【正文】 ponent。包括，開源的應(yīng)用服務(wù)器， JBoss 和 OnAS 在內(nèi)，已經(jīng)有多種 J2EE 應(yīng)用服務(wù)器已經(jīng)全部或者部分的實(shí)現(xiàn)了組件化。我們假設(shè)這種動(dòng)態(tài)的部署和拆卸服務(wù)存在于所有的兼容的 J2EE 服務(wù)器上而且在不理解類重載相關(guān)問題時(shí)一個(gè)健壯的類重載結(jié)結(jié)構(gòu)的應(yīng)用服務(wù)器就能夠重復(fù)的部署生命周期。這種本地部署所關(guān)心的不是在分布式架構(gòu)中去表現(xiàn)而是去增強(qiáng)一致性。 (2) 創(chuàng)建和綁定特定的 JNDI 目標(biāo)去訪問消息目的和數(shù)據(jù)源的能力 。 (3) 用組件的命名服務(wù)去綁定目標(biāo)。 在前兩個(gè) 實(shí)例中，應(yīng)用組件的開發(fā)者不僅書寫執(zhí)行在組件的運(yùn)行時(shí) JNDI 環(huán)境中的對(duì)象目錄代碼，而且書寫發(fā)布方法調(diào)用，與遠(yuǎn)程的組件相互發(fā)送和接受消息。例如， EJB 開發(fā)者可以選擇明確的事務(wù)區(qū)分方式，這種方式意味著開發(fā)者假設(shè)通過定義良好接口的事務(wù)經(jīng)理服務(wù)平臺(tái)來書寫明確的程序交互。 EJB 和 Web 組件被部署在由應(yīng)用服務(wù)贊助商提供的容器中 .它們有定義良好的容器規(guī)則來管理生命周期，線程，持久化和其他問題。最近名單上有多出了新的 Apache project Geronimo。資源適配器在 Java 連結(jié)結(jié)構(gòu)中被定義。在 Java 虛擬機(jī)調(diào)用或者異步的消息傳遞，取決與 EJB 組件的類型?？蛻舳税g覽器， applets， Java 應(yīng)用程序等和負(fù)責(zé)和服務(wù)器端的表現(xiàn)層或者業(yè)務(wù)層進(jìn)行交互。 (2) 組件和主服務(wù)器的鏈接 。 2 J2EE 背景知識(shí) 介紹 組件框架。這種架構(gòu)實(shí)現(xiàn)利用了 JBoss的可擴(kuò)展的微內(nèi)核結(jié)構(gòu)，基于 JMX規(guī)范。 在本論文中，我們提出自動(dòng)動(dòng)態(tài)部署 J2EE 應(yīng)用程序的框架涉及了上面的所有問題，這種框架為組件定義了結(jié)構(gòu)描述語言，鏈接說明和集合。這種需要對(duì)于哪怕在單一的應(yīng)用程序服務(wù)器上嘗試布置 J2EE 應(yīng)用的人來說也顯而易見，這種任務(wù)設(shè)計(jì)到大量的系統(tǒng)服務(wù)和應(yīng)用組件的配置。最近的著作已經(jīng)表明在廣域網(wǎng)中利用垂直負(fù)荷而不引起前面所述的 超時(shí)問題的可行性。 關(guān)鍵詞： j2ee； 動(dòng)態(tài)配置 ； 分布式 ； 組件 ； 1 前言 近幾年，我們已經(jīng)看到 基于組件的企業(yè)應(yīng)用開發(fā)的顯著 增加。 (5) 新的請(qǐng)求路徑可以復(fù)用先前的組件配置路徑 。 (3) 提供簡單但可表達(dá)的抽象 方法 去控制通過部署和拆卸組件獲得的適 用 性。組件配置過程評(píng)估了應(yīng)用程序路徑的正確性，確認(rèn)在系統(tǒng)組件上的應(yīng)用組件的獨(dú)立性和完成復(fù)制組件的部署。第 3 部分對(duì)這種架構(gòu)給出 了一般性的描述?，F(xiàn)在工業(yè)上的組件框架標(biāo)準(zhǔn)以對(duì)象管理組的CORBA 組件模型， SUN 公司的 JAVA 2 Platform J 企業(yè)版 [J2EE]和微軟公司的 .NET 標(biāo)準(zhǔn)，其中在企業(yè)里應(yīng)用最為廣泛的組件框架是 2EEE。用 J2EE 進(jìn)行應(yīng)用開發(fā)必須遵守經(jīng)典的 3 層結(jié)構(gòu) —表現(xiàn)層，業(yè)務(wù)層和企業(yè)信息系統(tǒng)層。 業(yè)務(wù)層或者 EJB 層 這一層包含 EJB，即企業(yè)應(yīng)用的事務(wù)邏輯模型。 EJB 對(duì)象允許或者本地 EJB 對(duì)象是特定 EJB 實(shí)例的代理。我們應(yīng)該把注意力放在 版本上，而實(shí)際上是在學(xué)習(xí)后者。 (2) Web 組件（ Servlet、 JSP） 。數(shù)據(jù)源是提供給應(yīng)用服務(wù)器的為事務(wù)組件進(jìn)入到企業(yè)信息服務(wù)層提供數(shù)據(jù)接口，通常由被應(yīng)用服務(wù)器管理的 JDBC 連接池實(shí)例化。 (1) 遠(yuǎn)程 EJB 調(diào)用：同步的 EJB 調(diào)用通過主 EJB 對(duì)象和 EJB 對(duì)象接口來實(shí)現(xiàn)。雖然查詢的協(xié)議還沒有被標(biāo)準(zhǔn)化，但是假設(shè)一個(gè)基于 JMX或者 JNDI 的查詢是合理的。 然而，沒有一個(gè)現(xiàn)代的應(yīng)用服務(wù)器允許詳細(xì)的控制所有組件類型的部署過程除了在它們的部署解釋器中的有限的選擇。 本地交互 一些組件間的交 互可以發(fā)生在同一地點(diǎn)的相同應(yīng)用服務(wù)器虛擬機(jī)的組件間，有時(shí)候甚至可以發(fā)生在只有相同容器的組件間。 為了著手構(gòu)建一個(gè)能夠部署不可網(wǎng)絡(luò)的動(dòng)態(tài)的分布式的架構(gòu)，我們提出了一種普遍的部署單元即一個(gè)簡單的基于 xml 部署的解釋器或者是一組類似的綁定到文檔中的解釋器。與之相似的是，一個(gè)消息驅(qū)動(dòng)的 bean，也隱式需要一種運(yùn)行在網(wǎng)絡(luò)上消息服務(wù)實(shí)例。例如， JBoss 利用 Java 管理擴(kuò)展服務(wù)器來實(shí)現(xiàn)基本的命名和調(diào)用功能。 