Java Naming and Directory Interface JNDI. v001025JNDI2 Topics Naming and Directory Services JNDI Overview Features and Code Samples JNDI Providers References.

Java Naming and Directory Interface

JNDI

v001025 JNDI 2

Topics

Naming and Directory Services

JNDI Overview

Features and Code Samples

JNDI Providers

References

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Naming Service

Associate names with objects (bind)

Retrieve objects by their name (lookup)

Examples: RMI Registry CORBA Naming Service (COSNaming) Domain Name Service (DNS) File system

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Contexts

Contains a set of bindings and lookup operations

Has its own naming convention

Examples File system directory: “/” DNS domain: “edu” LDAP: “c=us”

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Names

Logical identifier assigned to an object

Naming convention defined by Naming System

Examples /dir/dir2/file for UNIX drive:\dir\string for DOS cn=dan, o=ISP for LDAP www.cise.ufl.edu for DNS

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Names (Cont)

Atomic Name name used in a binding Ex. filename in a directory

Compound Name sequence of atomic names /usr/bin/ls

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Names (Cont)

Composite Nameapplies multiple naming systemshttp://www.apl.jhu.edu/~weimer/

URL scheme id: httpDNS: www.apl.jhu.eduUNIX and webserver: /usr/weimer/public_html

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Directory Service

Can obtain an object with attributes and search for objects based on attributes

Current Directory Systems X.500 - ISO standard. Complex. LDAP - Simplified X.500 over TCP/IP NDS - Novell Directory Services. NIS - Directory service for Solaris

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Attributes

Common LDAP Attributesc = Country

o = Organization

ou = Organizational Unit

cn = Common Name (typically first or full name)

sn = User’s surname

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Naming and Directory Targets

Resourcesprintersmachines

Users

Java Objects !

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Naming Vs. Directory

Naming Services simply assign logical names to addresses or objects localhost => 127.0.0.1 white pages

Directory Services add attributes and attribute-based searching find all hosts that are Sparc Solaris and have available disk

space yellow pages

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JNDI Goals

Provide a consistent API to access different naming and directory services. Clients learn one API.

Different naming and directory systems can be combined into one logical system

New naming service implementations can be added with no client modifications

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JNDI Architecture Overview

JNDI API

JNDI Service Provider Interface

Java Client Application

JNDI Naming Manager

DNS LDAP CORBARMI Anything

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JNDI Architecture

Application Programming Interface (API)API for client programmerUnifying interface

Service Provider Interface (SPI)For vendors enabling JNDI access to their

naming/directory service

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JNDI API

Included in Java 2 SDK v 1.3

Have to download for JDK 1.1 and SDK 1.2

Packages javax.naming javax.naming.directory javax.naming.event javax.naming.ldap javax.naming.spi

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Service Providers

Implementation for underlying products

Included in Java 2 SDK 1.3LDAPCOSNamingJNDI over RMI Registry

Have to download for previous versionshttp://java.sun.com/products/jndi/

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Common JNDI Tasks

Obtain reference to initial contextContext OperationsList children of a contextBind names to objectsLookup objects via name Create/destroy contextsNote: NamingException can be thrown

from most Context operations

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JNDI Contexts

javax.naming.Context

bind(String name, Object obj)createSubcontext(String name) : Contextlist(String name) : NamingEnumerationlistBindings(String name) : NamingEnumerationlookup(String name) : Object

<<abstract>>

javax.naming.InitialContext

InitialContext()InitialContext(java.util.Hashtable env)

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Obtain Initial Context

import javax.naming.*;

java.util.Properties props = new java.util.Properties();

props.put(Context.INITIAL_CONTEXT_FACTORY,

“com.sun.jndi.fscontext.RefFSContextFactory”);

props.put(Context.PROVIDER_URL, “file:///”);

Context initContext = new InitialContext( props );

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Initial Context

Starting point in the namespace

All operations performed are relative to the initial context

Specify service provider with property

props.put(Context.INITIAL_CONTEXT_FACTORY”,

“com.sun.jndi.fscontext.RefFSContextFactory” );

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Initial Context (Cont)

Specify provider-specific propertiesLDAPprops.put(Context.PROVIDER_URL, “ldap://host:port”);props.put(Context.SECURITY_PRINCIPAL, “user” );props.put(Context.SECURITY_CREDENTIALS, “password”);

File Systemprops.put(Context.PROVIDER_URL, “file://tmp/”);

CreateInitialContext initContext = new InitialContext( props );

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List children

NamingEnumeration children = initContext.list(“”);

while( children.hasMore() )

{

NameClassPair nc = (NameClassPair) children.next();

System.out.println(nc.getName());

System.out.println(nc.getClassName());

}

list() returns a NamingEnumeration of NameClassPair objects

listBindings() returns a NamingEnumeration of Binding objects

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Binding Names to an Object

Bind name to object within a context

File f = new File(“/tmp/dan”);tmpDirContext.bind(“dan”, f );

NameAlreadyBoundException occurs if “dan” is already bound in the tmp contextCan use unbind() or rebind()

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Object Lookup

Lookup object in a contextString name; Object o =

initContext.lookup(name);name can be compound

“/usr/tmp/dir/myfile”Filesystem provider returns

File for files

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Attributes

DirContext contains an object with attributes for each contained binding

Common LDAP Attributesc = Country

o = Organization

ou = Organizational Unit

cn = Common Name (typically first or full name)

sn = User’s surname

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Basic Search

Specify a set of attributes that an entry must have.

Specify required attribute values

Specify attributes to returnsearch(String name, Attributes match, String[]

retAttrIds )

Returns NamingEnumeration of SearchResults

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Storing objects

Object Types to storeJava Serializable ObjectReferenceable Java ObjectRemote Objects like RMI and CORBA

objects

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Federation

Composite names span multiple namespacesou=People/tmp/myFileFile f = (File)

ctx.lookup(“ou=People/tmp/myFile”);

lookup on this name will traverse through LDAP and the Filesystem provider to retrieve the file

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JNDI Providers

LDAP com.novell.naming.service.nds.NdsInitialContextFactory

NIS com.sun.jndi.nis.NISCtxFactory

RMI com.sun.jndi.rmi.registry.RegistryContextFactory

COSNaming ( CORBA Naming System )

Files com.sun.jndi.fscontext.[Ref]FSContextFactory

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Setup Requirement

For 1.3, essentially nothing. JNDI should be included in the distribution along with the 3 providers

For Java 2 SDK version 1.2 jndi.jar in $JAVA_HOME/jre/lib/ext

For jdk 1.1Add jndi.jar to the CLASSPATH

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Summary

Provide a consistent API to access different naming and directory services. Clients learn one API.

Different naming and directory systems can be combined into one logical system

New naming service implementations can be added with no client modifications

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Resources

JNDI API Tutorial and Reference, Rosanna Lee and Scott Seligman. Addison Wesley, 2000

Main JNDI Page http://java.sun.com/products/jndi/

Java Lecture Source http://www.apl.jhu.edu/~jcstaff/ejava/ejava_whatsnew_f00.htm

Java Online Tutorial http://java.sun.com/docs/books/tutorial/