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From cha...@apache.org
Subject svn commit: r396498 [1/2] - in /webservices/axis2/trunk/java/xdocs/latest: Axis2ArchitectureGuide.html ServiceArchiveToolReference.html migration.html
Date Mon, 24 Apr 2006 10:03:36 GMT
Author: chatra
Date: Mon Apr 24 03:03:34 2006
New Revision: 396498

URL: http://svn.apache.org/viewcvs?rev=396498&view=rev
Log:
improving documents

Modified:
    webservices/axis2/trunk/java/xdocs/latest/Axis2ArchitectureGuide.html
    webservices/axis2/trunk/java/xdocs/latest/ServiceArchiveToolReference.html
    webservices/axis2/trunk/java/xdocs/latest/migration.html

Modified: webservices/axis2/trunk/java/xdocs/latest/Axis2ArchitectureGuide.html
URL: http://svn.apache.org/viewcvs/webservices/axis2/trunk/java/xdocs/latest/Axis2ArchitectureGuide.html?rev=396498&r1=396497&r2=396498&view=diff
==============================================================================
--- webservices/axis2/trunk/java/xdocs/latest/Axis2ArchitectureGuide.html (original)
+++ webservices/axis2/trunk/java/xdocs/latest/Axis2ArchitectureGuide.html Mon Apr 24 03:03:34 2006
@@ -1,710 +1,717 @@
-<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
-<html>
-<head>
-  <meta http-equiv="content-type" content="text/html; charset=windows-1252">
-  <title>Axis2 Architecture Guide</title>
-  <meta content="20050916;22455288">
-  <meta name="CHANGEDBY" content="Chamikara Jayalath">
-  <meta name="CHANGED" content="20050918;22493797">
-</head>
-
-<body lang="en-US" dir="ltr">
-<h1 align="center">Axis2 Architecture Guide</h1>
-
-<p><i>Version 1.0</i></p>
-<i>Feedback: <a
-href="mailto:axis-dev@ws.apache.org">axis-dev@ws.apache.org</a></i>
-
-<h2>Contents</h2>
-<ul>
-  <li><a href="#bmBP">The Big Picture</a></li>
-  <li><p><a href="#requirements">Requirement of Axis2</a></p>
-  </li>
-  <li><a href="#thearchi">Axis2, The Architecture</a>
-    <ul>
-      <li><p><a href="#bmInfoMod">Information Model</a></p>
-      </li>
-      <li><a href="#bmXML">XML Processing Model</a></li>
-      <li><p><a href="#bmSOAPPM">SOAP Processing Model</a></p>
-        <ul>
-          <li><a href="#default">Axis2 Default Processing Model</a></li>
-          <li><p><a href="#incomingsoap">Processing an Incoming SOAP
-            Message</a></p>
-          </li>
-          <li><a></a><a href="#outgoing">Processing of the Outgoing
-            Message</a></li>
-          <li><p><a href="#extending">Extending SOAP Processing Model</a></p>
-            <ul>
-              <li><a href="#extendingwithhandlers">Extending the SOAP
-                Processing Model with Handlers</a></li>
-              <li><p><a href="#extendingwithmodules">Extending the SOAP
-                Processing Model with Modules</a></p>
-              </li>
-            </ul>
-          </li>
-        </ul>
-      </li>
-      <li><a href="#bmDeployment">Deployment</a>
-        <ul>
-          <li><a href="#xmlfile">The <em>axis2.xml</em> file</a></li>
-          <li><p><a href="#servicearchive">Service Archive</a></p>
-          </li>
-          <li><a href="#modulearchive">Module Archive</a></li>
-        </ul>
-      </li>
-      <li><p><a href="#bmClientAPI">Client API</a></p>
-        <ul>
-          <li><a href="#oneway">One Way Messaging Support</a></li>
-          <li><p><a href="#requestresponse">Request Response Messaging
-            Support</a></p>
-          </li>
-        </ul>
-      </li>
-      <li><a href="#bmTransports">Transports</a></li>
-      <li><p><a href="#bmWSDL">Code generation</a></p>
-      </li>
-      <li><a href="#bmDB">Data Binding</a>
-        <ul>
-          <li><a href="#integration">Integration with the code generation
-            engine</a></li>
-          <li><p><a href="#serial">Serialization and De-Serialization</a></p>
-          </li>
-        </ul>
-      </li>
-    </ul>
-  </li>
-</ul>
-
-<h2><a name="bmBP">The Big Picture</a></h2>
-
-<p>Any architecture is a result of what that architecture should yield. The
-success of an architecture should be evaluated based on the requirements
-expected to be met by that architecture. Let us start our journey into Axis2
-by looking at the requirements.</p>
-<a name="requirements"></a>
-
-<h2>Requirement of Axis2</h2>
-
-<p>In the SOAP terminology, a participant who is taking part in a Web Service
-interaction is known as a SOAP Node. Delivery of a single SOAP Message is
-defined based on two participants, SOAP Sender and SOAP Receiver. Each SOAP
-Message is sent by SOAP Sender and received by SOAP Receiver. A single SOAP
-delivery is the most basic unit that builds the Web Service interaction.</p>
-
-<p>Each SOAP Node may be written in specific programming language, may it be
-Java, C++, .NET or Perl, the Web Services allow them to inter operate. This
-is possible because on the wire each Web Service interaction is done via
-SOAP, which is common to every SOAP Node.</p>
-
-<p><img alt="" src="images/archi-guide/soap.gif" name="Graphic1"
-align="bottom" width="691" height="319" border="0"></p>
-
-<p>Web Service middleware handles the complexity in SOAP messaging and lets
-the users work with the programming language they are accustomed to. Axis2
-allows java users to invoke Web Services using java representations, and
-handles the SOAP messaging behind the curtain.</p>
-
-<p>Axis2 handles SOAP processing along with numerous other tasks. This makes
-the life of the Web Service developer a whole lot easier. Following are the
-identified requirements:</p>
-<ol>
-  <li>Provide a framework to process the SOAP messages. The framework should
-    be extensible and the users should be able to extend the SOAP processing
-    per service or per operation basis. Furthermore it should be able to
-    model different Message Exchange Patterns (MEPs) using the processing
-    framework.</li>
-  <li><p>Ability to deploy a Web Services (with or without WSDL)</p>
-  </li>
-  <li>Provide a Client API that can be used to invoke Web Services. This API
-    should support both the Synchronous and Asynchronous programming
-  models.</li>
-  <li><p>Ability to configure Axis2 and it's components via deployment.</p>
-  </li>
-  <li>Ability to send and receive SOAP messages with different
-  transports.</li>
-</ol>
-
-<p>Apart from the above functionalities, performance in terms of memory and
-speed is a major consideration for Axis2. Axis2 Core Architecture is built on
-three specifications- WSDL, SOAP and WS-Addressing. Other specifications like
-JAX-RP, SAAJ &amp; WS-Policy are layered on top of the Core Architecture.</p>
-
-<h2><a name="thearchi">Axis2, The Architecture</a></h2>
-Axis2 architecture lays out some principals to preserve the uniformity. They
-are as follows:
-<ul>
-  <li><p>Axis2 architecture separates the logic and the states. Code that
-    does the processing is stateless inside Axis2. This allows code to be
-    executed freely by parallel threads.</p>
-  </li>
-  <li>All the information is kept in one information model allowing system to
-    be suspended and resumed.</li>
-</ul>
-
-<p>Axis2 architecture is modular. Therefore Axis2 Framework is built up of
-core modules which collectively make up the core architecture of Axis2, and
-non-core modules that are layered on top of this core
-modules/architecture.</p>
-
-<p>Core Modules:</p>
-<ul>
-  <li><a href="#bmInfoMod">Information Model</a>- Axis2 defines a model to
-    handle information and all states are kept in this model. The model has a
-    hierarchy for the information. The system manages the life cycle of the
-    objects in this hierarchy.</li>
-  <li><p><a href="#bmXML">XML processing Model</a>- Handling the SOAP Message
-    is the most important and most complex task. The efficiency of this is
-    the single most important factor that decides the performance. It makes
-    sense to delegate this task to a separate module allowing that
-    module(AXIOM) to provide a simple API for SOAP and XML info-set while
