Naming

1
Naming Directory Service

• ? ? ?
• Database lab, Dept. of CS, KAIST
• mylim_at_dbserver.kaist.ac.kr

2
Contents

• E-commerce system
• Directory service
• Lightweight Directory Access Protocol(LDAP)
• Java Naming and Directory Interface(JNDI)
• Java 2 Platform, Enterprise Edition

3
Architecture
E-commerce system

• Overview

4
Architecture
E-commerce system

• Components

5
Architecture
E-commerce system

• Application server

Source Tmax Soft
6
Concept
Directory service

• Directory
• Specialized database that stores information
  about objects
• List information about printers
• Allow user or application to find resources that
  have the characteristics needed for a task
• Find a server that can access customer billing
  information
• White and yellow pages

7
Comparison with database
Directory service

• Optimized for read access
• High volumes of Read and Search request
• Rare update request
• No transaction
• Anomalies are considered acceptable
• The way information can be accessed
• LDAP URL

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Roles
Directory service

• Vital part of the infrastructure
• Provide a single logical view of the users,
  resources, and other objects that make up a
  distributed system
• Allow users and applications to access network
  resources transparently

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LDAP Introduction

• Background
• Many network-based application rely on their own
  directories(or database)
• information describing various users,
  application, files and other resources accessible
  from the network
• Application-specific directory
• Much information is common
• Consistency problem
• The number of specialized directories grow and
  are difficult to maintain

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Introduction
LDAP

• Need to maintain and access all of this
  information in a consistent and controlled manner
• Need common, application-independent directory
• Directory Access Protocol
• Can integrate a distributed environment into a
  consistent and seamless system

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X.500
LDAP

• Directory service
• Data Communications Network Directory,
  Recommendations X.500-X.521
• Oraganize directory entries in a hierarchal name
  space
• Define powerful search capabilities
• Directory Access Protocol(DAP)
• Communication between directory client and server
• Use OSI protocol stack
• Resource intensive protocol

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Definition
LDAP

• Lightweight Directory Access Protocol
• Define a standard method for accessing and
  updating information in a directory
• Communication protocol
• Do not define a programming interface
• Open industry standard
• Lightweight Access to X.500
• Use TCP/IP protocol stack
• Simplify some X.500 operations

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LDAP server
LDAP

• Gateway to an X.500 server
• Stand-Alone

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Interaction
LDAP

• General interaction
• Binding 1, 2
• Unbinding 5

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LDAP model
LDAP

• Information model
• Describe the structure of information
• Naming model
• Describe how information is organized and
  identified
• Functional model
• Describe what operations can be performed on the
  information
• Security model
• Describe how the information can be protected

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Information model
LDAP

• Relationship
• Entries
• The directory stores and organizes data
  structures
• An object such as a person, a server and so on

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Information model
LDAP

• Object class
• General description of an object called template
• Described by schema
• What object classes are allowed where in
  directory
• What attributes they must contain
• What attributes are optional
• The syntax of each attribute
• Inheritance and subclassing of objects

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Naming model
LDAP

• Directory Information Tree(DIT)
• Organize entries based on their DN
• Distinguished Name(DN)
• Identify a entry uniquely
• A sequence of relative DN(RDN) separated by
  commas
• From leaf to root node
• ltattribute namegtltvaluegt,ltattribute
  namegtltvaluegt, ...
• Not a tree
• Can use aliases

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Naming model
LDAP

• Example DIT
• cnJohn,ouLDAP Team,oIBM,cUS
• cnJohn Smith,oIBM,cDE

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Naming model
LDAP

• Suffixes and Referrals
• Support distributed directory
• Suffixes
• Individual LDAP server might not store the entire
  DIT
• Referrals
• Form a distributed directory that contains the
  entire DIT
• An entry of objectClass referral
• Have an attribute, ref, whose value is the LDAP
  URL of the referred entry on another LDAP server
• Managed by client or LDAP server
• Off-loading the work of contacting other servers
  to the client

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Naming model
LDAP

• Example

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Functional model
LDAP

• Query operation
• Search parameters

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Functional model
LDAP

• Update
• Entries attributes
• Add, delete
• Attributes value DN
• Modify
• Authentication
• Bind Unbind

