The Java EE 5 Tutorial

(1)

The Java EE 5 Tutorial

For Sun Java System Application Server 9.1

Sun Microsystems, Inc. 4150 Network Circle Santa Clara, CA 95054 U.S.A.

(2)

Sun Microsystems, Inc. has intellectual property rights relating to technology embodied in the product that is described in this document. In particular, and without limitation, these intellectual property rights may include one or more U.S. patents or pending patent applications in the U.S. and in other countries.

U.S. Government Rights – Commercial software. Government users are subject to the Sun Microsystems, Inc. standard license agreement and applicable provisions of the FAR and its supplements.

This distribution may include materials developed by third parties.

Parts of the product may be derived from Berkeley BSD systems, licensed from the University of California. UNIX is a registered trademark in the U.S. and other countries, exclusively licensed through X/Open Company, Ltd.

Sun, Sun Microsystems, the Sun logo, the Solaris logo, the Java Coffee Cup logo, docs.sun.com, Java, and Solaris are trademarks or registered trademarks of Sun Microsystems, Inc. in the U.S. and other countries. All SPARC trademarks are used under license and are trademarks or registered trademarks of SPARC International, Inc. in the U.S. and other countries. Products bearing SPARC trademarks are based upon an architecture developed by Sun Microsystems, Inc.

The OPEN LOOK and SunTM_{Graphical User Interface was developed by Sun Microsystems, Inc. for its users and licensees. Sun acknowledges the pioneering efforts} of Xerox in researching and developing the concept of visual or graphical user interfaces for the computer industry. Sun holds a non-exclusive license from Xerox to the Xerox Graphical User Interface, which license also covers Sun's licensees who implement OPEN LOOK GUIs and otherwise comply with Sun's written license agreements.

Products covered by and information contained in this publication are controlled by U.S. Export Control laws and may be subject to the export or import laws in other countries. Nuclear, missile, chemical or biological weapons or nuclear maritime end uses or end users, whether direct or indirect, are strictly prohibited. Export or reexport to countries subject to U.S. embargo or to entities identified on U.S. export exclusion lists, including, but not limited to, the denied persons and specially designated nationals lists is strictly prohibited.

DOCUMENTATION IS PROVIDED “AS IS” AND ALL EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE DISCLAIMED, EXCEPT TO THE EXTENT THAT SUCH DISCLAIMERS ARE HELD TO BE LEGALLY INVALID.

Sun Microsystems, Inc. détient les droits de propriété intellectuelle relatifs à la technologie incorporée dans le produit qui est décrit dans ce document. En particulier, et ce sans limitation, ces droits de propriété intellectuelle peuvent inclure un ou plusieurs brevets américains ou des applications de brevet en attente aux Etats-Unis et dans d'autres pays.

Cette distribution peut comprendre des composants développés par des tierces personnes.

Certaines composants de ce produit peuvent être dérivées du logiciel Berkeley BSD, licenciés par l'Université de Californie. UNIX est une marque déposée aux Etats-Unis et dans d'autres pays; elle est licenciée exclusivement par X/Open Company, Ltd.

Sun, Sun Microsystems, le logo Sun, le logo Solaris, le logo Java Coffee Cup, docs.sun.com, Java et Solaris sont des marques de fabrique ou des marques déposées de Sun Microsystems, Inc. aux Etats-Unis et dans d'autres pays. Toutes les marques SPARC sont utilisées sous licence et sont des marques de fabrique ou des marques déposées de SPARC International, Inc. aux Etats-Unis et dans d'autres pays. Les produits portant les marques SPARC sont basés sur une architecture développée par Sun Microsystems, Inc.

L'interface d'utilisation graphique OPEN LOOK et Sun a été développée par Sun Microsystems, Inc. pour ses utilisateurs et licenciés. Sun reconnaît les efforts de pionniers de Xerox pour la recherche et le développement du concept des interfaces d'utilisation visuelle ou graphique pour l'industrie de l'informatique. Sun détient une licence non exclusive de Xerox sur l'interface d'utilisation graphique Xerox, cette licence couvrant également les licenciés de Sun qui mettent en place l'interface d'utilisation graphique OPEN LOOK et qui, en outre, se conforment aux licences écrites de Sun.

