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📁 详细介绍了jboss3.0的配置等
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   <title>ContainerInvoker - Container entry point</title><link rel="stylesheet" href="styles.css" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/styles.css" type="text/css"><meta name="generator" content="DocBook XSL Stylesheets Vimages/callouts/"><link rel="home" href="index.html" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/index.html" title="JBoss 3.0 Documentation"><link rel="up" href="ch12.html" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/ch12.html" title="Chapter 12. Container architecture - design notes"><link rel="previous" href="ch12s17.html" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/ch12s17.html" title="JMX - foundation of JBoss infrastructure"><link rel="next" href="ch12s31.html" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/ch12s31.html" title="Container"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><table border="0" cellpadding="0" cellspacing="0" height="65"><tr height="65"><td rowspan="2"><img src="jboss.gif" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/jboss.gif" border="0"></td><td rowspan="2" background="gbar.gif" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/gbar.gif" width="100%" align="right" valign="top"><a href="index.html" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/index.html"><img src="doc.gif" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/doc.gif" border="0"></a><a href="ch12.html" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/ch12.html"><img src="toc.gif" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/toc.gif" border="0"></a><a href="ch12s17.html" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/ch12s17.html"><img src="prev.gif" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/prev.gif" border="0"></a><a href="ch12s31.html" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/ch12s31.html"><img src="next.gif" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/next.gif" border="0"></a></td></tr><tr></tr></table><div class="section"><a name="d0e8074"></a><div class="titlepage"><div><h2 class="title" style="clear: both"><a name="d0e8074"></a>ContainerInvoker - Container entry point</h2></div></div><div class="section"><a name="d0e8077"></a><div class="titlepage"><div><h3 class="title"><a name="d0e8077"></a>Introduction</h3></div></div><p>Certainly one of the most important parts of a distributed system
   is its RPC interface, as well as techniques used in passing that RPC
   call between different parts of the system.</p><p>The component that plays the role of the container entry point, a 
"call
   router", to insides of the container is the<tt>ContainerInvoker</tt>. By closely
   looking at this entry point to the JBoss container, one would understand
   the semantics of calls made from clients, client object structure, the
passing
   of client calls over the network layer (a.k.a "wire") and unpacking
   them in a local VM.  Similar semantics are employed in returning the result
   of the call and how it is handled on the client side.  Also, great attention
   has to be dedicated to methods employed in bypassing the network layer if
these
   calls are made from clients local to the container, i.e intra-VM.</p></div><div class="section"><a name="d0e8087"></a><div class="titlepage"><div><h3 class="title"><a name="d0e8087"></a>ContainerInvoker in focus</h3></div></div><div class="section"><a name="d0e8090"></a><div class="titlepage"><div><h4 class="title"><a name="d0e8090"></a>How are calls passed into a container?</h4></div></div><p>Container invoker utilizes RMI exporting* to make itself
    available to remote clients. By implementing<tt>ContainerRemote</tt> interface,
    which in turn extends the familiar <tt>java.rmi.Remote</tt>interface,
    ContainerInvoker acts as an RMI server object and as such is able to
    accept calls that come from both remote clients (other JVMs) and
    from other beans "living" in containers of the same EJB
    application (within the same JVM).</p></div><div class="section"><a name="d0e8101"></a><div class="titlepage"><div><h4 class="title"><a name="d0e8101"></a>ContainerRemote interface - two flavours of invoke methods</h4></div></div><p>Before going further into the details, let's look closer into
    <tt>ContainerRemote</tt> interface.  It has two methods,
    <tt>invoke</tt> and <tt>invokeHome</tt>, each of 
which
    has two flavors:</p><p>
					<pre class="programlisting">public MarshalledObject invoke(MarshalledObject mi)
throws Exception;</pre>
				</p><p>
					<pre class="programlisting">public Object invoke(Object id, Method m, Object[] args,
                               Transaction tx,
                               Principal identity,
                               Object credential )
      throws Exception;</pre>
				</p><p>The first accepts only one parameter
(<tt>MarshalledObject</tt>), while
    second accepts "regular" java objects. Why is this distinction
    between the two sets important? </p><p>The distinction exists exactly for the reason that it enables the
    container to accept both remote and local client calls.  But it is
important
    to notice that not only does this design approach enable two different
    call methodologies, it optimizes them at the same time.</p></div><div class="section"><a name="d0e8132"></a><div class="titlepage"><div><h4 class="title"><a name="d0e8132"></a>Remote call unpacking stage</h4></div></div><p>Remote calls are unpacked from<tt>MarshalledObject</tt>.<tt>MarshalledObject</tt>   contains a byte stream with serialized representation
   of an object given to its constructor. In our case, this object is
   <tt>RemoteMethodInvocation</tt>.
