Microsoft PowerPoint - 《Java高级技术》第十二讲 JavaEE Overview.ppt

Transcription

1 Java 高级技术 课程 Java EE 概述 (1) 李戈 北京大学信息科学技术学院软件研究所 2008 年 5 月 17 日

2 Java technology What is Java EE is both a programming language and a platform. The Java programming language is a high-level object-oriented language that has a particular syntax and style. Java platform is a particular environment in which Java programming language applications run. There are three platforms of the Java programming language: Java Platform, Standard Edition (Java SE) Java Platform, Enterprise Edition (Java EE) Java Platform, Micro Edition (Java ME)

3 What is Java EE Java Platform, Standard Edition Java SE s API provides the core functionality of the Java programming language. It defines everything from the basic types and objects to high-level classes that are used for networking, security, database access, graphical user interface (GUI) development, and XML parsing. In addition to the core API, the Java SE platform consists of a virtual machine, development tools, deployment technologies, and other class libraries and toolkits commonly used in Java applications.

4 What is Java EE Java SE 6 Platform at a Glance

5 What is Java EE JavaME The JavaME platform provides an API and a small-footprint virtual machine for running Java programming language applications on small devices. The API is a subset of the Java SE API, along with special class libraries useful for small device application development. Java EE The Java EE platform is built on top of the Java SE platform. Java EE provides an API and runtime environment for developing and running large-scale, multi-tiered, scalable, reliable, and secure network applications.

6 Java EE What is Java EE provides a comprehensive and cohesive implementation for enterprise system needs. Elements in Enterprise system

7 What is Enterprise System Needs Information Presentation Web Content Presentation Applications Content Presentation Business Logic Web Connectivity Logic Enterprise Application Logic Data Management Enterprise Data Access Intra & Inter Applications Intra-Enterprise Applications Legacy Auxiliary Embedded External Inter-Enterprise Applications Communications Distributed Enterprise Communications

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9 领域工程 领域工程方法 领域专家 领域模型 / 构架 最终用户 应用应用应用应用 领域 输入 领域工程 输出 A1 D B1 应用系统开发 C1 A2 领域分析员 B2 领域可复用构件 需求分析员 软件设计者...

10 Enterprise System Solution

11 JavaEE Enterprise System Solution Model

12 Java EE Application Model The Java EE platform uses a distributed multi-tiered application model for enterprise applications.

13 JavaEE Component-Container Architecture An enterprise component is an encapsulation of a certain body of code utilized in an enterprise application. An enterprise container represents an environment in which a component operates. The container itself may offer a set of services that components may tap in a standard fashion.

14 JavaEE Components & Containers

15 J2EE Components & Containers Five & Four defined within the J2EE specification. Five major classes of components : EJB Component / JSP Web Component / Servlet Component / Applet / Java Application Four container types : Enterprise JavaBeans (EJB) container / Web container / Application client container / Applet container

16 Java EE Clients Client Tier Web Clients (Web Pages + Web Browser) /Applets + JavaBeans Components Web Pages: various types of markup language (HTML, XML, and so on), which are generated by web components running in the web tier Application Clients + JavaBeans Components

17 Web Tier Server Tier (1) Java EE web components ( Servlets & JSP pages) JavaBeans component

18 Web Tier Server Tier (1) Java EE web components Servlets are Java programming language classes that dynamically process requests and construct responses. JSP pages are 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. JavaBeans component manage the user input and send that input to enterprise beans running in the business tier for processing.

19 Business Tier Server Tier (2) Business Components (Enterprise Java Bean)

20 Business Tier Server Tier (2) Business Components (Enterprise Java Bean) receives data from client programs, processes it (if necessary), and sends it to the enterprise information system tier for storage. retrieves data from storage, processes it (if necessary), and sends it back to the client program.

21 EIS Tier Enterprise Information System Tier Database Systems Enterprise Resource Planning (ERP) some Legacy Information Systems

22 Containers Java EE Containers Business logic is organized into reusable components Java EE server provides underlying services in the form of a container for components. Containers are the interface between a component and the lowlevel platform-specific functionality that supports the component.

23 Services for JavaEE Java EE 5 Services

24 Java Transaction API (JTA) Java EE 5 Services The Java Transaction API provides a standard interface for demarcating transactions. provides a default auto commit to handle transaction commits and rollbacks. An auto commit means that any other applications that are viewing data will see the updated data after each database read or write operation. For example, your application performs two separate database access operations that depend on each other, you will want to use the JTA API to demarcate where the entire transaction, including both operations, begins, rolls back, and commits.