-    hiding the complexities of the efficient XML processing within the
-    implementation.</p>
-  </li>
-  <li><a href="#bmSOAPPM">SOAP Processing Model</a>- This controls the
-    execution of the processing. The model defines different phases the
-    execution would walk through, and the user can extend the Processing
-    Model at some specific places.</li>
-  <li><p><a href="#bmDeployment">Deployment Model</a>- Axis2 deployment model
-    allows the user to deploy services, configure the transports, extend the
-    SOAP Processing model per system, service or operation basis.</p>
-  </li>
-  <li><a href="#bmClientAPI">Client API</a>- This provides a convenient API
-    for users to communicate with web services using Axis2. There are set of
-    classes to interact with IN-OUT and IN-Only style Message Exchange
-    Patterns (MEPs) where those can be used to construct any other MEP.</li>
-  <li><p><a href="#bmTransports">Transports</a>- Axis2 define a transport
-    framework that enables the user to use different transports. The
-    transports fit into specific places in the SOAP processing model. The
-    implementation provides a few common transports and the user may write
-    new ones if and when it is needed.</p>
-  </li>
-</ul>
-Non-core Modules:
-<ul>
-  <li><a href="#bmWSDL">Code Generation</a>- Axis2 provides a code generation
-    tool that will generate server side and client side code along with a
-    test case. The generated code would simplify the service deployment and
-    the service invocation. This would increase usability of Axis2.</li>
-  <li><p><a href="#bmDB">Data Binding</a>- The basic client API of Axis2 lets
-    the users process SOAP at the infoset level where as data binding extends
-    it to make it more convenient to the users by encapsulating the infoset
-    layer and providing a programming language specific interface.</p>
-  </li>
-</ul>
-<map name="Graphic2Map" id="g2m">
-  <area shape="rect" coords="123,31,222,97" href="#bmInfoMod" alt="">
-  <area shape="rect" coords="239,62,319,134" href="#bmXML" alt="">
-  <area shape="rect" coords="127,112,218,177" href="#bmSOAPPM" alt="">
-  <area shape="rect" coords="12,39,89,95" href="#bmDeployment" alt="">
-  <area shape="rect" coords="0,108,94,156" href="#bmWSDL" alt="">
-  <area shape="rect" coords="350,31,426,86" href="#bmClientAPI" alt="">
-  <area shape="rect" coords="350,114,421,164" href="#bmTransports" alt="">
-</map>
-
-<p><img src="images/archi-guide/all.png" name="Graphic2" width="426" alt=""
-height="189" border="0" align="bottom" usemap="#Graphic2Map"></p>
-
-<h2><a name="bmInfoMod">Information Model</a></h2>
-
-<p>Information Model has two main hierarchies-Contexts and Descriptions. This
-model is described in UML notations below.</p>
-
-<p><img src="images/archi-guide/contexts.png" name="Graphic3" align="bottom"
-alt="" width="400" height="443" border="0"></p>
-
-<p>( A ----&lt;&gt; B says, B has 1 or more objects of A. A------&gt;B says,
-the given relationship holds between A and B.)</p>
-
-<p>The two hierarchies are connected as shown in the above figure. The
-Description hierarchy represents the static data. This data may be loaded
-from a configuration file that exists throughout the lifetime of Axis2. For
-example, deployed Web Services, operations, etc. On the other hand, the
-context hierarchy holds more dynamic information about the things that have
-more than one instances (e.g.Message Context).</p>
-
-<p>These two hierarchies creates a model that provides the ability to search
-for key value pairs. When the values are searched at a given level, they are
-searched while moving up the hierarchy until a match is found. In the
-resulting model the lower levels override the values in the upper levels. For
-example, when a value is looked up in the Message Context and is not found,
-it would be looked up in the Operation Context etc, up the hierarchy. The
-Search is first done up the hierarchy, and if starting point is a Context
-then it is search in the Description hierarchy as well.</p>
-
-<p>This allows the user to declare and override values. Result being a very
-flexible configuration model. The flexibility could be the <em>Achilles</em>
-heel for the system as the search is expensive, specially for something that
-does not exist. Yet in the final analysis developers believe that the
-flexibility would serve better in this instant.</p>
-
-<table width="955" border="1" cellpadding="2" cellspacing="3">
-  <col width="112"><col width="371"><col width="103"><col width="336"><tbody>
-   <tr>
-      <td><strong>Context</strong></td>
-      <td><strong>Description</strong></td>
-      <td><strong>Configuration</strong></td>
-      <td><strong>Description</strong></td>
-   </tr> 
-   <tr>
-      <td width="112"><p>Configuration Context</p>
-      </td>
-      <td width="371"><p>Holds the run time status. A deep copy of this would
-        essentially make a copy of Axis2.</p>
-      </td>
-      <td width="103"><p>Axis Configuration</p>
-      </td>
-      <td width="336"><p>Holds all global configurations. Transports, global
-        modules, parameters and Services etc.</p>
-      </td>
-    </tr>
-    <tr>
-      <td width="112"><p>Service Group Context</p>
-      </td>
-      <td width="371"><p>Holds information about a particular usage of the
-        respective service group. The life of a Service Group Context starts
-        when a user starts interacting with a service that belong to this
-        service group. This can be used to share information between services
-        (within the same service group) in a single interaction.</p>
-      </td>
-      <td width="103"><p>AxisServiceGroup</p>
-      </td>
-      <td width="336"><p>Holds deployment time information about a particular
-        service group.</p>
-      </td>
-    </tr>
-    <tr>
-      <td width="112"><p>Service Context</p>
-      </td>
-      <td width="371"><p>This context is available throughout the usage of
-        the respective service. This can be used to share information between
-        several MEPs of the same service, within a single interaction.</p>
-      </td>
-      <td width="103"><p>AxisService</p>
-      </td>
-      <td width="336"><p>Hold the Operations and the service level
-        configurations</p>
-      </td>
-    </tr>
-    <tr>
-      <td width="112"><p>Operation Context</p>
-      </td>
-      <td width="371"><p>Holds the information about the current MEP
-        instance, maintain the Messages in the current MEP etc.</p>
-      </td>
-      <td width="103"><p>AxisOperation</p>
-      </td>
-      <td width="336"><p>Holds the operation level configurations</p>
-      </td>
-    </tr>
-    <tr>
-      <td width="112"><a name="messageContext"></a>
-
-        <p>Message Context</p>
-      </td>
-      <td width="371"><p>Holds all the information about the Message
-        currently being executed.</p>
-      </td>
-      <td width="103"><p>AxisMessage</p>
-      </td>
-      <td width="336"><p>Do not hold any information as yet, but can be used
-        as a future extension point.</p>
-      </td>
-    </tr>
-  </tbody>
-</table>
-<a name="bmXML"></a>
-
-<h2>XML Processing Model</h2>
-
-<p>Please refer to the <a href="OMTutorial.html">OM Tutorial</a></p>
-
-<h2><a name="bmSOAPPM">SOAP Processing Model</a></h2>
-
-<p><img src="images/archi-guide/soap-processing.gif" name="Graphic4" alt=""
-align="bottom" width="755" height="348" border="0"></p>
-
-<p>The architecture identified two basic actions a SOAP processor should
-perform, sending and receiving SOAP messages. The architecture provides two
-Pipes ('Flows'), to perform these two basic actions. Axis Engine or the
-driver of Axis2 defines two methods send() and receive() to implement these
-two Pipes. The two pipes are named <i>In Pipe</i> and <i>Out Pipe</i>, and
-the complex Message Exchange Patterns (MEPs) are constructed by combining
-these two pipes.</p>
-
-<p>Extensibility of the SOAP processing model is provided through handlers.
