m2 j2ee services

8/9/2019 M2 J2EE Services

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J2EE ServicesJ2EE Services

Technology Consulting Technology Consulting

PramatiPramati TechnologiesTechnologies


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J2EE ServicesJ2EE Services

Services provided areServices provided areJNDI (Java Naming and Directory Service)JTA (Java Transaction API)

JAAS (Java Authorization and Authentication Service)JMS (Java Message Service)JCA (J2EE Connector Architecture)RMI-IIOP (Inter-operability)JDBC (Java Database Connectivity)JavaMailJAXP (Java API for XML Parsing)


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Naming Services & JNDI Naming Services & JNDI


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Naming Services:Overview Naming Services:Overview

Requirement:Requirement:Distributed applications require something to helpDistributed applications require something to helpthe components to find each other the components to find each other

The Java Naming and Directory Interface (JNDI)The Java Naming and Directory Interface (JNDI) provides just this capability. provides just this capability.


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Naming Services Naming Services

Maintains a set of Maintains a set of b indings.b indings.Bindings relate names to objects.Bindings relate names to objects.

Naming Convention Naming Convention - - All objects in aAll objects in anaming system are named in the same waynaming system are named in the same wayClients use the naming service to locateClients use the naming service to locateobjects by name.objects by name.


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Existing naming servicesExisting naming services

DNS (Domain Name SystemDNS (Domain Name SystemLDAP (Lightweight Directory AccessLDAP (Lightweight Directory Access

Protocol):Protocol):NIS (Network Information System) NIS (Network Information System)COS (Common Object Services) NamingCOS (Common Object Services) Naming


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A look at JNDI namingA look at JNDI naming

JNDI is anJNDI is an interfaceinterface rather than anrather than animplementation.implementation. Advantage

Allows JNDI to integrate seamlessly into an existingcomputing environment where an established naming serviceholds sway.

DisadvantageNeed access to an existing naming service ( such as LDAPservice) and hence the need to understand something abouthow it works in order to play with JNDI.


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Context and InitialContextContext and InitialContext

The Context interface:The Context interface: Represents a set of bindings Provides the methods for binding names to objects and unbinding

names from objects, for renaming objects, and for listing the bindings.

provides methods for creating and destroying subcontexts

InitialContext class:InitialContext class: This class is instantiated with properties that define the type of

naming service in use and, for naming services that providesecurity, the ID and password to use when connecting.


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Context's methods:Context's methods:

void bind(String stringName, Object object)void rebind(String stringName, Object object)Object lookup(String stringName)void unbind(String stringName)void rename(String stringOldName, String stringNewName)NamingEnumeration listBindings(String stringName)NamingEnumeration list(String stringName)

The Context interface also provides methods for renamingand listing bindings.


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Container Naming ServicesContainer Naming Services

Provide application clients, enterprise beans, andWeb components with access to a JNDI namingenvironment

naming environment allows a component to becustomized without the need to access or changethe components source code.Container implements the componentsenvironment, provides it to the component as aJNDI naming contex t.


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Container Naming ServicesContainer Naming Services

Tech detailsTech details A component creates a javax.naming.InitialContext

object

looks up the environment naming context inInitialContext under the name java:comp/en v. object should be named within a subcontext of the

naming environment according to the type of the object. For example

EJBs are named within the subcontext java:comp/env/ejbJDBC DataSource references in the subcontext

java:comp/env/jdb c.


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Naming Services Naming Services

Example code to show naming servicesExample code to show naming services


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Transactions & JTATransactions & JTA


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TransactionsTransactions General OverviewGeneral Overview

Ensure data integrityFree an application programmer from dealing with the

complex issues of failure recovery and multi-user programming.