Les produits qui font l'objet de cette publication et les informations qu'il contient sont régis par la legislation américaine en matière de contrôle des exportations et peuvent être soumis au droit d'autres pays dans le domaine des exportations et importations. Les utilisations finales, ou utilisateurs finaux, pour des armes nucléaires, des missiles, des armes chimiques ou biologiques ou pour le nucléaire maritime, directement ou indirectement, sont strictement interdites. Les exportations ou réexportations vers des pays sous embargo des Etats-Unis, ou vers des entités figurant sur les listes d'exclusion d'exportation américaines, y compris, mais de manière non exclusive, la liste de personnes qui font objet d'un ordre de ne pas participer, d'une façon directe ou indirecte, aux exportations des produits ou des services qui sont régis par la legislation américaine en matière de contrôle des exportations et la liste de ressortissants spécifiquement designés, sont rigoureusement interdites.

(3)

Working with Realms, Users, Groups, and Roles ... 777 What Are Realms, Users, Groups, and Roles? ... 778 Managing Users and Groups on the Application Server ... 781 Setting Up Security Roles ... 782 Mapping Roles to Users and Groups ... 784 Establishing a Secure Connection Using SSL ... 785 Installing and Configuring SSL Support ... 785 Specifying a Secure Connection in Your Application Deployment Descriptor ... 786 Verifying SSL Support ... 787 Working with Digital Certificates ... 788 Enabling Mutual Authentication over SSL ... 793 Further Information about Security ... 795

29 Securing Java EE Applications...797

Securing Enterprise Beans ... 798 Accessing an Enterprise Bean Caller’s Security Context ... 799 Declaring Security Role Names Referenced from Enterprise Bean Code ... 801 Defining a Security View of Enterprise Beans ... 804 Using Enterprise Bean Security Annotations ... 815 Using Enterprise Bean Security Deployment Descriptor Elements ... 816 Configuring IOR Security ... 817 Deploying Secure Enterprise Beans ... 819 Enterprise Bean Example Applications ... 820 Example: Securing an Enterprise Bean ... 820 Example: Using theisCallerInRoleandgetCallerPrincipalMethods ... 826 Discussion: Securing the Duke’s Bank Example ... 831 Securing Application Clients ... 832 Using Login Modules ... 832 Using Programmatic Login ... 833 Securing EIS Applications ... 834 Container-Managed Sign-On ... 834 Component-Managed Sign-On ... 834 Configuring Resource Adapter Security ... 835 Mapping an Application Principal to EIS Principals ... 837

(23)

30 Securing Web Applications...839 Overview of Web Application Security ... 840 Working with Security Roles ... 841 Declaring Security Roles ... 841 Mapping Security Roles to Application Server Groups ... 844 Checking Caller Identity Programmatically ... 845 Declaring and Linking Role References ... 846 Defining Security Requirements for Web Applications ... 848 Declaring Security Requirements Using Annotations ... 849 Declaring Security Requirements in a Deployment Descriptor ... 851 Specifying a Secure Connection ... 857 Specifying an Authentication Mechanism ... 858 Examples: Securing Web Applications ... 867 Example: Using Form-Based Authentication with a JSP Page ... 868 Example: Basic Authentication with a Servlet ... 877 Example: Basic Authentication with JAX-WS ... 885

31 The Java Message Service API... 893

Overview of the JMS API ... 893 What Is Messaging? ... 893 What Is the JMS API? ... 894 When Can You Use the JMS API? ... 894 How Does the JMS API Work with the Java EE Platform? ... 896 Basic JMS API Concepts ... 896 JMS API Architecture ... 897 Messaging Domains ... 898 Message Consumption ... 900 The JMS API Programming Model ... 900 JMS Administered Objects ... 901 JMS Connections ... 903 JMS Sessions ... 904 JMS Message Producers ... 904 JMS Message Consumers ... 905 JMS Messages ... 907 JMS Queue Browsers ... 909

(24)

JMS Exception Handling ... 910 Writing Simple JMS Client Applications ... 911 A Simple Example of Synchronous Message Receives ... 911 A Simple Example of Asynchronous Message Consumption ... 920 A Simple Example of Browsing Messages in a Queue ... 926 Running JMS Client Programs on Multiple Systems ... 931 Creating Robust JMS Applications ... 935 Using Basic Reliability Mechanisms ... 936 Using Advanced Reliability Mechanisms ... 942 Using the JMS API in a Java EE Application ... 954 Using@ResourceAnnotations in Java EE Components ... 954 Using Session Beans to Produce and to Synchronously Receive Messages ... 955 Using Message-Driven Beans to Receive Messages Asynchronously ... 956 Managing Distributed Transactions ... 958 Using the JMS API with Application Clients and Web Components ... 960 Further Information about JMS ... 961