-When a SOAP message is being processed the handlers that are registered would
-be executed. The handlers can be registered in global, service, or operation
-scopes and the final handler chain is calculated combining the handlers from
-all the scopes.</p>
-
-<p>The handlers act as interceptors and they process parts of the SOAP
-message and provide add-on services. Usually handlers work on the SOAP
-headers yet they may access or change the SOAP Body as well.</p>
-
-<p>When a SOAP message is being sent through the Client API, an <i>Out
-Pipe</i> would begin, the <i>Out Pipe</i> invokes the handlers and end with a
-Transport Sender that sends the SOAP message to the target endpoint. The SOAP
-message is received by a Transport Receiver at the target endpoint, which
-reads the SOAP message and starts the <i>In Pipe</i>. The <em>In Pipe</em>
-consists of handlers and ends with the <a href="#mr">Message Receiver</a>,
-which consumes the SOAP message.</p>
-
-<p>Above explained processing happens for each and every SOAP message
-exchanged. After processing one message Axis2 may decide to create other SOAP
-messages, in which case more complex message patterns emerge. However Axis2
-always view the SOAP message in terms of processing a single message. The
-combination of the messages are layered on top of that basic framework.</p>
-
-<p>The two pipes does not differentiate between the Server and the Client.
-The SOAP Processing Model handles the complexity and provides two abstract
-pipes to the user. The different areas or the stages of the pipes are given
-names, and according to the Axis2 slang those are named 'phases'. A Handler
-always runs inside a phase, and the phase provides a mechanism to specify the
-ordering of handlers. Both Pipes have built in phases, and both define the
-areas for 'User Phases' which can be defined by the user.</p>
-
-<p>Following figure shows the two pipes with their pre-defined phases &amp;
-user-defined phases. User-defined phases fit in to the User Phases.</p>
-
-<p><img src="images/archi-guide/phases.png" name="Graphic5" align="bottom"
-alt="" width="525" height="226" border="0"></p>
-
-<h3><a name="default">Axis2 Default Processing Model</a></h3>
-
-<p>Axis2 has some inbuilt handlers that run in inbuilt phases and they create
-the default configuration for the Axis2. We will be looking more in to how to
-extend the default processing Model in the next section.</p>
-There are four special handlers defined in Axis2.
-<ol>
-  <li>Dispatchers - Finds the service and the operation the SOAP message is
-    directed to. Dispatchers always run on the <em>In-Pipe</em> and inside
-    the Dispatch phase. The in-built dispatchers dispatch to a particular
-    operation depending on various conditions like WS-Addressing information,
-    URI information, SOAP action information, etc.,</li>
-</ol>
-<ul>
-  <li><a name="mr">Message Receiver - Consume the SOAP Message And hands that
-    over to application , Message receiver is the last handler of the
-    in-pipe</a></li>
-  <li><p>Transport Sender - Send the SOAP message to the SOAP endpoint the
-    message is destined to. Always runs as last handler in the out-pipe</p>
-  </li>
-</ul>
-
-<h3><a name="incomingsoap">Processing an Incoming SOAP Message</a></h3>
-
-<p>Incoming SOAP Message is always received by a Transport Receiver waiting
-for the SOAP Messages. Once the SOAP Message arrives the transport Headers
-are parsed and a</p>
-<a href="#messageContext">Message Context</a> is created for the incoming
-SOAP Message. Then the <i>In Pipe</i> is executed with the Message Context.
-
-<p>Let us see what happens at each phase of the execution. This process may
-happen either in the server or in the Client. </p>
-<ol>
-  <li>Transport Phase - The handlers are in the phase ment to be process
-    transport specific information such as validate incoming message by
-    looking at various transport headers, add data into message context etc..
-  </li>
-  <li>Pre-Dispatch Phase- The main functionality of the handlers are in this
-    phase is to populate message context in order to do the dispatching. As
-    an example processing of addressing headers happen in this phase , so by
-    looking at addressing headers it will find the name of the service and
-    operation.</li>
-  <li>Dispatch Phase - The Dispatchers run in this phase and find the Service
-    if the service is not found already. <br>
-    The post condition of the dispatch phase work as follows; That checks
-    whether the service and operation are found or not. If the service or
-    operation has not been found by this point the execution will halt and
-    send a "service not found error".</li>
-  <li>User Defined Phases - Users are allowed to engage their custom handlers
-    here.</li>
-  <li>Message Validation Phase - Once the user level execution has taken
-    place this phase validates whether SOAP Message Processing has taken
-    place correctly.</li>
-  <li>Message Processing Phase - The Business logic of the SOAP message is
-    executed here. A <a href="#mr">Message Receiver</a> is registered with
-    each Operation. This Message receiver (associated to the particular
-    operation) will executed as the last Handler of this phase.</li>
-</ol>
-
-<p>There may be other handlers in any of these phases. Users may use custom
-handlers to override the mechanics in each of these phases.</p>
-
-<h3><a name="outgoing">Processing of the Outgoing Message</a></h3>
-
-<p><em>Out Pipe</em> is simpler because the service and operation to dispatch
-is known by the time the pipe is executed. The <em>Out Pipe</em> may be
-initiated by the</p>
-<a href="#mr">Message Receiver</a> or the Client API implementation.Phases of
-the <em>Out Pipe</em> are described below:
-<ol>
-  <li>Message Initialize Phase - Fist phase of the <em>Out Pipe</em>. Serves
-    as the placeholder for the custom handlers</li>
-  <li>User Phases - This executes handlers in user defined phases</li>
-  <li>Transports Phase - Execute any transport handlers taken from the
-    associated transport configuration. The last handler would be a transport
-    Sender which would send the SOAP message to the target end point.</li>
-</ol>
-
-<h3><a name="extending">Extending SOAP Processing Model</a></h3>
-
-<p>Above we discussed the default processing model of Axis2. Now lets discuss
-the extension mechanism for the SOAP processing model. After all, the whole
-effort of making this SOAP engine/processing model was focused much on making
-it extendable.</p>
-
-<p>Idea behind introducing step wise processing of the SOAP message in terms
-of handlers &amp; phases is to allow easier modification of the processing
-order. The notion of phases makes it easier to place handlers in between
-other handlers enabling this modification on the default processing behavior.
-SOAP Processing Model can be extended with handler or Modules.</p>
-<a name="extendingwithhandlers"></a>
-
-<h4>Extending the SOAP Processing Model with Handlers</h4>
-The handlers in a module can specify the phase they need to be placed in.
-Furthermore they can specify their location inside a phase by providing phase
-rules. Phase rules will place a handler
-<ol>
-  <li>as the first handler in a phase.</li>
-  <li>or as the last handler in a phase.</li>
-  <li>or before a given handler</li>
-  <li>or after a given handler</li>
-</ol>
-
-<h4><a name="extendingwithmodules">Extending the SOAP Processing Model with
-Modules</a></h4>
-
-<p>Axis2 defines an entity called a 'module' that can introduce handlers and
-web service operations. A Module in terms of Axis2 usually acts as a
-convenient packaging that include a set of handlers and an associated
-descriptor which includes the phase rules. Modules have the concept of being
-'available' and 'engaged'. 'Availability' means the module is present in the
-system, but has not been activated, i.e., the handlers included inside the
-module have not been used in the processing mechanism. When a module is
-'engaged' it becomes active and the handlers get placed in the proper phases.
-The handlers will act in the same way as explained in the previous section.
-Usually a module will be used to implement a WS-* functionality such as
-WS-Addressing.</p>
-
-<p>Apart from the extension mechanism based on the handlers the WS-*
-specifications suggest a requirement for adding new operations. For example,
-once a user add a Reliable Messaging capability to a Service the "Create
-Sequence" operation needs to be available to the service end point. This can
-be implemented by letting the modules define the operations, and once the
-module is engaged to a service, the necessary operations will be added to
-that service.</p>
-
-<p>A service, operations or the system may engage a module. Once the module
-is engaged the handlers and the operations defined in the module are added to
-the entity that engage them.</p>
-
-<p>Modules can not be added while the Axis2 engine is running, but they will
-be available once the system is restarted.</p>
-<a name="bmDeployment"></a>
-
-<h2>Deployment</h2>
-
-<p>The Deployment Model provides a concrete mechanism to configure Axis2.
