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<head><title>中间层</title></head>
<center><h1>中间层</h1></center>
<div><P align=right><FONT face=Verdana><FONT color=#f70938><FONT face=黑体><a href="200604112229525.html" tppabs="http://www.itisedu.com/phrase/200604112229525.html" target="_new">中科永联</a>高级技术培训中心（</FONT><FONT face=黑体>www.itisedu.com</FONT><FONT face=黑体>）<IMG src="200632722419623.jpg" tppabs="http://www.itisedu.com/manage/Upload/image/200632722419623.jpg" border=0></FONT></FONT></FONT></P>
<P><FONT face=Verdana> <a href="200603101709095.html" tppabs="http://www.itisedu.com/phrase/200603101709095.html" target="_new">中间层</a> (<a href="javascript:if(confirm('http://www.itisedu.com/phrase/200604241147165.html \n\nThis file was not retrieved by Teleport Pro, because it was unavailable, or its retrieval was aborted, or the project was stopped too soon. \n\nDo you want to open it from the server?'))window.location='http://www.itisedu.com/phrase/200604241147165.html'" tppabs="http://www.itisedu.com/phrase/200604241147165.html" target="_new">Middle Tier</a>)</FONT><FONT face=Verdana>也称作“<a href="javascript:if(confirm('http://www.itisedu.com/phrase/200604241147325.html \n\nThis file was not retrieved by Teleport Pro, because it was unavailable, or its retrieval was aborted, or the project was stopped too soon. \n\nDo you want to open it from the server?'))window.location='http://www.itisedu.com/phrase/200604241147325.html'" tppabs="http://www.itisedu.com/phrase/200604241147325.html" target="_new">应用程序服务器层</a>或<FONT face=Verdana><a href="javascript:if(confirm('http://www.itisedu.com/phrase/200604241147525.html \n\nThis file was not retrieved by Teleport Pro, because it was unavailable, or its retrieval was aborted, or the project was stopped too soon. \n\nDo you want to open it from the server?'))window.location='http://www.itisedu.com/phrase/200604241147525.html'" tppabs="http://www.itisedu.com/phrase/200604241147525.html" target="_new">应用服务层</a></FONT>”，是用户接口或 Web <a href="javascript:if(confirm('http://www.itisedu.com/phrase/200603082208195.html \n\nThis file was not retrieved by Teleport Pro, because it was unavailable, or its retrieval was aborted, or the project was stopped too soon. \n\nDo you want to open it from the server?'))window.location='http://www.itisedu.com/phrase/200603082208195.html'" tppabs="http://www.itisedu.com/phrase/200603082208195.html" target="_new">客户端</a>与<a href="200602271218062.html" tppabs="http://www.itisedu.com/phrase/200602271218062.html" target="_new">数据库</a>之间的逻辑层。典型情况下 Web 服务器位于该层，<a href="javascript:if(confirm('http://www.itisedu.com/phrase/200603091835065.html \n\nThis file was not retrieved by Teleport Pro, because it was unavailable, or its retrieval was aborted, or the project was stopped too soon. \n\nDo you want to open it from the server?'))window.location='http://www.itisedu.com/phrase/200603091835065.html'" tppabs="http://www.itisedu.com/phrase/200603091835065.html" target="_new">业务对象</a>在此实例化。中间层是生成并操作接收信息的业务规则和函数的集合。它们通过业务规则（可以频繁更改）完成该任务，并由此被封装到在物理上与应用<a href="200604232224305.html" tppabs="http://www.itisedu.com/phrase/200604232224305.html" target="_new">程序</a>程序逻辑本身相独立的<a href="200603302222545.html" tppabs="http://www.itisedu.com/phrase/200603302222545.html" target="_new">组件</a>中。