32 Java EE Examples Using the JMS API... 963

A Java EE Application That Uses the JMS API with a Session Bean ... 964 Writing the Application Components for theclientsessionmdbExample ... 964 Creating Resources for theclientsessionmdbExample ... 967 Building, Deploying, and Running theclientsessionmdbExample Using NetBeans IDE ... 967 Building, Deploying, and Running theclientsessionmdbExample Using Ant ... 969 A Java EE Application That Uses the JMS API with an Entity ... 970 Overview of theclientmdbentityExample Application ... 970 Writing the Application Components for theclientmdbentityExample ... 972 Creating Resources for theclientmdbentityExample ... 974 Building, Deploying, and Running theclientmdbentityExample Using NetBeans IDE ... 975 Building, Deploying, and Running theclientmdbentityExample Using Ant ... 977 An Application Example That Consumes Messages from a Remote Server ... 979 Overview of theconsumeremoteExample Modules ... 979 Writing the Module Components for theconsumeremoteExample ... 980 Creating Resources for theconsumeremoteExample ... 981 Using Two Application Servers for theconsumeremoteExample ... 981

(25)

Building, Deploying, and Running theconsumeremoteModules Using NetBeans IDE ... 982 Building, Deploying, and Running theconsumeremoteModules Using Ant ... 983 An Application Example That Deploys a Message-Driven Bean on Two Servers ... 985 Overview of thesendremoteExample Modules ... 986 Writing the Module Components for thesendremoteExample ... 987 Creating Resources for thesendremoteExample ... 988 Using Two Application Servers for thesendremoteExample ... 989 Building, Deploying, and Running thesendremoteModules Using NetBeans IDE ... 989 Building, Deploying, and Running thesendremoteModules Using Ant ... 992

33 Transactions... 997

What Is a Transaction? ... 997 Container-Managed Transactions ... 998 Transaction Attributes ... 998 Rolling Back a Container-Managed Transaction ... 1002 Synchronizing a Session Bean’s Instance Variables ... 1002 Methods Not Allowed in Container-Managed Transactions ... 1003 Bean-Managed Transactions ... 1003 JTA Transactions ... 1004 Returning without Committing ... 1004 Methods Not Allowed in Bean-Managed Transactions ... 1005 Transaction Timeouts ... 1005 Updating Multiple Databases ... 1005 Transactions in Web Components ... 1007

34 Resource Connections ... 1009

Resources and JNDI Naming ... 1009

DataSourceObjects and Connection Pools ... 1010 Resource Injection ... 1011 Field-Based Injection ... 1012 Method-Based Injection ... 1013 Class-Based Injection ... 1014 TheconfirmerExample Application ... 1014 Running theconfirmerExample Application ... 1015 Further Information about Resources ... 1018

(26)

35 Connector Architecture... 1019 About Resource Adapters ... 1019 Resource Adapter Contracts ... 1021 Management Contracts ... 1021 Outbound Contracts ... 1022 Inbound Contracts ... 1023 Common Client Interface ... 1023 Further Information about the Connector Architecture ... 1025

Part VII Case Studies...1027

36 The Coffee Break Application...1029

Overview of the Coffee Break Application ... 1029 Common Code ... 1031 JAX-WS Coffee Supplier Service ... 1031 Service Implementation ... 1031 SAAJ Coffee Supplier Service ... 1032 SAAJ Client ... 1033 SAAJ Service ... 1040 Coffee Break Server ... 1046 JSP Pages ... 1046 JavaBeans Components ... 1048 TheRetailPriceListServletServlet ... 1050 Resource Configuration ... 1050 Building, Packaging, Deploying, and Running the Coffee Break Application ... 1051 Setting the Port ... 1052 Building, Packaging, and Deploying the JAX-WS Coffee Supplier Service ... 1052 Building, Packaging, and Deploying the SAAJ Coffee Supplier Service ... 1053 Building, Packaging, and Deploying the Coffee Break Server ... 1053 Running the Coffee Break Client ... 1054 Removing the Coffee Break Application ... 1056