-This model has three entities that provide the configuration.</p>
-<a name="xmlfile"></a>
-<h3>The axis2.xml file</h3>
-
-<p>This file holds the global configuration for the client and server, and
-provide following information:</p>
-<ol>
-  <li>The global parameters</li>
-  <li>Registered transports in and transport outs</li>
-  <li>User defined phase names</li>
-  <li>Modules that are engaged globally (to all services)</li>
-  <li>Globally defined <a href="#mr">Message Receivers</a></li>
-</ol>
-<a name="servicearchive"></a>
-
-<h3>Service Archive</h3>
-
-<p>Service archive must have a <em>META-INF/services.xml</em> file and may
-contain the dependent classes. The <em>services.xml</em> file has following
-information.</p>
-<ol>
-  <li>Service level parameters</li>
-  <li>Modules that are engaged Service level</li>
-  <li>Service Specific <a href="#mr">Message Receivers</a></li>
-  <li>Operations inside the Service</li>
-</ol>
-
-<h3><a name="modulearchive">Module Archive</a></h3>
-
-<p>Module archive must have a META-INF/module.xml file and dependent classes.
-The <em>module.xml</em> file has Module parameters and the Operations defined
-in the module.</p>
-
-<p>When the system is starting up Axis2 ask the deployment model to create a
-Axis Configuration. Deployment Model first finds the axis2.xml file and build
-the global configuration. Then it checks for the module archives and then for
-the service archives. After which the corresponding services and modules are
-added to the Axis Configuration. System will build Contexts on top of the
-Axis Configurations and then Axis2 is ready to send or receive the SOAP
-Message. Hot deployment is only allowed for the service, in which case a
-thread will check the repository repeatedly, and then add the service
-corresponding to the new found service archives to the repository.</p>
-<a name="bmClientAPI"></a>
-
-<h2>Client API</h2>
-
-<p>There are three parameters that decide the nature of the Web Service
-interaction.</p>
-<ol>
-  <li>Message Exchange Pattern (MEP)</li>
-  <li>The Behavior of the transport, whether it's One-Way or Two-Way</li>
-  <li>Synchronous/ Asynchronous behavior of the Client API</li>
-</ol>
-
-<p>Variations of the three parameters can result in indefinite number of
-scenarios, even though Axis2 is built on a core that support any messaging
-interaction, the developers were compelled to support only two most widely
-used Message Exchange Patterns (MEPs).</p>
-
-<p>Two supported transports are One-Way and the Request-Response scenarios in
-the Client API. The implementation is based on a class called
-<code>ServiceClient</code> and there are extensions for each MEP that Axis2
-Client API supports.</p>
-
-<h3><a name="oneway">One Way Messaging Support</a></h3>
-
-<p>The One-Way support is provided by the <code>fireAndForget</code> which
-provide by <code>ServiceClient</code> that provides a much simpler interface
-for the user. The Axis2 supports HTTP , SMTP and TCP transports. In the case
-of the HTTP transport the return channel is not used and the HTTP 202 OK is
-returned in the return Channel.</p>
-<a name="requestresponse"></a>
-
-<h3>Request Response Messaging Support</h3>
-
-<p>The Request-Response support is provided by the <code>sendReceive()</code>
-method in ServiceClient ,that provides a much simpler interface for the user.
-The Client API has four ways to configure a given Message Exchange</p>
-<ol>
-  <li>Blocking or Non-Blocking nature - this can be decided by using
-    <code>sendReceive()</code> or <code>sendReceiveNonBlocking()</code>
-    methods</li>
-  <li>Sender transport - transport used to send the SOAP Message</li>
-  <li>Listener transport - transport the Response is received</li>
-  <li>Use Separate Channel - determines whether the response is send over a
-    separate transport connection or not. This can be false only when sender
-    and listener transport is same and is a Two-Way transport.</li>
-</ol>
-
-<p>Depending on the values of the above four parameter, Axis2 behave
-differently.</p>
-<a name="bmTransports"></a>
-
-<h2>Transports</h2>
-
-<p>Axis2 has two basic constructs for transports, Transport Senders and
-Transport Receivers . These are accessed via the AxisConfiguration.</p>
-
-<p>The incoming transport is the transport via which the server side receives
-the message and the outgoing transport is decided based on the addressing
-information (wsa:ReplyTo and wsa:FaultTo). If addressing information is not
-available then the out going transport will be the outputstream of the
-incoming transport (if it is two-way transport).</p>
-
-<p>At the client side the user is free to specify the transport to be
-used.</p>
-
-<p>Transport Senders and Transport Receivers contains following
-information.</p>
-<ol>
-  <li>Transport Sender for Out Configuration</li>
-  <li>Transport Listener for In Configuration</li>
-  <li>Parameters of the transport</li>
-</ol>
-
-<p>Each and every transport Out Configuration defines a transport sender.
-Transport sender sends the SOAP Message over depending on its
-configuration.</p>
-
-<p>Transport receiver waits for the SOAP Messages and for each SOAP Message
-that arrives, it uses the <i>In Pipe</i> to process the SOAP Message.</p>
-
-<p>Axis2 Presently support the following transports:</p>
-<ol>
-  <li>HTTP - In HTTP transport the transport listener is a servlet or
-    org.apache.axis2.transport.http.SimpleHTTPServer provided by Axis2. The
-    transport sender uses commons-httpclient to connect and send the SOAP
-    Message.</li>
-  <li>TCP - This is the most simplest transport, but needs the WS -
-    Addressing support to be functional.</li>
-  <li>SMTP - This works off a single email account. Transport receiver is a
-    thread that checks for emails in fixed time intervals.</li>
-</ol>
-<a name="bmWSDL" id="bmWSDL"></a>
-
-<h2>Code generation</h2>
-
-<p>Although the basic objective of the code generation tool has not changed,
-the code generation module of Axis2 has taken a different approach to
-generate code. Primarily the change is in the use of templates, namely XSL
-templates which gives the code generator the flexibility to generate code in
-multiple languages.</p>
-
-<p>The basic approach is to set the code generator to generate an XML and
-parse it with a template to generate the code file. The following figure
-describes how this shows up in the architecture of the tool.</p>
-
-<p><img src="images/archi-guide/CodegenArchitecture.jpg" name="Graphic6"
-alt="" align="bottom" width="478" height="218" border="0"></p>
-
-<p>The fact here is that it is the same information that is extracted from
-the WSDL no matter what code is generated. Code generator uses the WOM (WSDL
-Object Model) internally to manipulate the WSDL and passes that information
-to the emitter which emits an XML. The XML is then parsed with the relevant
-XSL to generate the code. No matter what the language, the process is the
-same except for the template that is being used</p>
-
-<h2><a name="bmDB" id="bmDB">Data Binding</a></h2>
-<a name="integration"></a>
-
-<h3>Integration with the code generation engine</h3>
-
-<p>Axis2 M2 was released with code generation support but without data
-binding. The version 0.9 was shipped with data binding support with complete
-schema support. Such claim is made possible because of the fact that the data
-binding tool, xml-beans, has the full schema support. The original
-architecture of the code generation framework did not undergo significant
-changes because of the way that the code generation framework was originally
-designed. Data binding was incorporated as a pluggable extension to the code
-generation engine. Axis2 version 0.91 does not support SOAP encoding. It only
-supports RPC literal or document literal massages.</p>
-
-<p><img src="images/codegen.gif" name="Graphic7" align="bottom" width="406"
-alt="" height="467" border="0"></p>
-
-<h3><a name="serial">Serialization and De-Serialization</a></h3>
-
-<p>AXIOM is based on a StAX (Streaming API for XML) API. Xml-beans supports
-StAX API. Data binding in Axis2 is achieved through interfacing the AXIOM
-with the Xml-beans using the StAX API which is supported by both parties. At
-the time of the code generation there will be supporter classes for each WSDL
-operation that will have the utility methods that can de-serialize the from
-AXIOM to data bound object and serialize from data bound object to AXIOM. For
-example if the WSDL has an operation called "echoString", once the code is
-generated there will be an echoStringDatabindingSupporter.java class
