Download javaEE_L_0011

Topic : JNDI
Kaster Nurmukan
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JNDI
What is JNDI?
Naming and Directory Services
Naming Concepts
Issues
JNDI Architecture
Programming with JNDI
Role of JNDI in J2EE
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(c)CDAC(Formerly NCST)
• Class.forName("com.microsoft.jdbc.
sqlserver.SQLServerDriver");
• cnn = DriverManager.getConnection
("jdbc:microsoft:sqlserver://siddh
ant:1433",“username",“password");
JNDI
3
(c)CDAC(Formerly NCST)
• Context ctx = new InitialContext();
• DataSource ds =
(DataSource)ctx.lookup(“myname”);
• Connection con = ds.getConnection(“abc”,”***”);
JNDI
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(c)CDAC(Formerly NCST)
Java Naming and Directory Interface (JNDI) provides a
standard interface for Java applications to access naming
and directory services.
JNDI
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•
Naming Service performs:
– Binding: Associating names with objects
– Lookup: Find an object based on a name.
• Examples: DNS and File systems
• Examples:
– DNS
– Filesystems
JNDI
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(c)CDAC(Formerly NCST)
• Directory is a naming service that stores
objects with attributes.
– Usernames and passwords etc stored in attrs.
• Tree like structure
JNDI
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(c)CDAC(Formerly NCST)
• Atomic name is a indivisible component of a
name
– in /etc/fstab, etc and fstab are atomic names.
• Compound name is zero or more atomic
names put together.
– /etc/fstab is a compound name
JNDI
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• Binding is an association of a name with an
object.
– Filename “autoexec.bat” has a binding to
some
file data on the disk.
– “c:\windows” foldername is bound to a folder
on your drive.
• Compound
name
such
as
/usr/people/ed/.cshrc
consists of multiple bindings, one to usr, one
to
people, one to ed, and
JNDI
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• Contains zero or more bindings.
– Each binding has a distinct atomic name.
• /etc contains files named mtab and exports.
• The /etc folder is a context containing
bindings with atomic names mtab and
exports.
• mtab and exports are each bound to a file on
the disk.
JNDI
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(c)CDAC(Formerly NCST)
• /usr – CONTEXT
– /usr/people – SUB-CONTEXT
– /usr/bin – SUB-CONTEXT
– /usr/local – SUB-CONTEXT
• Each atomic name is bound to a sub-context the
subfolder.
• Subcontext are full-fledged contexts
• Can contain more name-object bindings, such as
other files or other folders.
JNDI
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• Naming system: A connected set of
contexts.
• Namespace: all the names contained within
that naming system.
JNDI
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• Starting point for exploring a namespace.
• Starting point for performing all naming and
directory operations.
JNDI
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• Many naming and directory products.
– Netscape Directory Server
– MicrosoftActiveDirectory
• Various naming and directory protocols: Each
directory standard has a different protocol for
accessing the directory.
– Lightweight Directory Access Protocol
(LDAP)
– Network Information System (NIS)
– Novell’s Network Directory System (NDS)
• EveryDS has it’s ownAPI.
JNDI
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• Standard interface to interact with naming and
directory systems.
• For Java programs.
• Provides common interface to disparate
directories: Same API for LDAP and NIS NDS.
• Used in EJB, RMI-IIOP, JDBC for operations like
locating entities i.e. Users, Machines (e.g. printer),
Objects, Services (e.g. datasource) etc.
JNDI
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• The client API
– Allow Java code to perform directory
operations.
• The Service Provider: Driver
• The Service Provider Interface (SPI)
– An interface to which naming and directory
service vendors can plug in.
JNDI
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JNDI
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The JNDI comprises of 5 packages
• javax.naming – Contains classes and interfaces
for accessing naming services
• javax.naming.directory – Extends javax.naming
and provides functionality to access directory
services in addition to naming services
JNDI
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(c)CDAC(Formerly NCST)
• javax.naming.event
–
Classes
and
interfaces for supporting event notification in
naming and directory services
• javax.naming.ldap – Classes and interfaces
for using features that are specific to LDAP v3
that are not already covered by the more
generic javax.naming.directory
• javax.naming.spi – Vendors develop their
naming/directory services conforming to SPI.
Applications can then access these services
through the JNDI API
JNDI
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(c)CDAC(Formerly NCST)
• Used to acquire an initial context
• Implementation of the JNDI driver: Knows the
specific semantics of a particular directory
structure.
• bootstrapping.
• Necessary information for JNDI to acquire that
initial context.
– The IP address of the J2EE server
– The port number that the J2EE server
accepts
– Any username/password necessary to use
JNDI the J2EE server.
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(c)CDAC(Formerly NCST)
javax.naming.Context ctx =
new javax.naming.InitialContext
(System.getProperties());
java
-Djava.naming.factory.initial=
com.sun.jndi.fscontext.RefFSContextFactory
-Djava.naming.provider.url=
file:c:\examples.InitCtx
class of the JNDI driver
• provider URL: URL that the service provider
accepts for bootstrapping.
JNDI
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Methods invoked on a Context
• list() - list of contents available at the context.
– names of objects bound to the JNDI tree
– subcontexts.
• lookup() - look up objects bound to the JNDI
tree
– Return type is driver specific
• RMI-IIOP java.rmi.Remote
• file system java.io.File
JNDI
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• rename() - give a new name to a context
– c:\temp to c:\tmp
• createSubcontext() - create a subcontext at the
context
– c:\foo\bar at the folder c:\foo.
• destroySubcontext() - destroy a subcontext of
the
context
– Destroy c:\foo\bar from the folder c:\foo.
• bind() – associates a name to a content and
stores
it at the Context
– JNDI drivers accept different parameters to
JNDIbind()
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(c)CDAC(Formerly NCST)
import javax.naming.*;
public class Startup {
public static void main(String args[]) throws
Exception {
AccountImpl acct_impl = new AccountImpl();
Context
ctx
=
new
InitialContext
(System.getProperties());
ctx.rebind(“myname", acct_impl);
}
}
JNDI
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(c)CDAC(Formerly NCST)
import javax.naming.*;
import java.rmi.*;
public class Client {
public static void main (String[] args) throws
Exception { Context ctx = new InitialContext
(System.getProperties());
Object remoteObject = ctx.lookup(“myname");
Account account = (Account)
javax.rmi.PortableRemoteObject.narrow (
remoteObject, Account.class);
int b = account.method1(5));}}
JNDI
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• J2EE servers have a JNDI implementation.
• Used to Look up beans.
• Connect to resource factories
– JDBC DataSource
– Java Message Service (JMS) drivers
• Acquiring a reference to the Java
Transaction API’s (JTA) UserTransaction
interface.
JNDI
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• Mastering Enterprise JavaBeans by Ed
Roman et. al. (Wiley)
• JNDI Tutorial on java.sun.com
• Java Server Programming J2EE Edition –
Volume 1 – Wrox.
• Java Enterprise in a nutshell – David
Flanagan et. Al. – O’reilly
JNDI
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