37 The Duke’s Bank Application...1057

Overview of the Duke’s Bank Application ... 1057

(27)

Enterprise Beans ... 1058 Session Beans ... 1059 Java Persistence Entities ... 1061 Helper Classes ... 1061 Database Tables ... 1062 Protecting the Enterprise Beans ... 1063 Application Client ... 1064 The Classes and Their Relationships ... 1065

BankAdminClass ... 1065 Web Client ... 1066 Design Strategies ... 1068 Client Components ... 1069 Request Processing ... 1071 Protecting the Web Client Resources ... 1073 Building, Packaging, Deploying, and Running the Duke's Bank Application ... 1075 Setting Up the Servers ... 1075 Building, Packaging, and Deploying Duke’s Bank Using NetBeans IDE ... 1076 Building, Packaging, and Deploying Duke’s Bank Using Ant ... 1077 Running the Duke's Bank Application Client Using NetBeans IDE ... 1077 Running the Duke's Bank Application Client Using Ant ... 1077 Running the Duke's Bank Web Client ... 1078

Part VIII Appendixes...1081

A Java Encoding Schemes...1083

Further Information about Character Encoding ... 1084

B Preparation for Java EE Certification Exams... 1085

CX-310-081: Sun Certified Web Component Developer ... 1086 SL-351–EE5: Business Component Development with Enterprise JavaBeans Technology .. 1086

C About the Authors...1089

Index... 1091

(28)

(29)

Preface

This tutorial is a guide to developing enterprise applications for the JavaTM

Platform, Enterprise Edition 5 (Java EE 5).

This preface contains information about and conventions for the entire Sun Java System Application Server documentation set.

Before You Read This Book

Before proceeding with this tutorial, you should have a good knowledge of the Java

programming language. A good way to get to that point is to work throughThe Java Tutorial,

Fourth Edition, Sharon Zakhour et al. (Addison-Wesley, 2006). You should also be familiar with the Java DataBase Connectivity (JDBCTM

) and relational database features described inJDBC API Tutorial and Reference, Third Edition, Maydene Fisher et al. (Addison-Wesley, 2003).

How This Book Is Organized

The Java EE 5 platform is quite large, and this tutorial reflects this. However, you don’t have to digest everything in it at once. The tutorial has been divided into parts to help you navigate the content more easily.

This tutorial opens with an introductory chapter, which you should read before proceeding to any specific technology area.Chapter 1, “Overview”covers the Java EE 5 platform architecture and APIs, the Sun Java System Application Server 9.1, and how to use the this tutorial's examples.

When you have digested the basics, you can delve into one or more of the five main technology areas listed next. Because there are dependencies between some of the chapters,Figure P–1

contains a roadmap for navigating through the tutorial.

■ The web-tier technology chapters inPart IIcover the components used in developing the

presentation layer of a Java EE 5 or stand-alone web application:

■ Java Servlet

■ JavaServer PagesTM(JSPTM)

(30)

■ JavaServerTMFaces

■ Web application internationalization and localization

■ The web services technology chapters inPart IIIcover the APIs used in developing standard

web services:

■ The Java API for XML-based Web Services (JAX-WS) ■ The Java API for XML Binding (JAXB)

■ The Streaming API for XML (StAX)

■ The SOAP with Attachments API for JavaTM(SAAJ)

■ The Enterprise JavaBeansTM(EJBTM) technology chapters inPart IVcover the components

used in developing the business logic of a Java EE 5 application:

■ Session beans ■ Message-driven beans

■ The persistence technology chapters inPart Vcover the Java Persistence API, which is used

for accessing databases from Java EE applications:

■ Introduction to the Java Persistence API ■ Persistence in the Web Tier

■ Persistence in the EJB Tier

■ The Java Persistence Query Language

■ The platform services chapters inPart VIcover the system services used by all the Java EE 5

component technologies:

■ Security

■ Java Message Service ■ Transactions

■ Resource connections

(31)

After you have become familiar with some of the technology areas, you are ready to tackle the case studies inPart VII, which tie together several of the technologies discussed in the tutorial. The Coffee Break Application describes an application that uses the web application and web services APIs. The Duke’s Bank Application describes an application that employs web application technologies, enterprise beans, and the Java Persistence API.

Finally,Part VIIIcontains information about Java encoding schemes and Java EE certification that may be helpful to the Java EE 5 application developer, and information about the tutorial's authors.