Properties of Transactions ACIDAtomicityConsistencyIsolationDurability


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J2EE Platform TransactionsJ2EE Platform Transactions

Programmatic TransactionsProgrammatic TransactionsDeclarative TransactionsDeclarative Transactions Burden of implementation is on Container Provider Responsibilities of Server Provider

Interactions between Transaction Manager and JDBC DatabaseTransaction context propagationTwo-phase commit

Support for flat transactions


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JTA & JTSJTA & JTS

What is JTA?Specifies standard Java interfaces between a

transaction manager and the partiesinvolved in a distributed transaction system Transactional application J2EE server

Transaction Manager


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JTA & JTSJTA & JTS

What is JTS?What is JTS?Specifies the implementation of a transaction manager thatsupports JTA and implements the Java mapping of the

OMG Object Transaction Service (OTS) specification atthe level below the API.JTS implementation is transparent to J2EE components.Components should never interact directly with JTS. Theyshould use the JTA Us erTran s action interface for transaction demarcation.


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JTA & JTSJTA & JTS


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JTA TransactionsJTA Transactions

JTA transactionJTA transaction Managed andManaged andcoordinated by the J2EE platformcoordinated by the J2EE platformSpan multiple components and enterpriseSpan multiple components and enterpriseinformation systemsinformation systemsPropagated automatically betweenPropagated automatically betweencomponents and to EIS accessed bycomponents and to EIS accessed by

componentscomponents


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JTA TransactionsJTA Transactions

Ways to start a JTA transactionWays to start a JTA transactionBean managed transaction demarcationBean managed transaction demarcation

javax.transaction.UserTransaction javax.transaction.UserTransactionContainer managed transaction demarcationContainer managed transaction demarcation

Started automatically by EJB container based on theStarted automatically by EJB container based on thetransaction attributestransaction attributes

Main BenefitMain BenefitAbility to combine multiple components and enterpriseAbility to combine multiple components and enterpriseinformation system accesses into one single transactioninformation system accesses into one single transactionwith little programming effort.with little programming effort.


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Transaction Manager ImplementationTransaction Manager Implementation


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J2EE Transactional ModelJ2EE Transactional Model

Transactions in Enterprise Beans

Transaction Attributes

RequiredRequires New

Not SupportedSupports

Mandatory Never


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J2EE Transactional ModelJ2EE Transactional Model

Transaction Attribute GuidelinesDefault choice RequiredRequires New useful when bean method requiresunconditional commit

NotSupported resource manager responsible for thetransaction is not supported by the J2EE product.Supports Not recommended because of unpredictable

behaviour


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Container Transaction ServicesContainer Transaction Services

TransactionsTransactions ACID propertyACID property Atomicity Consistency Isolation

Durability

J2EE transactions are flatJ2EE transactions are flatJ2EE platform implicitly handles many transactionJ2EE platform implicitly handles many transactiondetails,details,

Transaction propagation coordinating among multiple transaction managers.


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Container Transaction ServicesContainer Transaction Services

EJB TransactionsEJB TransactionsBean Managed Transaction DemarcationBean Managed Transaction Demarcation EJB manages all aspects of transaction

Container Managed Transaction DemarcationContainer Managed Transaction Demarcation Container container handles transaction management based on the Application Assemblers deployment instructions

Entity Beans can use only Container ManagedEntity Beans can use only Container Managed

Transaction DemarcationTransaction Demarcation


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Transactions in EISTransactions in EIS

Components should always access an EIS under the scope of a transaction

JTA TransactionsThe J2EE server is responsible for coordinating and propagatingtransactions between the server and the enterprise information system.

Components can access and perform updates on multiple EISatomically

Resource Manager Local TransactionsTransaction specific to a particular EIS connectionAccess to a transactional EIS will be under a local transaction if noJTA transaction has been initiated.