The <tt>RemoteMethodInvocation</tt> instance,
   created by a remote client proxy, describes all needed attributes
   of an EJB method call. Some of these attributes, as you
   may have guessed by now, are the ID of the object, a method to
   invoke, security credentials, principal of the caller(identity),
   and a transactional context of the call.</p></div><div class="section"><a name="d0e8149"></a><div class="titlepage"><div><h4 class="title"><a name="d0e8149"></a>MethodInvocation</h4></div></div><p>Upon receving <tt>MarshalledOjbect</tt> from client
proxy, <tt>ContainerInvoker</tt>   recreates a copy of the original<tt>RemoteMethodInvocation</tt>   object, by deserializing it from the contained byte stream in
   <tt>MarshalledObject</tt>.<tt>RemoteMethoInvocation</tt> is then converted to
   <tt>MethodInvocation</tt> and handed off to the
container.</p></div><div class="section"><a name="d0e8172"></a><div class="titlepage"><div><h4 class="title"><a name="d0e8172"></a>Bean to Bean calls</h4></div></div><p>Local calls coming from clients in the same VM, usually a
   "bean/bean" method call, are directly handed off to the container.
   This bypasses the network layer, and serialization/deserialization
   stage of the call that remote method calls have to go through.</p></div><div class="section"><a name="d0e8177"></a><div class="titlepage"><div><h4 class="title"><a name="d0e8177"></a>Other ContainerInvoker duties</h4></div></div><p>Before forwarding a call to the container,<tt>ContainerInvoker</tt> also
   resets the call's thread classloader with the specified container
   classloader, propagates transaction, and security context. </p><p>Another important role played by<tt>ContainerInvoker</tt> is that it
   provides implementation of <tt>EJBObject</tt> and<tt>EJBHome</tt> parts of container.
   As mentioned before, <tt>ContainerInvoker</tt> creates<tt>EJBObject</tt> and <tt>EJBHome</tt>   in the form of dynamic proxies.</p><p>For example, an <tt>EntityBean</tt> finder may result
in a set of primary
   keys whose EJB-objects should be returned to the client. The
   <tt>ContainerInvoker</tt> is then responsible for creating<tt>EJBObject</tt>   instances that can be used by the client, as specified in the
   EJB 1.1 specification. The client must then be able to remotely
   access the container and actual bean instances through
   these <tt>EJBObjects</tt>.</p></div><div class="section"><a name="d0e8219"></a><div class="titlepage"><div><h4 class="title"><a name="d0e8219"></a>Why ContainerInvoker if we have container?</h4></div></div><p>One may wonder why there is such a big distinction between
   container invoker and the container.<tt>ContainerInvoker</tt> also
   uses the naming tree. Why should the container invoker know
   anything about the naming tree?  You end up having the container
   invoker taking care of all the important registrations...</p><p>Wasn't the container responsible for all this crucial work?</p><p>No, this architectural approach was intentional in JBoss. Since
   different distribution protocols use different naming systems
   (IIOP would use the CORBA naming system), the only part of the
   container that knows what naming system to use is the container invoker.
   Now, if we want to add another/different distribution protocol to JBoss, we
can
   simply implement it in the container invoker; everything else stays
untouched.
   ContainerInvoker is free to choose which distribution protocol to use
   to access the container. Valid options would be JRMP, IIOP, or SOAP. The
default
   plugin uses the standard RMI protocol JRMP to allow client access to
   the container. </p><p>*Exporting - making object available to accept incoming calls by
   listening on specified TCP port</p></div></div></div><table border="0" cellpadding="0" cellspacing="0" height="65"><tr height="65"><td rowspan="2"><img src="gbar.gif" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/gbar.gif" width="432" height="79"></td><td rowspan="2" background="gbar.gif" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/gbar.gif" width="100%" align="right" valign="top"><a href="index.html" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/index.html"><img src="doc.gif" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/doc.gif" border="0"></a><a href="ch12.html" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/ch12.html"><img src="toc.gif" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/toc.gif" border="0"></a><a href="ch12s17.html" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/ch12s17.html"><img src="prev.gif" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/prev.gif" border="0"></a><a href="ch12s31.html" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/ch12s31.html"><img src="next.gif" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/next.gif" border="0"></a></td></tr><tr></tr></table></body></html>

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