Overview (1)

Getting Started with Web Applications (3)

Building Web Services with

JAX-WS (16)

Enterprise Beans (20-23)

Security (28-30)

SAAJ (19) JAXB (17)

Coffee Break Case Study (36) Servlets (4)

JSP (5-9)

JSF (10-14)

l18n and L10n (15)

Duke’s Bank Case Study (37)

JMS (31-32)

Transactions (33)

Resource Connections

(34) STAX (18)

Connectors (35)

Persistence (24-27)

Using the Tutorial Examples

(2)

FIGURE P–1 Roadmap to This Tutorial

(32)

Application Server Documentation Set

The Application Server documentation set describes deployment planning and system installation. The Uniform Resource Locator (URL) for Application Server documentation is

http://docs.sun.com/coll/1343.4. For an introduction to Application Server, refer to the books in the order in which they are listed in the following table.

TABLE P–1 Books in the Application Server Documentation Set

Book Title Description

Documentation Center Application Server documentation topics organized by task and subject.

Release Notes Late-breaking information about the software and the documentation. Includes a comprehensive, table-based summary of the supported hardware, operating system, Java Development Kit (JDKTM_{), and database drivers.}

Quick Start Guide How to get started with the Application Server product.

Installation Guide Installing the software and its components.

Deployment Planning Guide Evaluating your system needs and enterprise to ensure that you deploy the Application Server in a manner that best suits your site. General issues and concerns that you must be aware of when deploying the server are also discussed.

Application Deployment Guide Deployment of applications and application components to the Application Server. Includes information about deployment descriptors.

Developer’s Guide Creating and implementing Java Platform, Enterprise Edition (Java EE platform) applications intended to run on the Application Server that follow the open Java standards model for Java EE components and APIs. Includes information about developer tools, security, debugging, and creating lifecycle modules.

Java EE 5 Tutorial Using Java EE 5 platform technologies and APIs to develop Java EE applications.

Java WSIT Tutorial Developing web applications using the Web Service Interoperability Technologies (WSIT). Describes how, when, and why to use the WSIT technologies and the features and options that each technology supports.

Administration Guide System administration for the Application Server, including configuration, monitoring, security, resource management, and web services management.

High Availability Administration Guide

Post-installation configuration and administration instructions for the high-availability database.

Administration Reference Editing the Application Server configuration file,domain.xml.

Upgrade and Migration Guide Upgrading from an older version of Application Server or migrating Java EE applications from competitive application servers. This guide also describes differences between adjacent product releases and configuration options that can result in incompatibility with the product specifications.

(33)

TABLE P–1 Books in the Application Server Documentation Set (Continued)

Book Title Description

Performance Tuning Guide Tuning the Application Server to improve performance.

Troubleshooting Guide Solving Application Server problems.

Error Message Reference Solving Application Server error messages.

Reference Manual Utility commands available with the Application Server; written in man page style. Includes theasadmincommand line interface.

Default Paths and File Names

The following table describes the default paths and file names that are used in this book.

TABLE P–2 Default Paths and File Names

Placeholder Description Default Value

tut-install Represents the base installation directory for the Java EE Tutorial.

None. Install the tutorial in a directory without spaces in the path.

java-home Represents the base installation directory for the Java Platform, Standard Edition (Java SE platform).

None. Same value as theJAVA_HOMEenvironment variable.

as-install Represents the base installation directory for the Application Server or the Software Development Kit (SDK) of which the Application Server is a part.

Java ES installations on the SolarisTM

operating system:

/opt/SUNWappserver/appserver

Java ES installations on the Linux operating system:

/opt/sun/appserver/

Other Solaris and Linux non-SDK installations, non-root user:

user’s-home-directory/SUNWappserver

Other Solaris and Linux non-SDK installations, root user:

/opt/SUNWappserver

Solaris and Linux SDK installations:

user’s-home-directory/SDK

Windows, all non-SDK installations:

SystemDrive:\Sun\AppServer

Windows, all SDK installations:

SystemDrive:\Sun\SDK

domain-root-dir Represents the directory containing all Application Server domains.

Java ES Solaris installations:

/var/opt/SUNWappserver/domains/

Java ES Linux installations:

/var/opt/sun/appserver/domains/

All other installations:

(35)

TABLE P–2 Default Paths and File Names (Continued)

Placeholder Description Default Value

domain-dir Represents the directory for a domain.

