【文章內(nèi)容簡(jiǎn)介】 ftware Nanjing University 24 摘要 ? More about RMI ? J2EE/EJB 2022/8/15 Institute of Computer Software Nanjing University 25 J2EE ? JDBC ? JNDI ? EJB ? RMI ? Java IDL/CORBA ? JSP ? Java Servlet 2022/8/15 Institute of Computer Software Nanjing University 26 ? XML ? JMS ? JTA ? JavaMail ? JAF Application Servers ? The Multi tier applications have several independent ponents ? An application server provides the infrastructure and services to run such applications ? Application server products can be separated into 3 categories: ? J2EEbased solutions ? NonJ2EE solutions (PHP, ColdFusion, Perl, etc.) ? And the Microsoft solution (ASP/COM and now .NET with , , C, etc.) 2022/8/15 Institute of Computer Software Nanjing University 27 J2EE Application Servers ? Major J2EE products: ?BEA WebLogic ?IBM WebSphere ?Borland AppServer ?Sun/Oracle GlassFish ?JBoss 2022/8/15 Institute of Computer Software Nanjing University 28 Web Server and Application Server 2022/8/15 Institute of Computer Software Nanjing University 29 Web Server (HTTP Server) App Server 1 App Server 2 Inter Browser HTTP(S) J2EE Multitier Model 2022/8/15 Institute of Computer Software Nanjing University 30 J2EE Application Scenarios ? Multitier typical application 2022/8/15 Institute of Computer Software Nanjing University 31 J2EE Application Scenarios ? Standalone client 2022/8/15 Institute of Computer Software Nanjing University 32 J2EE Application Scenarios ? Webcentric application 2022/8/15 Institute of Computer Software Nanjing University 33 J2EE Application Scenarios ? Businesstobusiness 2022/8/15 Institute of Computer Software Nanjing University 34 J2EE Architecture 2022/8/15 Institute of Computer Software Nanjing University 35 Now ? JEE 5 ? JEE 6 ?Homepage: e/tech/ 2022/8/15 Institute of Computer Software Nanjing University 36 Main technologies ? JavaServer Pages (JSP) ? Servlet ? Enterprise JavaBeans (EJB) ? JSPs, servlets and EJBs are application ponents 2022/8/15 Institute of Computer Software Nanjing University 37 JSP ? Used for web pages with dynamic content ? Processes HTTP requests (nonblocking callandreturn) ? Accepts HTML tags, special JSP tags, and scriptlets of Java code ? Separates static content from presentation logic ? Can be created by web designer using HTML tools 2022/8/15 Institute of Computer Software Nanjing University 38 Servlet ? Used for web pages with dynamic content ? Processes HTTP requests (nonblocking callandreturn) ? Written in Java。 uses print statements to render HTML ? Loaded into memory once and then called many times ? Provides APIs for session management 2022/8/15 Institute of Computer Software Nanjing University 39 EJB ? EJBs are distributed ponents used to implement business logic (no UI) ? Developer concentrates on business logic ? Availability, scalability, security, interoperability and integrability handled by the J2EE server ? Client of EJBs can be JSPs, servlets, other EJBs and external aplications ? Clients see interfaces 2022/8/15 Institute of Computer Software Nanjing University 40 EJB ? EJB ? EJB ? EJB ? EJB ? EJB 2022/8/15 Institute of Computer Software Nanjing University 41 更簡(jiǎn)單 EJB技術(shù)要解決的問(wèn)題 ? EJB? 技術(shù)的初衷是簡(jiǎn)化企業(yè)級(jí)應(yīng)用的開(kāi)發(fā) ? 通過(guò) EJB容器環(huán)境 ?提供可共享的服務(wù)： ?Concurrency， Distribution, Transactions, ?EIS integration, Resource pooling, ?Security, Persistence ?提供 EJB運(yùn)行環(huán)境 ?減輕企業(yè)級(jí)應(yīng)用開(kāi)發(fā)人員的負(fù)擔(dān) 2022/8/15 Institute of Computer Software Nanjing University 42 EJB的相關(guān)概念 ? EJB容器：由廠商提供的位于 EJB服務(wù)器上的實(shí)體，管理 EJB的系統(tǒng)級(jí)服務(wù)，控制 EJB的生命周期。針對(duì)每一種組件，都有相應(yīng)的容器進(jìn)行處理。 ? EJB服務(wù)器：作為容器和低層平臺(tái)的橋梁管理著EJB容器和函數(shù)，向 EJB容器提供了訪問(wèn)系統(tǒng)服務(wù)的能力。 ? EJB接口 ()： Home接口， Remote接口， Local和 LocalHome接口 2022/8/15 Institute of Computer Software Nanjing University 43 EJB分類(lèi) ? Session Bean ?Stateless ?Stateful ? Entity Bean ? Message Driven Bean 2022/8/15 Institute of Computer Software Nanjing University 44 同步通信 異步通信 Session Bean ? Stateless session bean: ?Contains no userspecific data ?Business process that provides a generic service ?Container can pool stateless beans ?Example: shopping catalog 2022/8/15 Institute of Computer Software Nanjing University 45 Session Bean ?