1 Introduction In recent years, we have seen a significant growth in ponentbased enterprise application development. These applications are typically deployed on pany Intras or on the Inter and are characterized by high transaction volume, large numbers of users and wide area access. Traditionally they are deployed in a central location, using server clustering with load balancing (horizontal partitioning) to sustain user load. However, horizontal partitioning has been shown very efficient only in reducing applicationrelated overheads of userperceived response times, without having much effect on workinduced latencies. Vertical partitioning (., running web tier and business tier in separate VMs) has been used for fault isolation and load balancing but it is sometimes impractical due to significant runtime overheads (even if one would keep the tiers on a fast localarea work) related to heavy use of remote invocations. Recent work [14] in the context of J2EE ponent based applications has shown viability of vertical partitioning in widearea works without incurring the aforementioned overheads. The key conclusions from that study can be summarized as follows: ? Using properly designed applications, vertical distribution across widearea works improves userperceived latencies. ? Widearea vertical layering requires replication of application ponents and maintaining consistency between replicas. ? Additional replicas may be deployed dynamically to handle new requests. ? Different replicas may, in fact, be different implementations of the same ponent based on usage (readonly, readwrite). ? New request paths may reuse ponents from previously deployed paths. Applying intelligent monitoring [6] and AI planning [2, 12] techniques in conjunction with the conclusions of that study, we see a potential for dynamic adaptation in industrystandard J2EE ponentbased applications in wide area works Through deployment of additional application ponents dynamically based on active monitoring. However, in order to achieve such dynamic adaptation, we need an infrastructure for automating J2EE application deployment in such an environment. This need is quite evident to anyone who has ever tried deploying a J2EE application even on a single application server, which is a task that involves a great deal of configuration of both the system services and application ponents. For example one has to set up JDBC data sources, messaging destinations and other resource adapters before application ponents can be configured and deployed. In a wide area deployment that spans multiple server nodes, this proves even more plex, since more system services that facilitate internode munications need to be configured and started and a variety of configuration data, like IP addresses, port numbers, JNDI names and others have to be consistently maintained in various configuration files on multiple nodes. This distributed deployment infrastructure must be able to: ? address interponent connectivity specification and define its effects on ponent configuration and deployment, ? address application ponent dependencies on application server services, their configuration and deployment, ? provide simple but expressive abstractions to control adaptation through dynamic deployment and undeployment of ponents, ? enable reuse of services and ponents to maintain efficient use of work nodes’ resources, ? provide these facilities without incurring significant additional design effort on behalf of application programmers. In this paper we propose the infrastructure for automatic dynamic deployment of J2EE applications, which addresses all of the aforementioned issues. The