?? jb7-1-1.htm
字號(hào):
mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"">開(kāi)發(fā)一個(gè)</span><span lang="EN-US">EJB</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">分布式應(yīng)用程序的最后一步是部署應(yīng)用程序并在其運(yùn)行時(shí)監(jiān)測(cè)企業(yè)級(jí)的計(jì)算和網(wǎng)絡(luò)環(huán)境。以下就是這兩個(gè)部署與運(yùn)行角色：</span></p>
<p class="MsoNormal" style="margin-left:57.0pt;text-indent:-21.0pt;mso-list:l0 level1 lfo1;
tab-stops:list 57.0pt"><span lang="EN-US" style="font-family:
Wingdings">l</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">部署者（</span><span lang="EN-US">Deployer</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">）</span></p>
<p class="MsoNormal" style="margin-left:57.0pt"><span style="font-family:宋體;
mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"">部署者懂得分布式應(yīng)用程序的運(yùn)行環(huán)境。他們利用容器提供者提供的工具來(lái)修改</span><span lang="EN-US">enterprise
beans</span><span style="font-family:宋體;mso-ascii-font-family:
"Times New Roman";mso-hansi-font-family:"Times New Roman"">的屬性以適應(yīng)于目標(biāo)運(yùn)行環(huán)境。列如，部署者通過(guò)設(shè)置部署描述器中適當(dāng)?shù)膶傩詠?lái)調(diào)整事務(wù)和安全特性。他們也將現(xiàn)成的企業(yè)級(jí)的管理軟件集成進(jìn)應(yīng)用程序。</span></p>
<p class="MsoNormal" style="margin-left:57.0pt;text-indent:-21.0pt;mso-list:l0 level1 lfo1;
tab-stops:list 57.0pt"><span lang="EN-US" style="font-family:
Wingdings">l<span style="font:7.0pt "Times New Roman""> </span></span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">系統(tǒng)管理員（</span><span lang="EN-US">System
administrator</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">）</span></p>
<p class="MsoNormal" style="margin-left:57.0pt"><span style="font-family:宋體;
mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"">一旦應(yīng)用程序部署完畢，由系統(tǒng)管理員監(jiān)測(cè)其運(yùn)行情況，并且當(dāng)其運(yùn)行失常時(shí)采取適當(dāng)措施。管理員負(fù)責(zé)為</span><span lang="EN-US">EJB</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">服務(wù)器和容器提供企業(yè)級(jí)的計(jì)算和網(wǎng)絡(luò)環(huán)境的配置和管理。</span><b><span lang="EN-US" style="font-size:12.0pt"> <o:p>
</o:p>
</span></b></p>
<hr>
<p><b><font color="#000080" size="3"><span lang="EN-US">EJB</span><span style="font-size:12.0pt;font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">體系結(jié)構(gòu)</span></font><span lang="EN-US" style="font-size:12.0pt"><font color="#000080"><o:p>
</font>
</o:p>
</span></b></p>
<p class="MsoNormal"><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">多層的分布式應(yīng)用程序通常由運(yùn)行于本地的客戶(hù)機(jī)，包含商業(yè)邏輯的運(yùn)行于服務(wù)器上的中間層和由企業(yè)級(jí)的信息系統(tǒng)（</span><span lang="EN-US">EIS</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">）組成的后端三部分組成。一個(gè)</span><span lang="EN-US">EIS</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">可以是一個(gè)關(guān)系數(shù)據(jù)庫(kù)，一個(gè)</span><span lang="EN-US">ERP</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">系統(tǒng)，一個(gè)傳統(tǒng)應(yīng)用程序或任何需要數(shù)據(jù)訪問(wèn)的數(shù)據(jù)儲(chǔ)存庫(kù)。下圖展示了一個(gè)標(biāo)準(zhǔn)的</span><span lang="EN-US">EJB</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">多層分布式應(yīng)用程序，包含三層：客戶(hù)端；部署容器和</span><span lang="EN-US">beans</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">的服務(wù)器；以及企業(yè)級(jí)的信息系統(tǒng)。</span></p>
<p class="MsoNormal"><span lang="EN-US">EJB</span><span style="font-family:宋體;
mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"">體系結(jié)構(gòu)圖</span></p>
<p class="MsoNormal"><img border="0" src="ejb_architecture.gif" width="675" height="561"></p>
<p class="MsoNormal"><span lang="EN-US"> <o:p>
</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">由于我們感興趣的是怎樣開(kāi)發(fā)</span><span lang="EN-US">enterprise
beans</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">，所以我們把精力集中于中間層。</span></p>
<p class="MsoNormal"><b><span lang="EN-US"><font color="#000080">EJB</font></span><font color="#000080"><span style="font-family:
宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"">服務(wù)器</span></font><span lang="EN-US"><font color="#000080"><o:p>
</font>
</o:p>
</span></b></p>
<p class="MsoNormal"><span lang="EN-US">EJB</span><span style="font-family:宋體;
mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"">服務(wù)器為</span><span lang="EN-US">enterprise
beans</span><span style="font-family:宋體;mso-ascii-font-family:
"Times New Roman";mso-hansi-font-family:"Times New Roman"">和運(yùn)行</span><span lang="EN-US">beans</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">的容器提供系統(tǒng)服務(wù)。它必須具有一個(gè)</span><span lang="EN-US">JIDI</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">（</span><span lang="EN-US" style="mso-bidi-font-size:10.0pt;font-family:Verdana;color:black">Java