请参见<a href="javascript:if(confirm('http://www.itisedu.com/phrase/200603101712585.html \n\nThis file was not retrieved by Teleport Pro, because it was unavailable, or its retrieval was aborted, or the project was stopped too soon. \n\nDo you want to open it from the server?'))window.location='http://www.itisedu.com/phrase/200603101712585.html'" tppabs="http://www.itisedu.com/phrase/200603101712585.html" target="_new">客户端层</a>、<a href="javascript:if(confirm('http://www.itisedu.com/phrase/200603101713485.html \n\nThis file was not retrieved by Teleport Pro, because it was unavailable, or its retrieval was aborted, or the project was stopped too soon. \n\nDo you want to open it from the server?'))window.location='http://www.itisedu.com/phrase/200603101713485.html'" tppabs="http://www.itisedu.com/phrase/200603101713485.html" target="_new">数据源层</a>。</FONT></P>
<P><FONT face=Verdana> 三层网络结构指的是将数据处理过程分为三部分：第一层是客户端(<a href="javascript:if(confirm('http://www.itisedu.com/phrase/200604241148495.html \n\nThis file was not retrieved by Teleport Pro, because it was unavailable, or its retrieval was aborted, or the project was stopped too soon. \n\nDo you want to open it from the server?'))window.location='http://www.itisedu.com/phrase/200604241148495.html'" tppabs="http://www.itisedu.com/phrase/200604241148495.html" target="_new">用户界面层</a>)，提供用户与系统的友好访问；第二层是应用服务层（也叫中间层），专司业务逻辑的实现；第三层是数据源层（<a href="javascript:if(confirm('http://www.itisedu.com/phrase/200604241152135.html \n\nThis file was not retrieved by Teleport Pro, because it was unavailable, or its retrieval was aborted, or the project was stopped too soon. \n\nDo you want to open it from the server?'))window.location='http://www.itisedu.com/phrase/200604241152135.html'" tppabs="http://www.itisedu.com/phrase/200604241152135.html" target="_new">数据服务层</a>，<a href="javascript:if(confirm('http://www.itisedu.com/phrase/200603011056245.html \n\nThis file was not retrieved by Teleport Pro, because it was unavailable, or its retrieval was aborted, or the project was stopped too soon. \n\nDo you want to open it from the server?'))window.location='http://www.itisedu.com/phrase/200603011056245.html'" tppabs="http://www.itisedu.com/phrase/200603011056245.html" target="_new">数据库系统</a>），负责数据信息的存储、访问及其优化。由于业务逻辑被提取到应用服务层，大大降低了客户端负担，因此也成为瘦客户(Thin <a href="javascript:if(confirm('http://www.itisedu.com/phrase/200604231337375.html \n\nThis file was not retrieved by Teleport Pro, because it was unavailable, or its retrieval was aborted, or the project was stopped too soon. \n\nDo you want to open it from the server?'))window.location='http://www.itisedu.com/phrase/200604231337375.html'" tppabs="http://www.itisedu.com/phrase/200604231337375.html" target="_new">Client</a>)结构，三层结构在传统的二层结构的基础上增加了应用服务层，将应用逻辑单独进行处理，从而使得用户界面与应用逻辑位于不同的平台上，两者之间的通信协议由系统自行定义。通过这样的结构设计，使得应用逻辑被所有用户共享，这是两层结构应用<a href="200604232134205.html" tppabs="http://www.itisedu.com/phrase/200604232134205.html" target="_new">软件</a>与三层应用软件之间最大的区别。三层结构将表示部分和业务逻辑部分按照客户层和应用服务层相分离，客户端和应用服务层、应用服务层和数据库服务层之间的通讯、异构平台之间的数据交换等都可以通过<a href="200604241155005.html" tppabs="http://www.itisedu.com/phrase/200604241155005.html" target="_new">中间件</a>或者相关程序来实现。