-generated that will have methods that will look like the following.</p>
-
-<p><code>public static
-org.apache.axiom.om.OMElementtoOM(org.soapinterop.xsd.EchoStringParamDocument
-param)</code><code>// This method will handle the serialization.</code></p>
-
-<p><code>public static org.apache.xmlbeans.XmlObject
-fromOM(org.apache.axis2.om.OMElement param, java.lang.Class type) //This
-method will handle the de-serialization.</code></p>
-
-<p><code>public static org.apache.xmlbeans.XmlObject
-getTestObject(java.lang.Class type) /*This will be a utility method that can
-be used to create sample objects of the given data bound object.*/</code></p>
-
-<p></p>
-</body>
-</html>
+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
+<html>
+<head>
+  <meta http-equiv="content-type" content="text/html; charset=windows-1252">
+  <title>Axis2 Architecture Guide</title>
+  <meta content="20050916;22455288">
+  <meta name="CHANGEDBY" content="Chamikara Jayalath">
+  <meta name="CHANGED" content="20050918;22493797">
+</head>
+
+<body lang="en-US" dir="ltr">
+<h1 align="center">Apache Axis2 Architecture Guide</h1>
+
+<p><i>-Axis2 Version 1.0</i></p>
+
+<p>This document will give an introduction to Axis2's modular architecture
+with explanations on every module.</p>
+
+<p><i>Send your feedback to: <a
+href="mailto:axis-dev@ws.apache.org">axis-dev@ws.apache.org</a></i>. Prefix
+subject with [Axis2]. To subscribe to mailing list see <a
+href="http://ws.apache.org/axis2/mail-lists.html">here.</a></p>
+
+<h2>Contents</h2>
+<ul>
+  <li><a href="#bmBP">The Big Picture</a></li>
+  <li><p><a href="#requirements">Requirement of Axis2</a></p>
+  </li>
+  <li><a href="#thearchi">Axis2, The Architecture</a>
+    <ul>
+      <li><p><a href="#bmInfoMod">Information Model</a></p>
+      </li>
+      <li><a href="#bmXML">XML Processing Model</a></li>
+      <li><p><a href="#bmSOAPPM">SOAP Processing Model</a></p>
+        <ul>
+          <li><a href="#default">Axis2 Default Processing Model</a></li>
+          <li><p><a href="#incomingsoap">Processing an Incoming SOAP
+            Message</a></p>
+          </li>
+          <li><a></a><a href="#outgoing">Processing of the Outgoing
+            Message</a></li>
+          <li><p><a href="#extending">Extending SOAP Processing Model</a></p>
+            <ul>
+              <li><a href="#extendingwithhandlers">Extending the SOAP
+                Processing Model with Handlers</a></li>
+              <li><p><a href="#extendingwithmodules">Extending the SOAP
+                Processing Model with Modules</a></p>
+              </li>
+            </ul>
+          </li>
+        </ul>
+      </li>
+      <li><a href="#bmDeployment">Deployment</a>
+        <ul>
+          <li><a href="#xmlfile">The <em>axis2.xml</em> file</a></li>
+          <li><p><a href="#servicearchive">Service Archive</a></p>
+          </li>
+          <li><a href="#modulearchive">Module Archive</a></li>
+        </ul>
+      </li>
+      <li><p><a href="#bmClientAPI">Client API</a></p>
+        <ul>
+          <li><a href="#oneway">One Way Messaging Support</a></li>
+          <li><p><a href="#requestresponse">Request Response Messaging
+            Support</a></p>
+          </li>
+        </ul>
+      </li>
+      <li><a href="#bmTransports">Transports</a></li>
+      <li><p><a href="#bmWSDL">Code generation</a></p>
+      </li>
+      <li><a href="#bmDB">Data Binding</a>
+        <ul>
+          <li><a href="#integration">Integration with the code generation
+            engine</a></li>
+          <li><p><a href="#serial">Serialization and De-Serialization</a></p>
+          </li>
+        </ul>
+      </li>
+    </ul>
+  </li>
+</ul>
+
+<h2><a name="bmBP">The Big Picture</a></h2>
+
+<p>Any architecture is a result of what that architecture should yield. The
+success of an architecture should be evaluated based on the requirements
+expected to be met by that architecture. Let us start our journey into Axis2
+by looking at the requirements.</p>
+<a name="requirements"></a>
+
+<h2>Requirement of Axis2</h2>
+
+<p>In the SOAP terminology, a participant who is taking part in a Web Service
+interaction is known as a SOAP Node. Delivery of a single SOAP Message is
+defined based on two participants, SOAP Sender and SOAP Receiver. Each SOAP
+Message is sent by SOAP Sender and received by SOAP Receiver. A single SOAP
+delivery is the most basic unit that builds the Web Service interaction.</p>
+
+<p>Each SOAP Node may be written in specific programming language, may it be
+Java, C++, .NET or Perl, the Web Services allow them to inter operate. This
+is possible because on the wire each Web Service interaction is done via
+SOAP, which is common to every SOAP Node.</p>
+
+<p><img alt="" src="images/archi-guide/soap.gif" name="Graphic1"
+align="bottom" width="691" height="319" border="0"></p>
+
+<p>Web Service middleware handles the complexity in SOAP messaging and lets
+the users work with the programming language they are accustomed to. Axis2
+allows java users to invoke Web Services using java representations, and
+handles the SOAP messaging behind the curtain.</p>
+
+<p>Axis2 handles SOAP processing along with numerous other tasks. This makes
+the life of the Web Service developer a whole lot easier. Following are the
+identified requirements:</p>
+<ol>
+  <li>Provide a framework to process the SOAP messages. The framework should
+    be extensible and the users should be able to extend the SOAP processing
+    per service or per operation basis. Furthermore it should be able to
+    model different Message Exchange Patterns (MEPs) using the processing
+    framework.</li>
+  <li><p>Ability to deploy a Web Services (with or without WSDL)</p>
+  </li>
+  <li>Provide a Client API that can be used to invoke Web Services. This API
+    should support both the Synchronous and Asynchronous programming
+  models.</li>
+  <li><p>Ability to configure Axis2 and it's components via deployment.</p>
+  </li>
+  <li>Ability to send and receive SOAP messages with different
+  transports.</li>
+</ol>
+
+<p>Apart from the above functionalities, performance in terms of memory and
+speed is a major consideration for Axis2. Axis2 Core Architecture is built on
+three specifications- WSDL, SOAP and WS-Addressing. Other specifications like
+JAX-RP, SAAJ &amp; WS-Policy are layered on top of the Core Architecture.</p>
+
+<h2><a name="thearchi">Axis2, The Architecture</a></h2>
+Axis2 architecture lays out some principals to preserve the uniformity. They
+are as follows:
+<ul>
+  <li><p>Axis2 architecture separates the logic and the states. Code that
+    does the processing is stateless inside Axis2. This allows code to be
+    executed freely by parallel threads.</p>
+  </li>
+  <li>All the information is kept in one information model allowing system to
+    be suspended and resumed.</li>
+</ul>
+
+<p>Axis2 architecture is modular. Therefore Axis2 Framework is built up of
+core modules which collectively make up the core architecture of Axis2, and
+non-core modules that are layered on top of this core
+modules/architecture.</p>
+
+<p>Core Modules:</p>
+<ul>
+  <li><a href="#bmInfoMod">Information Model</a>- Axis2 defines a model to
+    handle information and all states are kept in this model. The model has a
+    hierarchy for the information. The system manages the life cycle of the
+    objects in this hierarchy.</li>
+  <li><p><a href="#bmXML">XML processing Model</a>- Handling the SOAP Message
+    is the most important and most complex task. The efficiency of this is
+    the single most important factor that decides the performance. It makes
+    sense to delegate this task to a separate module allowing that
+    module(AXIOM) to provide a simple API for SOAP and XML info-set while
+    hiding the complexities of the efficient XML processing within the
+    implementation.</p>
+  </li>
+  <li><a href="#bmSOAPPM">SOAP Processing Model</a>- This controls the
+    execution of the processing. The model defines different phases the
+    execution would walk through, and the user can extend the Processing
+    Model at some specific places.</li>
+  <li><p><a href="#bmDeployment">Deployment Model</a>- Axis2 deployment model
+    allows the user to deploy services, configure the transports, extend the
+    SOAP Processing model per system, service or operation basis.</p>
+  </li>
+  <li><a href="#bmClientAPI">Client API</a>- This provides a convenient API
+    for users to communicate with web services using Axis2. There are set of
+    classes to interact with IN-OUT and IN-Only style Message Exchange