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Security model
LDAP

• Issues
• Authentication
• Integrity
• Confidentiality
• Authorization
• Simple Authentication and Security Layer
• Authentication systems
• e.g. Kerberos
• Secure Socket Layer(SSL/TLS)

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URL
LDAP

• URL format for LDAP resources
• ldaps//lthostgtltportgt/ltdngt?ltattributesgt
  ?ltscopegt?ltfiltergt?ltextensionsgt
• Can simply name an LDAP server
• Can specify a complex directory search
• ldap//saturn.itso.austin.ibm.com/oTransarc,cUS?
  cn,mail,phoneNumber?sub?cnbrown

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Deployment example
LDAP

• Replicated LDAP cluster

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Deployment example
LDAP

• Organizations Network

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Commercial products
LDAP

• OpenLDAP
• Free and Open source
• Netscape Directory Server
• IBM's Secure Way Directory
• Microsoft Active Directory Service
• Part of Windows 2000

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Summary
LDAP

• Directory service(or server)
• Most important component in distributed system
• Directory Access Protocol
• Standard communication protocol between directory
  server and client
• Lightweight Directory Access Protocol
• Based on TCP/IP
• Integrate a distributed environment into a
  transparent, consistent and seamless system based
  on Internet

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References
LDAP

• TCP/IP Tutorial and Technical Overview
• Martin W.Murhammer, International Technical
  Support Organization
• Understanding LDAP
• Heinz Johner, International Technical Support
  Organization
• OpenLDAP
• http//www.openldap.org
• RFC 2251 2256

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Java Naming and Directory Interface(JNDI)

• Programming interface to access naming and
  directory services
• Provide Naming and Directory functionality
• associate attributes with objects and searching
  for objects using their attributes
• store and retrieve any type of named Java object

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Concept
JNDI

• Naming concepts
• Naming service
• Look up an object given its name
• Binding
• Association of a name with an object

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Concept

• Directory concepts
• Entry Attributes
• Search filters

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Architecture
JNDI

• Internal overview

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Architecture
JNDI

• Service Provider concepts
• The means by which naming and directory services
  are integrated into the JNDI framework
• An implementation of a context or initial context
  that can be plugged in dynamically to the JNDI
  architecture to be used by the JNDI client
• Support multiple namespaces

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Architecture
JNDI

• Supported Service Provider
• Lightweight Directory Access Protocol(LDAP)
• CORBA services(COS) naming service
• Java Remote Method Invocation(RMI) Registry
• Network Information System(NIS)
• File System
• Domain Name System (DNS)
• Novell NDS

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Packages
JNDI

• Programming API packages
• javax.naming
• Accessing naming services
• javax.naming.directory
• Provide functionality for accessing directory
  services
• javax.naming.event
• Supporting event notification in naming and
  directory service
• javax.naming.ldap
• LDAP v3-specific features that are not covered by
  the more generic javax.naming.directory package
• javax.naming.spi
• Service Provider Interface

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Example code
JNDI

• Naming Example

import javax.naming. class Lookup public
static void main(String args)
Hashtable env new Hashtable(11)
env.put(Context.INITIAL_CONTEXT_FACTORY,
"com.sun.jndi.fscontext.RefFSContextFactory")
String name /tmp/testfile
try Context ctx new
InitialContext(env) Object obj
ctx.lookup(name) ctx.close()
catch (NamingException e)
System.err.println("Problem looking up " name
" " e)
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Example code
JNDI

• Directory Example

class Getattr public static void
main(String args) Hashtable env new
Hashtable(11) env.put(Context.INITIAL_CON
TEXT_FACTORY, "com.sun.jndi.ldap.LdapC
txFactory") env.put(Context.PROVIDER_URL,
"ldap//localhost389/oJNDITutorial")
try DirContext ctx new
InitialDirContext(env) Attributes
attrs ctx.getAttributes("cnTed Geisel,
ouPeople") System.out.println("sn
" attrs.get("sn").get())
ctx.close() catch (NamingException e)
System.err.println("Problem getting
attribute " e)
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Example code
JNDI