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Transactions in EISTransactions in EISCompensating Transactions

Transaction or a group of operations that is used to undo the effect of a previously committed transactions.

updateERPSystem();try {UserTransaction.begin();updateJDBCDatabaseOne();updateJDBCDatabaseTwo();UserTransaction.commit();

}catch (RollbackException ex) {

undoUpdateERPSystem();}}


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Isolation LevelsIsolation Levels

Defines how concurrent transactions to anenterprise information system are isolated fromone another.The API for managing an isolation level isresource-manager specific.Hence the EJB architecture does not define an APIfor managing isolation level


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Security Services & JAASSecurity Services & JAAS


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Security ServicesSecurity Services

Ensure that resources are accessed only byEnsure that resources are accessed only byusers authorized to use them.users authorized to use them.Access control involves two steps:Access control involves two steps: Authentication Authorization


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Security MethodologiesSecurity Methodologies D eclarative security Programmatic security


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AuthenticationAuthentication entity must establish its identity through authenticatio n. typically does so by providing authentication data entity that can be authenticated is called a principa l. principal can be a user or another program

Types of AuthenticationTypes of Authentication Basic Digest

Form Based Certificate


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AuthorizationAuthorization system determines whether the principal is authorized to access

resources based on the security policies

S ecurity roleS ecurity role - - logical grouping of users that islogical grouping of users that isdefined by an Application Component Provider or defined by an Application Component Provider or Application Assembler.Application Assembler.Each security role is mapped by a deployer toEach security role is mapped by a deployer to

principals in the deployment environment. principals in the deployment environment.

Control access to an enterprise beans methods byControl access to an enterprise beans methods byspecifying thespecifying the method method- -permission permission


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JAAS GoalsJAAS Goals

1.1. Pluggable authenticationPluggable authentication Authentication Mechanism couldAuthentication Mechanism could be plugged into Authentication Frame Work. be plugged into Authentication Frame Work.

2.2. PolicyPolicy--based authentication based authentication can modify your policy file for can modify your policy file for granting permission.granting permission.

3.3. Stackable authenticationStackable authentication Multiple authentication mechanismMultiple authentication mechanismmay be pluggedmay be plugged

Adds value to java platform but is physically separate fromAdds value to java platform but is physically separate fromJava 2 Security Policy.Java 2 Security Policy.


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How to authenticate?How to authenticate?

Subject and Principals are created after AuthenticationSubject and Principals are created after AuthenticationTo request for Authentication, user has to createTo request for Authentication, user has to create

javax.security.auth.LoginContext Object. javax.security.auth.LoginContext Object.javax.security.auth.LoginContext {public void login();public Subject getSubject();Public void Logout();}

loginContext creates a Subject for Authentication.loginContext creates a Subject for Authentication.User cant create a subject .User cant create a subject .


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Messaging Services & JMSMessaging Services & JMS


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MessagingMessaging

Messages are asynchronous requests, reports or Messages are asynchronous requests, reports or events that are consumed by enterpriseevents that are consumed by enterpriseapplicationsapplications

contain vital information needed to coordinatecontain vital information needed to coordinatethese systems.these systems.contain precisely formatted data that describecontain precisely formatted data that describespecific business actions.specific business actions.


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JMSJMS

Standard API for messagingStandard API for messagingCommon way for Java programs to create, send,Common way for Java programs to create, send,receive and read an enterprise messaging systemsreceive and read an enterprise messaging systems

messages.messages.Asynchronous processingAsynchronous processingTwo messaging modelsTwo messaging models Point to Point Model Publish Subscribe Model


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Architecture

A JMS Application is composed of:

JMS Clients programs that send and receivemessages.Messages each app defines a set of messagesthat are used to communicate between them.JMS provider the server which brokersmessages

Administered Objects pre-configured JMSobjects created by administrator for the use of clients


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JMSJMS

Publish/Subscribe Messaging ModelPublish/Subscribe Messaging Model

Application Topic

Application

Application

JMS

Publish Subscribe


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JMS Administered ObjectsJMS Administered Objects

Types of Administered ObjectsConnectionFactory

used to create connectionsDestination

represent the specific destinations the messages are sentto and recvd from. These are placed in a JNDInamespace by the administrator.