In configuration files, you might see domain-dirrepresented as follows:

${com.sun.aas.instanceRoot}

domain-root-dir/domain-dir

instance-dir Represents the directory for a server instance. domain-dir/instance-dir

Typographic Conventions

The following table describes the typographic changes that are used in this book.

TABLE P–3 Typographic Conventions

Typeface Meaning Example

AaBbCc123 The names of commands, files, and directories, and onscreen computer output

Edit your.loginfile.

Usels -ato list all files.

machine_name% you have mail.

AaBbCc123 What you type, contrasted with onscreen computer output

machine_name%su

Password:

AaBbCc123 A placeholder to be replaced with a real name or value

The command to remove a file isrmfilename.

AaBbCc123 Book titles, new terms, and terms to be emphasized (note that some emphasized items appear bold online)

Read Chapter 6 in theUser's Guide.

Acacheis a copy that is stored locally.

Donotsave the file.

Symbol Conventions

The following table explains symbols that might be used in this book.

TABLE P–4 Symbol Conventions

Symbol Description Example Meaning

[ ] Contains optional arguments and command options.

(36)

TABLE P–4 Symbol Conventions (Continued)

Symbol Description Example Meaning

{ | } Contains a set of choices for a required command option.

-d {y|n} The-doption requires that you use either theyargument or then argument.

${ } Indicates a variable reference.

${com.sun.javaRoot} References the value of the com.sun.javaRootvariable.

- Joins simultaneous multiple keystrokes.

Control-A Press the Control key while you press the A key.

+ Joins consecutive multiple keystrokes.

Ctrl+A+N Press the Control key, release it, and then press the subsequent keys.

→ Indicates menu item

selection in a graphical user interface.

File→New→Templates From the File menu, choose New.

From the New submenu, choose Templates.

Documentation, Support, and Training

The Sun web site provides information about the following additional resources:

■ Documentation (http://www.sun.com/documentation/)

■ Support (http://www.sun.com/support/)

■ Training (http://www.sun.com/training/)

Searching Sun Product Documentation

Besides searching Sun product documentation from the docs.sun.comSM

web site, you can use a search engine by typing the following syntax in the search field:

search-term site:docs.sun.com

For example, to search for “broker,” type the following:

broker site:docs.sun.com

To include other Sun web sites in your search (for example,java.sun.com,www.sun.com, and

developers.sun.com), usesun.comin place ofdocs.sun.comin the search field.

(37)

Third-Party Web Site References

Third-party URLs are referenced in this document and provide additional, related information.

Note –Sun is not responsible for the availability of third-party web sites mentioned in this document. Sun does not endorse and is not responsible or liable for any content, advertising, products, or other materials that are available on or through such sites or resources. Sun will not be responsible or liable for any actual or alleged damage or loss caused or alleged to be caused by or in connection with use of or reliance on any such content, goods, or services that are available on or through such sites or resources.

Sun Welcomes Your Comments

Sun is interested in improving its documentation and welcomes your comments and

suggestions. To share your comments, go tohttp://docs.sun.comand click Send Comments. In the online form, provide the full document title and part number. The part number is a 7-digit or 9-digit number that can be found on the book's title page or in the document's URL. For example, the part number of this book is 819-3669.

(38)

(39)

Introduction

Part One introduces the tutorial and examples.

(40)

(41)

Overview

Developers today increasingly recognize the need for distributed, transactional, and portable applications that leverage the speed, security, and reliability of server-side technology. In the world of information technology, enterprise applications must be designed, built, and produced for less money, with greater speed, and with fewer resources.

With the JavaTM

Platform, Enterprise Edition (Java EE), development of Java enterprise applications has never been easier or faster. The aim of the Java EE 5 platform is to provide developers a powerful set of APIs while reducing development time, reducing application complexity, and improving application performance.

The Java EE 5 platform introduces a simplified programming model. With Java EE 5 technology, XML deployment descriptors are now optional. Instead, a developer can simply enter the information as an annotation directly into a Java source file, and the Java EE server will configure the component at deployment and runtime. These annotations are generally used to embed in a program data that would otherwise be furnished in a deployment descriptor. With annotations, the specification information is put directly in your code next to the program element that it affects.

In the Java EE platform, dependency injection can be applied to all resources that a component needs, effectively hiding the creation and lookup of resources from application code.