+    Patterns (MEPs) where those can be used to construct any other MEP.</li>
+  <li><p><a href="#bmTransports">Transports</a>- Axis2 define a transport
+    framework that enables the user to use different transports. The
+    transports fit into specific places in the SOAP processing model. The
+    implementation provides a few common transports and the user may write
+    new ones if and when it is needed.</p>
+  </li>
+</ul>
+Non-core Modules:
+<ul>
+  <li><a href="#bmWSDL">Code Generation</a>- Axis2 provides a code generation
+    tool that will generate server side and client side code along with a
+    test case. The generated code would simplify the service deployment and
+    the service invocation. This would increase usability of Axis2.</li>
+  <li><p><a href="#bmDB">Data Binding</a>- The basic client API of Axis2 lets
+    the users process SOAP at the infoset level where as data binding extends
+    it to make it more convenient to the users by encapsulating the infoset
+    layer and providing a programming language specific interface.</p>
+  </li>
+</ul>
+<map name="Graphic2Map" id="g2m">
+  <area shape="rect" coords="123,31,222,97" href="#bmInfoMod" alt="">
+  <area shape="rect" coords="239,62,319,134" href="#bmXML" alt="">
+  <area shape="rect" coords="127,112,218,177" href="#bmSOAPPM" alt="">
+  <area shape="rect" coords="12,39,89,95" href="#bmDeployment" alt="">
+  <area shape="rect" coords="0,108,94,156" href="#bmWSDL" alt="">
+  <area shape="rect" coords="350,31,426,86" href="#bmClientAPI" alt="">
+  <area shape="rect" coords="350,114,421,164" href="#bmTransports" alt="">
+</map>
+
+<p><img src="images/archi-guide/all.png" name="Graphic2" width="426" alt=""
+height="189" border="0" align="bottom" usemap="#Graphic2Map"></p>
+
+<h2><a name="bmInfoMod">Information Model</a></h2>
+
+<p>Information Model has two main hierarchies-Contexts and Descriptions. This
+model is described in UML notations below.</p>
+
+<p><img src="images/archi-guide/contexts.png" name="Graphic3" align="bottom"
+alt="" width="400" height="443" border="0"></p>
+
+<p>( A ----&lt;&gt; B says, B has 1 or more objects of A. A------&gt;B says,
+the given relationship holds between A and B.)</p>
+
+<p>The two hierarchies are connected as shown in the above figure. The
+Description hierarchy represents the static data. This data may be loaded
+from a configuration file that exists throughout the lifetime of Axis2. For
+example, deployed Web Services, operations, etc. On the other hand, the
+context hierarchy holds more dynamic information about the things that have
+more than one instances (e.g.Message Context).</p>
+
+<p>These two hierarchies creates a model that provides the ability to search
+for key value pairs. When the values are searched at a given level, they are
+searched while moving up the hierarchy until a match is found. In the
+resulting model the lower levels override the values in the upper levels. For
+example, when a value is looked up in the Message Context and is not found,
+it would be looked up in the Operation Context etc, up the hierarchy. The
+Search is first done up the hierarchy, and if starting point is a Context
+then it is search in the Description hierarchy as well.</p>
+
+<p>This allows the user to declare and override values. Result being a very
+flexible configuration model. The flexibility could be the <em>Achilles</em>
+heel for the system as the search is expensive, specially for something that
+does not exist. Yet in the final analysis developers believe that the
+flexibility would serve better in this instant.</p>
+
+<table width="955" border="1" cellpadding="2" cellspacing="3">
+  <col width="112"><col width="371"><col width="103"><col width="336"><tbody>
+    <tr>
+      <td><strong>Context</strong></td>
+      <td><strong>Description</strong></td>
+      <td><strong>Configuration</strong></td>
+      <td><strong>Description</strong></td>
+    </tr>
+    <tr>
+      <td width="112"><p>Configuration Context</p>
+      </td>
+      <td width="371"><p>Holds the run time status. A deep copy of this would
+        essentially make a copy of Axis2.</p>
+      </td>
+      <td width="103"><p>Axis Configuration</p>
+      </td>
+      <td width="336"><p>Holds all global configurations. Transports, global
+        modules, parameters and Services etc.</p>
+      </td>
+    </tr>
+    <tr>
+      <td width="112"><p>Service Group Context</p>
+      </td>
+      <td width="371"><p>Holds information about a particular usage of the
+        respective service group. The life of a Service Group Context starts
+        when a user starts interacting with a service that belong to this
+        service group. This can be used to share information between services
+        (within the same service group) in a single interaction.</p>
+      </td>
+      <td width="103"><p>AxisServiceGroup</p>
+      </td>
+      <td width="336"><p>Holds deployment time information about a particular
+        service group.</p>
+      </td>
+    </tr>
+    <tr>
+      <td width="112"><p>Service Context</p>
+      </td>
+      <td width="371"><p>This context is available throughout the usage of
+        the respective service. This can be used to share information between
+        several MEPs of the same service, within a single interaction.</p>
+      </td>
+      <td width="103"><p>AxisService</p>
+      </td>
+      <td width="336"><p>Hold the Operations and the service level
+        configurations</p>
+      </td>
+    </tr>
+    <tr>
+      <td width="112"><p>Operation Context</p>
+      </td>
+      <td width="371"><p>Holds the information about the current MEP
+        instance, maintain the Messages in the current MEP etc.</p>
+      </td>
+      <td width="103"><p>AxisOperation</p>
+      </td>
+      <td width="336"><p>Holds the operation level configurations</p>
+      </td>
+    </tr>
+    <tr>
+      <td width="112"><a name="messageContext"></a>
+
+        <p>Message Context</p>
+      </td>
+      <td width="371"><p>Holds all the information about the Message
+        currently being executed.</p>
+      </td>
+      <td width="103"><p>AxisMessage</p>
+      </td>
+      <td width="336"><p>Do not hold any information as yet, but can be used
+        as a future extension point.</p>
+      </td>
+    </tr>
+  </tbody>
+</table>
+<a name="bmXML"></a>
+
+<h2>XML Processing Model</h2>
+
+<p>Please refer to the <a href="OMTutorial.html">OM Tutorial</a></p>
+
+<h2><a name="bmSOAPPM">SOAP Processing Model</a></h2>
+
+<p><img src="images/archi-guide/soap-processing.gif" name="Graphic4" alt=""
+align="bottom" width="755" height="348" border="0"></p>
+
+<p>The architecture identified two basic actions a SOAP processor should
+perform, sending and receiving SOAP messages. The architecture provides two
+Pipes ('Flows'), to perform these two basic actions. Axis Engine or the
+driver of Axis2 defines two methods send() and receive() to implement these
+two Pipes. The two pipes are named <i>In Pipe</i> and <i>Out Pipe</i>, and
+the complex Message Exchange Patterns (MEPs) are constructed by combining
+these two pipes.</p>
+
+<p>Extensibility of the SOAP processing model is provided through handlers.
+When a SOAP message is being processed the handlers that are registered would
+be executed. The handlers can be registered in global, service, or operation
+scopes and the final handler chain is calculated combining the handlers from
+all the scopes.</p>
+
+<p>The handlers act as interceptors and they process parts of the SOAP
+message and provide add-on services. Usually handlers work on the SOAP
+headers yet they may access or change the SOAP Body as well.</p>
+
+<p>When a SOAP message is being sent through the Client API, an <i>Out
+Pipe</i> would begin, the <i>Out Pipe</i> invokes the handlers and end with a
+Transport Sender that sends the SOAP message to the target endpoint. The SOAP
+message is received by a Transport Receiver at the target endpoint, which
+reads the SOAP message and starts the <i>In Pipe</i>. The <em>In Pipe</em>
+consists of handlers and ends with the <a href="#mr">Message Receiver</a>,
+which consumes the SOAP message.</p>
+
+<p>Above explained processing happens for each and every SOAP message
+exchanged. After processing one message Axis2 may decide to create other SOAP
+messages, in which case more complex message patterns emerge. However Axis2
+always view the SOAP message in terms of processing a single message. The
+combination of the messages are layered on top of that basic framework.</p>
+
+<p>The two pipes does not differentiate between the Server and the Client.
