As we move into the object-oriented world of Java and WebSphere, we find ourselves faced with a world in which our systems expand from one central computer to a universe of computers scattered around the world. Your applications may reside on a single computer, but more than likely they will expand to consist of system components spread across many networks connected by the Internet.
A fundamental problem in distributed systems is the ability to find objects and obtain information about them. This is the job of the Java Naming and Directory Interface (JNDI). The JNDI is not a directory, but rather a standardized interface to standards-based directory servers. IBM and the iSeries currently support two implementations of the JNDI. WebSphere 3.x and 4.0 implement a directory within the WebSphere product. The most typical implementations of the JNDI are, however, built over an industry standard Lightweight Directory Access Protocol (LDAP) server. The iSeries has included an LDAP server with OS/400 since V4R3. At V4R5, it was enhanced to support the LDAP Version 3 protocol as defined by the Internet Engineering Task Force and bundles the JNDI with it.
The JNDI is a standard Java programming interface that allows you to interrogate or update vendor-provided directory servers. You learn one interface and code to the JNDI standards regardless of where the data might be stored.
You can locate directory information about any type of object stored in a system directory, retrieve attributes describing the object, update the object or perform other operations on the object. The JNDI can find programs, people, machines or any resource defined to a directory server. The interesting aspect of the JNDI is that systems can use the JNDI to discover information about their partner systems.
To learn about the JNDI visit http://java.sun.com/products/jndi/tutorial/trailmap.html. And for information about the iSeries LDAP server and its JNDI implementation, visit http://www-1.ibm.com/servers/eserver/iseries/ldap/ .
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About the author: Bob Cancilla is managing director of IGNITe/400, an electronic iSeries 400 Internet users group. He is also author of the book Getting Down to e-business with AS/400
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This was first published in July 2001