当数据库或者应用服务层的业务逻辑改变时，客户端并不需要改变，反之亦然，大大提高了系统模块的复用性，缩短开发周期，降低维护费用。以Java <a href="javascript:if(confirm('http://www.itisedu.com/phrase/200604201518585.html \n\nThis file was not retrieved by Teleport Pro, because it was unavailable, or its retrieval was aborted, or the project was stopped too soon. \n\nDo you want to open it from the server?'))window.location='http://www.itisedu.com/phrase/200604201518585.html'" tppabs="http://www.itisedu.com/phrase/200604201518585.html" target="_new">Applet</a>为客户端， 以Java <a href="javascript:if(confirm('http://www.itisedu.com/phrase/200603091005185.html \n\nThis file was not retrieved by Teleport Pro, because it was unavailable, or its retrieval was aborted, or the project was stopped too soon. \n\nDo you want to open it from the server?'))window.location='http://www.itisedu.com/phrase/200603091005185.html'" tppabs="http://www.itisedu.com/phrase/200603091005185.html" target="_new">Servlet</a>为中间层的三层网络结构，在目前的实时网络信息平台得到了广泛的应用，其结构和一般的三层结构如图1所示：</FONT></P>
<P align=center><IMG src="200644134153280.gif" tppabs="http://www.itisedu.com/manage/Upload/image/200644134153280.gif" border=0></P>
<P><FONT face=Verdana><STRONG>中间层驱动工作原理</STRONG></FONT></P>
<P><FONT face=Verdana>（1）注册表常识：<BR> 1）、设备数据库所在的注册表健值为：<BR> HKLM\SYSTEM\CurrentControlSet\Enum\<BR> ENUM子项中是一个设备数据库，在数据库存放<a href="200603021438435.html" tppabs="http://www.itisedu.com/phrase/200603021438435.html" target="_new">计算机</a>中所有安装的，并且被系统认识到的设备。<BR> 所有的用户（包括管理员）都不能更改ENUM项的内容。这是为了保护<a href="200602281634075.html" tppabs="http://www.itisedu.com/phrase/200602281634075.html" target="_new">操作系统</a>和安装的设备的完整性。为了更改设备的设置，应该使用"设备管理器"。<BR> 为了在设备管理器中现实隐藏的，非即插即用的，以及没有连接到计算机上的所有设备，你应该首先在命令解释器中敲入命令set DEVMGR_SHOW_NONPRESENT_DEVICES=1，然后启动设备管理器，就可以在设备管理器中删除和重新配置这些设备了。</FONT></P>
<P><FONT face=Verdana> 2）、硬件设备<a href="200603090857555.html" tppabs="http://www.itisedu.com/phrase/200603090857555.html" target="_new">类</a>所在的注册表健值为：<BR> HKLM\SYSTEM\CurrentControlSet\Control\<a href="javascript:if(confirm('http://www.itisedu.com/phrase/200604231359565.html \n\nThis file was not retrieved by Teleport Pro, because it was unavailable, or its retrieval was aborted, or the project was stopped too soon. \n\nDo you want to open it from the server?'))window.location='http://www.itisedu.com/phrase/200604231359565.html'" tppabs="http://www.itisedu.com/phrase/200604231359565.html" target="_new">Class</a>\<BR> Class项下存放硬件设备类的配置信息。在Class项下的每个子项都代表一个设备类，子项的名称使用"唯一全局标识符（GUIS）"，这些标识符存放该设备类的配置信息。在每个类标识符下，还会有以4位数命名的子项，他们代表该设备类里的具体设备，其他的配置数据只应用于该具体设备。<BR> 如网卡的设备类是{4D36E972-E325-11CE-BFC1-08002BE10318}，并假定我们网卡对应的4为数命名子项名为0005。<BR> 其中<BR>HKLM\SYSTEM\CurrentControlSet\Class\{4D36E972-E325-11CE-BFC1-08002BE10318}\0005\Linkage\ 中：<BR>Export：代表该设备在设备名字空间输出的设备名字。<BR>RootDevice：代表当前设备的GUID。中间层驱动这里有两个GUID，第一个是自己的GUID，第二个是该中间层驱动绑定的下层MINIPORT的GUID。<BR>UpperBind：代表上层绑定它的NDIS协议驱动或NDIS中间层驱动。当某个协议驱动绑定该MINIPORT设备时，则这个协议驱动的名字必须出现在UpperBind健值的字符串中，否则不能进行绑定。也就是说，UpperBind健值的字符串决定了那个协议驱动（当然也包括中间层驱动注册的协议）和当前的MINIPORT设备绑定，即，它决定了NDIS的上下层绑定关系。</FONT></P>
<P><FONT face=Verdana>注：一般添加中间层驱动后，中间层驱动只插入到真是网卡和相应协议中间，不会插入到虚拟网卡（如安装虚拟机后虚拟出来的网卡设备）和相应协议中间。</FONT></P>
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