• Binding Unbinding

Context ctx . // Create object to be
bound Fruit fruit new Fruit(orange) //
Perform bind ctx.bind(favorite,
fruit) . // Remove binding ctx.unbind(favori
te)
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Programming Patterns
JNDI

• How to access environment entries
• Program code
• Deployment Descripter(DD)

Context initCtx new InitialContext() Context
myEnv (Context)initCtx.lookup(javacomp/env)
Integer max (Integer)myEnv.lookup(maxExemption
s)
ltenv-entrygt ltdescriptiongt The maximum number
of tax exemptions allowed to be set
lt/descriptiongt ltenv-entry-namegtmaxExemptionslt/
env-entry-namegt ltenv-entry-typegtjava.lang.Inte
gerlt/env-entry-typegt ltenv-entry-valuegt15lt/env-
entry-valuegt lt/env-entrygt
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Programming Patterns
JNDI

• How to access database
• Program code
• Property files

Context initCtx new InitialContext() DataSource
ds (DataSource)initCtx.lookup(javacomp/env/jd
bc/AccountDB) Connection con
ds.getConnection()
jdbc.driversoracle.jdbc.driver.OracleDriver jdbc
.datasourcesjdbc/Oraclejdbcoraclethin_at_rtc1521
acct
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Programming Patterns
JNDI

• How to use EJB references
• Program code
• Deployment Descripter(DD)

Context initCtx new InitialContext() Object
result initCtx.lookup(javacomp/env/ejb/EmplRec
ord) EmployeeRecordHome emplRecordHome
(EmployeeRecordHome)javax.rmi.
PortableRemoteObject.narrow(result,EmployeeRecor
dhome.class)
ltejb-refgt ltdescriptiongt This is a reference
to the entity bean lt/descriptiongt
ltejb-ref-namegtejb/EmplRecordlt/ejb-ref-namegt
ltejb-ref-typegtEntitylt/ejb-ref-typegt
lthomegtcom.wombat.empl.EmployeeRecordHomelt/homegt
ltremotegtcome.wombat.empl.EmployeeRecordlt/remotegt
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Clustering methods
JNDI

• Based on JNDI implementation in WAS
• Independent JNDI tree for each application server
• Scalability
• No failover or developers responsibility
• HP Bluestone Total-e-Server, SilverStream App.
  Server
• Centralized JNDI tree cluster
• Utilize CORBAs CosNaming service
• Long cluster convergence
• Sybase Enterprise Application Server
• Shared global and local JNDI tree
• Scalability and high availability
• BEA WebLogic Application Server

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Summary
JNDI

• Unified interface to multiple naming and
  directory services in the enterprise
• Conert with other J2EE technologies to organize
  and locate components in a distributed computing
  environment
• Support real portability and seamless
  connectivity to Java applications
• Flexible architecture

46
References
JNDI

• JNDI tutorial
• http//java.sun.com/products/jndi/tutorial
• Java 2 EE Platform and Component Specification
• Shannon, Addison Wesley 2000
• Java 2 Enterprise Edition homepage
• http//java.sun.com/j2ee/
• JNDI overview
• http//www.javaworld.com/javaworld/jw-01-2000/jw-0
  1-howto.html
• J2EE clustering, Part 1
• http//www.javaworld.com/javaworld/jw-02-2001/

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Java 2 Enterprise Edtion

• J2EE components

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Java 2 Enterprise Edition

• Container
• Allows many component behaviors to be specified
  at deployment time, rather than in program code
• Hide complexity
• Transaction support
• Resource pooling
• Life cycle management
• Enhance portability
• Connector
• Define a portable service API to plug into
  existing enterprise vendor offerings
• Promote flexibility by enabling a variety of
  implementations of specific services

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Application
J2EE

• Contents

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Application
J2EE

• Development phases
• EJB Creation
• Web component Creation
• J2EE App. Client Creation
• J2EE App. Assembly
• J2EE App. Deployment
• Contribution of JNDI DD

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Application
J2EE

• Programming environment

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Application
J2EE

• Application model

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Application
J2EE

• Scenario