25 Java EE 5 Services JavaNaming and Directory InterfaceTM (JNDI) provides naming and directory functionality, enabling applications to access multiple naming and directory services, including existing naming and directory services such as LDAP, NDS, DNS, and NIS. It provides applications with methods for performing standard directory operations, such as searching for objects using their attributes. Using JNDI, a Java EE application can store and retrieve any type of named Java object, allowing Java EE applications to coexist with many legacy applications and systems.

26 Java EE 5 Services Java API for XML Processing (JAXP) A part of the Java SE platform supports the processing of XML documents using Document Object Model (DOM), Simple API for XML (SAX), and Extensible Stylesheet Language Transformations (XSLT). enables applications to parse and transform XML documents. enables using any XML-compliant parser or XSL processor from within your application.

27 Java EE 5 Services Java API for XML Web Services (JAX-WS) provides support for web services that use the JAXB API (Java Architecture for XML Binding) binding an XMLschema to XML binding XML data to Java objects. defines client APIs for accessing web services. support for message handlers that can process message requests and responses.

28 About Web Services

29 Java EE 5 Services Remote Method Invocation (RMI) allows an object running in one Java virtual machine to invoke methods on an object running in another Java virtual machine. RMI provides the mechanism by which the server and the client communicate and pass information back and forth. support for remote communication between programs RMI uses object serialization to marshal and unmarshal parameters and does not truncate types

30 Java EE 5 Services Common Object Request Broker Architecture (CORBA) CORBA implementation in the Java platform provides standards-based interoperability and connectivity. Java IDL enables distributed Web-enabled Java applications to transparently invoke operations on remote network services using the industry standard OMG IDL (Object Management Group Interface Definition Language) and IIOP (Internet Inter-ORB Protocol).

31 Java Message Service (JMS) Java EE 5 Services JMS defines the standard for reliable Enterprise Messaging. allows application components based on JavaEE to create, send, receive, and read messages. allowing loosely coupled, reliable, asynchronous interactions among JavaEE components and legacy systems capable of messaging.

32 Packaging Applications A Java EE application is delivered in an Enterprise Archive (EAR) file, a standard Java Archive(JAR) file with an.ear extension.

33 Java EE Modules in EAR The four types of Java EE modules are as follows: EJB modules, which contain class files for enterprise beans and an EJB deployment descriptor. Packaged as JAR files with a.jar extension. Web modules, which contain servlet class files, JSP files, supporting class files, GIF and HTML files, and a web application deployment descriptor. Packaged as JAR files with a.war extension. Application client modules, which contain class files and an application client deployment descriptor. Packaged as JAR files with a.jar extension. Resource adapter modules, which contain all Java interfaces, classes, native libraries, and other documentation, along with the resource adapter deployment descriptor. Packaged as JAR files with an.rar (resource adapter archive) extension.

34 Development Roles Java EE Product Provider Tool Provider Application Component Provider Enterprise Bean Developer Web ComponentDeveloper Application ClientDeveloper Application Assembler Application Deployer and Administrator

35 Java EE & Software Reuse 领域工程 软件再工程 软件构架 开放系统技术 软件过程 构件 构架获取 构件标准化与描述 构件分类 存储与检索 软件构件技术 构件组装 非技术因素 CASE 技术

36 软件复用 软件复用 出发点 : 在软件系统的开发中, 不再采用一切 从零开始 的模式, 而是以已有的工作为基础, 充分利用过去应用系统开发中积累的知识和经验 重点关注应用的特殊性, 开发应用的特有构成成分 软件复用 重复使用 为了复用目的而设计的软件 的过程 软件复用是必然 实践证明, 软件复用是解决软件危机, 提高软件生产效率和软件产品质量的现实可行的途径

37 软件构件 软件构件 (Software Component) 应用系统中具有相对独立性, 且可以明确辨识的构成成分 可复用构件 (Reusable Component) 应用系统中具有相对独立的功能和可复用价值的构件

38 对构件概念的理解 狭义的构件 软件系统中具有相对独立功能 可以明确辨识 接口由契约指定 和语境有明显依赖关系 可独立部署 且多由第三方提供的可组装软件实体 既包括以 EJB,COM/DCOM,ActiveX,Web Services 等形式存在的可运行二进制程序, 也包括经过封装的源代码程序 广义的构件 随着对软件复用理解的不断深入, 软件构件概念的外延也在扩展 从构件实体到需求规约 系统构架 设计文档 测试案例等各种具有复用价值的软件资源都可称为构件

39 基于构件的软件开发 CBSD Component Based Software Development 软件复用的有效途径 重复使用 为复用目的而开发的软件构件 生产模式 : 从传统的软件编码工作转换为以软件构件为基础的系统集成组装 软件工业化生产的必然 传统工业 : 汽车 船舶 飞机工业的生产方式 软件的复杂性 构造性 演化性使之成为必然

40 好好想想, 有没有问题? 谢谢!