Dependency injection can be used in EJB containers, web containers, and application clients. Dependency injection allows the Java EE container to automatically insert references to other required components or resources using annotations.

The Java Persistence API is new to the Java EE 5 platform. The Java Persistence API provides an object/relational mapping for managing relational data in enterprise beans, web components, and application clients. It can also be used in Java SE applications, outside of the Java EE environment.

This tutorial uses examples to describe the features and functionalities available in the Java EE 5 platform for developing enterprise applications. Whether you are a new or experienced Enterprise developer, you should find the examples and accompanying text a valuable and accessible knowledge base for creating your own solutions.

1

(42)

If you are new to Java EE enterprise application development, this chapter is a good place to start. Here you will review development basics, learn about the Java EE architecture and APIs, become acquainted with important terms and concepts, and find out how to approach Java EE application programming, assembly, and deployment.

Java EE Application Model

The Java EE application model begins with the Java programming language and the Java virtual machine. The proven portability, security, and developer productivity they provide forms the basis of the application model. Java EE is designed to support applications that implement enterprise services for customers, employees, suppliers, partners, and others who make demands on or contributions to the enterprise. Such applications are inherently complex, potentially accessing data from a variety of sources and distributing applications to a variety of clients.

To better control and manage these applications, the business functions to support these various users are conducted in the middle tier. The middle tier represents an environment that is closely controlled by an enterprise’s information technology department. The middle tier is typically run on dedicated server hardware and has access to the full services of the enterprise.

The Java EE application model defines an architecture for implementing services as multitier applications that deliver the scalability, accessibility, and manageability needed by

enterprise-level applications. This model partitions the work needed to implement a multitier service into two parts: the business and presentation logic to be implemented by the developer, and the standard system services provided by the Java EE platform. The developer can rely on the platform to provide solutions for the hard systems-level problems of developing a multitier service.

Distributed Multitiered Applications

The Java EE platform uses a distributed multitiered application model for enterprise applications. Application logic is divided into components according to function, and the various application components that make up a Java EE application are installed on different machines depending on the tier in the multitiered Java EE environment to which the application component belongs.

Figure 1–1shows two multitiered Java EE applications divided into the tiers described in the following list. The Java EE application parts shown inFigure 1–1are presented in“Java EE Components” on page 44.

(43)

■ Enterprise information system (EIS)-tier software runs on the EIS server.

Although a Java EE application can consist of the three or four tiers shown inFigure 1–1, Java EE multitiered applications are generally considered to be three-tiered applications because they are distributed over three locations: client machines, the Java EE server machine, and the database or legacy machines at the back end. Three-tiered applications that run in this way extend the standard two-tiered client and server model by placing a multithreaded application server between the client application and back-end storage.

Security

While other enterprise application models require platform-specific security measures in each application, the Java EE security environment enables security constraints to be defined at deployment time. The Java EE platform makes applications portable to a wide variety of security implementations by shielding application developers from the complexity of implementing security features.

The Java EE platform provides standard declarative access control rules that are defined by the developer and interpreted when the application is deployed on the server. Java EE also provides

Application Client

Java EE Application 1 Java EE Application 2

Dynamic HTML Pages

Web Tier

Business Tier

Enterprise Beans Enterprise Beans

Database Database

JSP Pages

EIS Tier

Client Tier Client_Machine

Java EE Server

Database Server

FIGURE 1–1 Multitiered Applications

(44)

standard login mechanisms so application developers do not have to implement these mechanisms in their applications. The same application works in a variety of different security environments without changing the source code.

Java EE Components

Java EE applications are made up of components. AJava EE componentis a self-contained functional software unit that is assembled into a Java EE application with its related classes and files and that communicates with other components.

The Java EE specification defines the following Java EE components:

■ Application clients and applets are components that run on the client.

■ Java Servlet, JavaServer Faces, and JavaServer PagesTM(JSPTM) technology components are

web components that run on the server.

■ Enterprise JavaBeansTM(EJBTM) components (enterprise beans) are business components

that run on the server.

Java EE components are written in the Java programming language and are compiled in the same way as any program in the language. The difference between Java EE components and “standard” Java classes is that Java EE components are assembled into a Java EE application, are verified to be well formed and in compliance with the Java EE specification, and are deployed to production, where they are run and managed by the Java EE server.