+The SOAP Processing Model handles the complexity and provides two abstract
+pipes to the user. The different areas or the stages of the pipes are given
+names, and according to the Axis2 slang those are named 'phases'. A Handler
+always runs inside a phase, and the phase provides a mechanism to specify the
+ordering of handlers. Both Pipes have built in phases, and both define the
+areas for 'User Phases' which can be defined by the user.</p>
+
+<p>Following figure shows the two pipes with their pre-defined phases &amp;
+user-defined phases. User-defined phases fit in to the User Phases.</p>
+
+<p><img src="images/archi-guide/phases.png" name="Graphic5" align="bottom"
+alt="" width="525" height="226" border="0"></p>
+
+<h3><a name="default">Axis2 Default Processing Model</a></h3>
+
+<p>Axis2 has some inbuilt handlers that run in inbuilt phases and they create
+the default configuration for the Axis2. We will be looking more in to how to
+extend the default processing Model in the next section.</p>
+There are four special handlers defined in Axis2.
+<ol>
+  <li>Dispatchers - Finds the service and the operation the SOAP message is
+    directed to. Dispatchers always run on the <em>In-Pipe</em> and inside
+    the Dispatch phase. The in-built dispatchers dispatch to a particular
+    operation depending on various conditions like WS-Addressing information,
+    URI information, SOAP action information, etc.,</li>
+</ol>
+<ul>
+  <li><a name="mr">Message Receiver - Consume the SOAP Message And hands that
+    over to application , Message receiver is the last handler of the
+    in-pipe</a></li>
+  <li><p>Transport Sender - Send the SOAP message to the SOAP endpoint the
+    message is destined to. Always runs as last handler in the out-pipe</p>
+  </li>
+</ul>
+
+<h3><a name="incomingsoap">Processing an Incoming SOAP Message</a></h3>
+
+<p>Incoming SOAP Message is always received by a Transport Receiver waiting
+for the SOAP Messages. Once the SOAP Message arrives the transport Headers
+are parsed and a</p>
+<a href="#messageContext">Message Context</a> is created for the incoming
+SOAP Message. Then the <i>In Pipe</i> is executed with the Message Context.
+
+<p>Let us see what happens at each phase of the execution. This process may
+happen either in the server or in the Client.</p>
+<ol>
+  <li>Transport Phase - The handlers are in the phase ment to be process
+    transport specific information such as validate incoming message by
+    looking at various transport headers, add data into message context
+  etc..</li>
+  <li>Pre-Dispatch Phase- The main functionality of the handlers are in this
+    phase is to populate message context in order to do the dispatching. As
+    an example processing of addressing headers happen in this phase , so by
+    looking at addressing headers it will find the name of the service and
+    operation.</li>
+  <li>Dispatch Phase - The Dispatchers run in this phase and find the Service
+    if the service is not found already. <br>
+    The post condition of the dispatch phase work as follows; That checks
+    whether the service and operation are found or not. If the service or
+    operation has not been found by this point the execution will halt and
+    send a "service not found error".</li>
+  <li>User Defined Phases - Users are allowed to engage their custom handlers
+    here.</li>
+  <li>Message Validation Phase - Once the user level execution has taken
+    place this phase validates whether SOAP Message Processing has taken
+    place correctly.</li>
+  <li>Message Processing Phase - The Business logic of the SOAP message is
+    executed here. A <a href="#mr">Message Receiver</a> is registered with
+    each Operation. This Message receiver (associated to the particular
+    operation) will executed as the last Handler of this phase.</li>
+</ol>
+
+<p>There may be other handlers in any of these phases. Users may use custom
+handlers to override the mechanics in each of these phases.</p>
+
+<h3><a name="outgoing">Processing of the Outgoing Message</a></h3>
+
+<p><em>Out Pipe</em> is simpler because the service and operation to dispatch
+is known by the time the pipe is executed. The <em>Out Pipe</em> may be
+initiated by the</p>
+<a href="#mr">Message Receiver</a> or the Client API implementation.Phases of
+the <em>Out Pipe</em> are described below:
+<ol>
+  <li>Message Initialize Phase - Fist phase of the <em>Out Pipe</em>. Serves
+    as the placeholder for the custom handlers</li>
+  <li>User Phases - This executes handlers in user defined phases</li>
+  <li>Transports Phase - Execute any transport handlers taken from the
+    associated transport configuration. The last handler would be a transport
+    Sender which would send the SOAP message to the target end point.</li>
+</ol>
+
+<h3><a name="extending">Extending SOAP Processing Model</a></h3>
+
+<p>Above we discussed the default processing model of Axis2. Now lets discuss
+the extension mechanism for the SOAP processing model. After all, the whole
+effort of making this SOAP engine/processing model was focused much on making
+it extendable.</p>
+
+<p>Idea behind introducing step wise processing of the SOAP message in terms
+of handlers &amp; phases is to allow easier modification of the processing
+order. The notion of phases makes it easier to place handlers in between
+other handlers enabling this modification on the default processing behavior.
+SOAP Processing Model can be extended with handler or Modules.</p>
+<a name="extendingwithhandlers"></a>
+
+<h4>Extending the SOAP Processing Model with Handlers</h4>
+The handlers in a module can specify the phase they need to be placed in.
+Furthermore they can specify their location inside a phase by providing phase
+rules. Phase rules will place a handler
+<ol>
+  <li>as the first handler in a phase.</li>
+  <li>or as the last handler in a phase.</li>
+  <li>or before a given handler</li>
+  <li>or after a given handler</li>
+</ol>
+
+<h4><a name="extendingwithmodules">Extending the SOAP Processing Model with
+Modules</a></h4>
+
+<p>Axis2 defines an entity called a 'module' that can introduce handlers and
+web service operations. A Module in terms of Axis2 usually acts as a
+convenient packaging that include a set of handlers and an associated
+descriptor which includes the phase rules. Modules have the concept of being
+'available' and 'engaged'. 'Availability' means the module is present in the
+system, but has not been activated, i.e., the handlers included inside the
+module have not been used in the processing mechanism. When a module is
+'engaged' it becomes active and the handlers get placed in the proper phases.
+The handlers will act in the same way as explained in the previous section.
+Usually a module will be used to implement a WS-* functionality such as
+WS-Addressing.</p>
+
+<p>Apart from the extension mechanism based on the handlers the WS-*
+specifications suggest a requirement for adding new operations. For example,
+once a user add a Reliable Messaging capability to a Service the "Create
+Sequence" operation needs to be available to the service end point. This can
+be implemented by letting the modules define the operations, and once the
+module is engaged to a service, the necessary operations will be added to
+that service.</p>
+
+<p>A service, operations or the system may engage a module. Once the module
+is engaged the handlers and the operations defined in the module are added to
+the entity that engage them.</p>
+
+<p>Modules can not be added while the Axis2 engine is running, but they will
+be available once the system is restarted.</p>
+<a name="bmDeployment"></a>
+
+<h2>Deployment</h2>
+
+<p>The Deployment Model provides a concrete mechanism to configure Axis2.
+This model has three entities that provide the configuration.</p>
+<a name="xmlfile"></a>
+
+<h3>The axis2.xml file</h3>
+
+<p>This file holds the global configuration for the client and server, and
+provide following information:</p>
+<ol>
+  <li>The global parameters</li>
+  <li>Registered transports in and transport outs</li>
+  <li>User defined phase names</li>
+  <li>Modules that are engaged globally (to all services)</li>
+  <li>Globally defined <a href="#mr">Message Receivers</a></li>
+</ol>
+<a name="servicearchive"></a>
+
+<h3>Service Archive</h3>
+
+<p>Service archive must have a <em>META-INF/services.xml</em> file and may
+contain the dependent classes. The <em>services.xml</em> file has following
+information.</p>
+<ol>
+  <li>Service level parameters</li>
+  <li>Modules that are engaged Service level</li>
+  <li>Service Specific <a href="#mr">Message Receivers</a></li>
+  <li>Operations inside the Service</li>
+</ol>
+
+<h3><a name="modulearchive">Module Archive</a></h3>
+
+<p>Module archive must have a META-INF/module.xml file and dependent classes.
