definitions Binding – the association of a name with an object Reference – represents information about how to access an object Context – set of name-to-object bindings  has an associated naming convention  name in one context object can be bound to another context object (subcontext)

Directory service Associates names with objects and also associates such objects with attributes Directory service = naming service + objects containing attributes (directories)

Some more definitions Directory object – object with attributes Directory – connected set of directory objects

JNDI

JNDI API – provides naming and directory functionality to Java applications  Independent of any specific directory service implementation JNDI Server provider interface (SPI) – enables a variety of naming and directory services to be plugged in transparently

JNDI architecture

Context javax.naming.Context – the core interface  looking up  list bindings  binding/unbinding  renaming objects  creating subcontexts  destroying subcontexts

Initial context Hashtable args = new Hashtable(); args.put( Context.INITIAL_CONTEXT_FACTORY, "com.jndiprovider.TheirContextFactory"); args.put( Context.PROVIDER_URL, " ); myCurrentContext = new InitialContext(args);

Directory context javax.naming.directory.DirContext – interface represents a directory context  getAttributes()  modifyAttributes()

Event package javax.naming.event – contains classes and interfaces for supporting event notification in naming and directory services  NamingEvent – an event that is generated by a naming/directory service  NamingListener – an object that listens for NamingEvents

Service provider package javax.naming.spi – provides the means by which naming/directory service providers can be hooked up The corresponding services are accessible from applications that use the JNDI

RMI

Often comprise two separate programs, a server and a client The mechanism by which the server and the client communicate and pass information back and forth

Server & client Typical server  Creates some remote objects  Makes references to these objects accessible  Waits for clients to invoke methods on these objects Typical client  Obtains a remote references to some remote objects on a server  Invokes methods on them

Remote objects An object becomes remote by implementing a remote interface  A remote interface extends the interface java.rmi.Remote  Each method of the interface declares java.rmi.RemoteException in its throws clause java.rmi.registry.Registry – API for binding (or registering) and looking up remote objects in the registry

Conclusion

References d_Directory_Interface d_Directory_Interface dex.html dex.html dex.html dex.html

Questions