</span><span style="mso-bidi-font-size:10.0pt;font-family:宋體;mso-ascii-font-family:Verdana;
mso-hansi-font-family:Verdana;color:black">命名和目錄接口</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">）訪問(wèn)能力的命名服務(wù)和事務(wù)管理。</span><span lang="EN-US">EJB</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">服務(wù)器經(jīng)常會(huì)提供額外的特征以區(qū)別于它的競(jìng)爭(zhēng)者。</span><span lang="EN-US">Borland</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">公司的</span><span lang="EN-US">AppServer</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">就是一個(gè)</span><span lang="EN-US">EJB</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">服務(wù)器的例子。</span></p>
<p class="MsoNormal"><b><span lang="EN-US"><font color="#000080">EJB</font></span><font color="#000080"><span style="font-family:
宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"">容器</span></font></b></p>
<p class="MsoNormal"><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">一個(gè)容器是一個(gè)或多個(gè)</span><span lang="EN-US">enterprise
beans</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">的運(yùn)行時(shí)系統(tǒng)。它提供了</span><span lang="EN-US">beans</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">和</span><span lang="EN-US">EJB</span><span style="font-family:
宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"">服務(wù)器的通信。它提供了事務(wù)、安全和網(wǎng)絡(luò)分布管理。一個(gè)容器既是代碼又是一種為特殊的</span><span lang="EN-US">enterprise
bean</span><span style="font-family:宋體;mso-ascii-font-family:
"Times New Roman";mso-hansi-font-family:"Times New Roman"">生成代碼的工具。一個(gè)容器也提供了一個(gè)</span><span lang="EN-US">enterprise
bean</span><span style="font-family:宋體;mso-ascii-font-family:
"Times New Roman";mso-hansi-font-family:"Times New Roman"">的部署工具，和一種監(jiān)測(cè)和管理應(yīng)用程序的方法。</span><span lang="EN-US">EJB</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">服務(wù)器和</span><span lang="EN-US">EJB</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">容器組合在一起為</span><span lang="EN-US">bean</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">提供了運(yùn)行環(huán)境。容器為一個(gè)或多個(gè)</span><span lang="EN-US">beans</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">提供管理服務(wù)。雖然服務(wù)器為</span><span lang="EN-US">bean</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">提供了各種服務(wù)，但獲取這些服務(wù)是由容器為</span><span lang="EN-US">beans</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">做的。</span></p>
<p class="MsoNormal"><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">雖然容器是</span><span lang="EN-US">Enterprise
JavaBeans</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">體系結(jié)構(gòu)中的關(guān)鍵部分，但</span><span lang="EN-US">enterprise
bean</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">開(kāi)發(fā)者和應(yīng)用組合者不必關(guān)心它，在</span><span lang="EN-US">EJB</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">分布式應(yīng)用程序中它隱于幕后。因本書(shū)不再進(jìn)一步解釋容器及其工作方式。要得到更多的關(guān)于容器的資料，可以參考</span><span lang="EN-US">Enterprise
JavaBeans</span><span style="font-family:宋體;mso-ascii-font-family:
"Times New Roman";mso-hansi-font-family:"Times New Roman"">規(guī)范</span><span lang="EN-US">1.1</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">。要得到更多的關(guān)于</span><span lang="EN-US">Borland
EJB</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">容器的資料，請(qǐng)參閱</span><i><span lang="EN-US">Borland
AppServer's Enterprise JavaBeans </span><span style="font-family:宋體;
mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"">開(kāi)發(fā)指南</span><b><span lang="EN-US"><o:p>
</o:p>
</span></b></i></p>
<p class="MsoNormal"><b><font color="#000080"><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">一個(gè)</span><span lang="EN-US">Enterprise
JavaBeans</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">是如何運(yùn)作的</span></font><span lang="EN-US"><o:p>
</o:p>
</span></b></p>
<p class="MsoNormal"><span lang="EN-US">bean</span><span style="font-family:宋體;
mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"">開(kāi)發(fā)者必須創(chuàng)建以下這些接口和類(lèi)：</span></p>
<p class="MsoNormal" style="margin-left:57.0pt;text-indent:-21.0pt;mso-list:l0 level1 lfo1;
tab-stops:list 57.0pt"><span lang="EN-US" style="font-family:
Wingdings">l<span style="font:7.0pt "Times New Roman"">
</span></span><span lang="EN-US">bean</span><span style="font-family:
宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"">的本地接口（</span><span lang="EN-US">home
interface</span><span style="font-family:宋體;mso-ascii-font-family:
"Times New Roman";mso-hansi-font-family:"Times New Roman"">）</span></p>
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