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JMS Concepts(interfaces)JMS Concepts(interfaces)

ConnectionFactoryConnectionFactory used by a client to create aused by a client to create aConnectionConnectionConnectionConnection An active connection to a JMS provider An active connection to a JMS provider DestinationDestination encapsulates the identity of a messageencapsulates the identity of a messagedestinationdestinationSessionSession single threaded context for sending and receivingsingle threaded context for sending and receivingmessagesmessagesMessageProducer MessageProducer object created by a Session that is usedobject created by a Session that is usedfor sending messages to a destinationfor sending messages to a destinationMessageConsumer MessageConsumer object created by a Session that isobject created by a Session that isused for receiving messages sent to a destinationused for receiving messages sent to a destination


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Developing a JMS clientDeveloping a JMS client

A typical JMS client executes the followingA typical JMS client executes the followingUse JNDI to find a ConnectionFactory objectUse JNDI to find a ConnectionFactory objectUse JNDI to find one or more Destination objectsUse JNDI to find one or more Destination objectsUse the ConnectionFactory to create a JMS Connection with messageUse the ConnectionFactory to create a JMS Connection with messagedelivery inhibiteddelivery inhibitedUse the Connection to create one or more JMS SessionsUse the Connection to create one or more JMS SessionsUse a Session and the Destinations to create the MessageProducers andUse a Session and the Destinations to create the MessageProducers andMessageConsumers neededMessageConsumers neededTell the Connection to start delivery of messagesTell the Connection to start delivery of messages


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Developing JMS clientDeveloping JMS client

Code exampleCode example


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Java Connector ArchitectureJava Connector Architecture


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Java Connector ArchitectureJava Connector Architecture

Defines a standard architecture for connecting theDefines a standard architecture for connecting theJ2EE platform to heterogeneous EISs. (e.g. ERP,J2EE platform to heterogeneous EISs. (e.g. ERP,mainmain--frame transaction processing (TP), andframe transaction processing (TP), and

database systems.)database systems.)Defines a Common Client Interface (CCI) for EISDefines a Common Client Interface (CCI) for EISaccess.access.Enables an EIS vendor to provide a standardEnables an EIS vendor to provide a standard

resource adapter which plugs into an applicationresource adapter which plugs into an applicationserver server


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ConnectorsConnectors

Database

IBM

ApplicationServer


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ConnectorsConnectors - - salient featuressalient features

Connectors sit beneath the J2EE platformConnectors sit beneath the J2EE platformDefine a portable service API to plug into existingDefine a portable service API to plug into existingenterprise vendor offeringsenterprise vendor offeringsProvide standard client APIProvide standard client API


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Interoperability & RMIInteroperability & RMI- -IIOPIIOP


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InteroperabilityInteroperability

RequirementsRequirementsJ2EE applications to connect to legacy systems usingJ2EE applications to connect to legacy systems usingCORBA or lowCORBA or low- -level Socket interfaces.level Socket interfaces.

J2EE applications to connect to other J2EE applicationsJ2EE applications to connect to other J2EE applicationsacross multiple J2EE products, whether from differentacross multiple J2EE products, whether from differentProduct Providers or from the same Provider, and multipleProduct Providers or from the same Provider, and multiple

J2EE platformsJ2EE platforms ..


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InteroperabilityInteroperability


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Other ServicesOther ServicesJDBC, JavaMail, JAXPJDBC, JavaMail, JAXP


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JDBCJDBC

Provides databaseProvides database- -independent connectivityindependent connectivity between the J2EE platform and a wide range of between the J2EE platform and a wide range of tabular data sources.tabular data sources.Perform connection and authentication to aPerform connection and authentication to adatabase server database server Manage transactionsManage transactionsMove SQL statements to a database engine for Move SQL statements to a database engine for

preprocessing and execution preprocessing and executionExecute stored proceduresExecute stored proceduresInspect and modify the results from SelectInspect and modify the results from Selectstatementsstatements


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JavaMailJavaMail

Allows an application component to sendAllows an application component to sendInternet mail.Internet mail.Has two partsHas two parts an application-level interface used by the application

components to send mail a service provider interface used at the J2EE SPI level.


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JAXPJAXP

Provides support for the industry standardProvides support for the industry standardSAX and DOM APIs for parsing XMLSAX and DOM APIs for parsing XMLdocuments, as well as support for XSLTdocuments, as well as support for XSLTtransform engines.transform engines.


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