Java EE Clients

A Java EE client can be a web client or an application client.

Web Clients

Aweb clientconsists of two parts: (1) dynamic web pages containing various types of markup language (HTML, XML, and so on), which are generated by web components running in the web tier, and (2) a web browser, which renders the pages received from the server.

A web client is sometimes called athin client. Thin clients usually do not query databases, execute complex business rules, or connect to legacy applications. When you use a thin client, such heavyweight operations are off-loaded to enterprise beans executing on the Java EE server, where they can leverage the security, speed, services, and reliability of Java EE server-side technologies.

(45)

Applets

A web page received from the web tier can include an embedded applet. Anappletis a small client application written in the Java programming language that executes in the Java virtual machine installed in the web browser. However, client systems will likely need the Java Plug-in and possibly a security policy file for the applet to successfully execute in the web browser.

Web components are the preferred API for creating a web client program because no plug-ins or security policy files are needed on the client systems. Also, web components enable cleaner and more modular application design because they provide a way to separate applications programming from web page design. Personnel involved in web page design thus do not need to understand Java programming language syntax to do their jobs.

Application Clients

Anapplication clientruns on a client machine and provides a way for users to handle tasks that require a richer user interface than can be provided by a markup language. It typically has a graphical user interface (GUI) created from the Swing or the Abstract Window Toolkit (AWT) API, but a command-line interface is certainly possible.

Application clients directly access enterprise beans running in the business tier. However, if application requirements warrant it, an application client can open an HTTP connection to establish communication with a servlet running in the web tier. Application clients written in languages other than Java can interact with Java EE 5 servers, enabling the Java EE 5 platform to interoperate with legacy systems, clients, and non-Java languages.

The JavaBeans

TM

Component Architecture

The server and client tiers might also include components based on the JavaBeans component architecture (JavaBeans components) to manage the data flow between an application client or applet and components running on the Java EE server, or between server components and a database. JavaBeans components are not considered Java EE components by the Java EE specification.

JavaBeans components have properties and havegetandsetmethods for accessing the properties. JavaBeans components used in this way are typically simple in design and implementation but should conform to the naming and design conventions outlined in the JavaBeans component architecture.

Java EE Server Communications

Figure 1–2shows the various elements that can make up the client tier. The client

communicates with the business tier running on the Java EE server either directly or, as in the case of a client running in a browser, by going through JSP pages or servlets running in the web tier.

(46)

Your Java EE application uses a thin browser-based client or thick application client. In deciding which one to use, you should be aware of the trade-offs between keeping functionality on the client and close to the user (thick client) and off-loading as much functionality as possible to the server (thin client). The more functionality you off-load to the server, the easier it is to distribute, deploy, and manage the application; however, keeping more functionality on the client can make for a better perceived user experience.

Web Components

Java EE web components are either servlets or pages created using JSP technology (JSP pages) and/or JavaServer Faces technology.Servletsare Java programming language classes that dynamically process requests and construct responses.JSP pagesare text-based documents that execute as servlets but allow a more natural approach to creating static content.JavaServer Faces

technology builds on servlets and JSP technology and provides a user interface component framework for web applications.

Web Tier

Business Tier

Client Tier

Java EE Server > Web Browser, Web Pages,

Applets, and Optional JavaBeans Components > Application Client and

Optional JavaBeans Components

(47)

Static HTML pages and applets are bundled with web components during application assembly but are not considered web components by the Java EE specification. Server-side utility classes can also be bundled with web components and, like HTML pages, are not considered web components.

As shown inFigure 1–3, the web tier, like the client tier, might include a JavaBeans component to manage the user input and send that input to enterprise beans running in the business tier for processing.

Business Components

Business code, which is logic that solves or meets the needs of a particular business domain such as banking, retail, or finance, is handled by enterprise beans running in the business tier.

Figure 1–4shows how an enterprise bean receives data from client programs, processes it (if necessary), and sends it to the enterprise information system tier for storage. An enterprise bean also retrieves data from storage, processes it (if necessary), and sends it back to the client program.

Web Tier

Business Tier

Client Tier

Java EE Server > Web Browser, Web Pages,

Applets, and Optional JavaBeans Components > Application Client and

Optional JavaBeans Components

JavaBeans Components

(Optional)

JSP Pages Servlets

FIGURE 1–3 Web Tier and Java EE Applications

The Java EE 5 Tutorial