+The <em>module.xml</em> file has Module parameters and the Operations defined
+in the module.</p>
+
+<p>When the system is starting up Axis2 ask the deployment model to create a
+Axis Configuration. Deployment Model first finds the axis2.xml file and build
+the global configuration. Then it checks for the module archives and then for
+the service archives. After which the corresponding services and modules are
+added to the Axis Configuration. System will build Contexts on top of the
+Axis Configurations and then Axis2 is ready to send or receive the SOAP
+Message. Hot deployment is only allowed for the service, in which case a
+thread will check the repository repeatedly, and then add the service
+corresponding to the new found service archives to the repository.</p>
+<a name="bmClientAPI"></a>
+
+<h2>Client API</h2>
+
+<p>There are three parameters that decide the nature of the Web Service
+interaction.</p>
+<ol>
+  <li>Message Exchange Pattern (MEP)</li>
+  <li>The Behavior of the transport, whether it's One-Way or Two-Way</li>
+  <li>Synchronous/ Asynchronous behavior of the Client API</li>
+</ol>
+
+<p>Variations of the three parameters can result in indefinite number of
+scenarios, even though Axis2 is built on a core that support any messaging
+interaction, the developers were compelled to support only two most widely
+used Message Exchange Patterns (MEPs).</p>
+
+<p>Two supported transports are One-Way and the Request-Response scenarios in
+the Client API. The implementation is based on a class called
+<code>ServiceClient</code> and there are extensions for each MEP that Axis2
+Client API supports.</p>
+
+<h3><a name="oneway">One Way Messaging Support</a></h3>
+
+<p>The One-Way support is provided by the <code>fireAndForget</code> which
+provide by <code>ServiceClient</code> that provides a much simpler interface
+for the user. The Axis2 supports HTTP , SMTP and TCP transports. In the case
+of the HTTP transport the return channel is not used and the HTTP 202 OK is
+returned in the return Channel.</p>
+<a name="requestresponse"></a>
+
+<h3>Request Response Messaging Support</h3>
+
+<p>The Request-Response support is provided by the <code>sendReceive()</code>
+method in ServiceClient ,that provides a much simpler interface for the user.
+The Client API has four ways to configure a given Message Exchange</p>
+<ol>
+  <li>Blocking or Non-Blocking nature - this can be decided by using
+    <code>sendReceive()</code> or <code>sendReceiveNonBlocking()</code>
+    methods</li>
+  <li>Sender transport - transport used to send the SOAP Message</li>
+  <li>Listener transport - transport the Response is received</li>
+  <li>Use Separate Channel - determines whether the response is send over a
+    separate transport connection or not. This can be false only when sender
+    and listener transport is same and is a Two-Way transport.</li>
+</ol>
+
+<p>Depending on the values of the above four parameter, Axis2 behave
+differently.</p>
+<a name="bmTransports"></a>
+
+<h2>Transports</h2>
+
+<p>Axis2 has two basic constructs for transports, Transport Senders and
+Transport Receivers . These are accessed via the AxisConfiguration.</p>
+
+<p>The incoming transport is the transport via which the server side receives
+the message and the outgoing transport is decided based on the addressing
+information (wsa:ReplyTo and wsa:FaultTo). If addressing information is not
+available then the out going transport will be the outputstream of the
+incoming transport (if it is two-way transport).</p>
+
+<p>At the client side the user is free to specify the transport to be
+used.</p>
+
+<p>Transport Senders and Transport Receivers contains following
+information.</p>
+<ol>
+  <li>Transport Sender for Out Configuration</li>
+  <li>Transport Listener for In Configuration</li>
+  <li>Parameters of the transport</li>
+</ol>
+
+<p>Each and every transport Out Configuration defines a transport sender.
+Transport sender sends the SOAP Message over depending on its
+configuration.</p>
+
+<p>Transport receiver waits for the SOAP Messages and for each SOAP Message
+that arrives, it uses the <i>In Pipe</i> to process the SOAP Message.</p>
+
+<p>Axis2 Presently support the following transports:</p>
+<ol>
+  <li>HTTP - In HTTP transport the transport listener is a servlet or
+    org.apache.axis2.transport.http.SimpleHTTPServer provided by Axis2. The
+    transport sender uses commons-httpclient to connect and send the SOAP
+    Message.</li>
+  <li>TCP - This is the most simplest transport, but needs the WS -
+    Addressing support to be functional.</li>
+  <li>SMTP - This works off a single email account. Transport receiver is a
+    thread that checks for emails in fixed time intervals.</li>
+</ol>
+<a name="bmWSDL" id="bmWSDL"></a>
+
+<h2>Code generation</h2>
+
+<p>Although the basic objective of the code generation tool has not changed,
+the code generation module of Axis2 has taken a different approach to
+generate code. Primarily the change is in the use of templates, namely XSL
+templates which gives the code generator the flexibility to generate code in
+multiple languages.</p>
+
+<p>The basic approach is to set the code generator to generate an XML and
+parse it with a template to generate the code file. The following figure
+describes how this shows up in the architecture of the tool.</p>
+
+<p><img src="images/archi-guide/CodegenArchitecture.jpg" name="Graphic6"
+alt="" align="bottom" width="478" height="218" border="0"></p>
+
+<p>The fact here is that it is the same information that is extracted from
+the WSDL no matter what code is generated. Code generator uses the WOM (WSDL
+Object Model) internally to manipulate the WSDL and passes that information
+to the emitter which emits an XML. The XML is then parsed with the relevant
+XSL to generate the code. No matter what the language, the process is the
+same except for the template that is being used</p>
+
+<h2><a name="bmDB" id="bmDB">Data Binding</a></h2>
+<a name="integration"></a>
+
+<h3>Integration with the code generation engine</h3>
+
+<p>Axis2 M2 was released with code generation support but without data
+binding. The version 0.9 was shipped with data binding support with complete
+schema support. Such claim is made possible because of the fact that the data
+binding tool, xml-beans, has the full schema support. The original
+architecture of the code generation framework did not undergo significant
+changes because of the way that the code generation framework was originally
+designed. Data binding was incorporated as a pluggable extension to the code
+generation engine. Axis2 version 0.91 does not support SOAP encoding. It only
+supports RPC literal or document literal massages.</p>
+
+<p><img src="images/codegen.gif" name="Graphic7" align="bottom" width="406"
+alt="" height="467" border="0"></p>
+
+<h3><a name="serial">Serialization and De-Serialization</a></h3>
+
+<p>AXIOM is based on a StAX (Streaming API for XML) API. Xml-beans supports
+StAX API. Data binding in Axis2 is achieved through interfacing the AXIOM
+with the Xml-beans using the StAX API which is supported by both parties. At
+the time of the code generation there will be supporter classes for each WSDL
+operation that will have the utility methods that can de-serialize the from
+AXIOM to data bound object and serialize from data bound object to AXIOM. For
+example if the WSDL has an operation called "echoString", once the code is
+generated there will be an echoStringDatabindingSupporter.java class
+generated that will have methods that will look like the following.</p>
+
+<p><code>public static
+org.apache.axiom.om.OMElementtoOM(org.soapinterop.xsd.EchoStringParamDocument
+param)</code><code>// This method will handle the serialization.</code></p>
+
+<p><code>public static org.apache.xmlbeans.XmlObject
+fromOM(org.apache.axis2.om.OMElement param, java.lang.Class type) //This
+method will handle the de-serialization.</code></p>
+
+<p><code>public static org.apache.xmlbeans.XmlObject
+getTestObject(java.lang.Class type) /*This will be a utility method that can
+be used to create sample objects of the given data bound object.*/</code></p>
+
+<p></p>
+</body>
+</html>

Modified: webservices/axis2/trunk/java/xdocs/latest/ServiceArchiveToolReference.html
URL: http://svn.apache.org/viewcvs/webservices/axis2/trunk/java/xdocs/latest/ServiceArchiveToolReference.html?rev=396498&r1=396497&r2=396498&view=diff
==============================================================================
--- webservices/axis2/trunk/java/xdocs/latest/ServiceArchiveToolReference.html (original)
+++ webservices/axis2/trunk/java/xdocs/latest/ServiceArchiveToolReference.html Mon Apr 24 03:03:34 2006
@@ -9,11 +9,11 @@
 
 <p><a href="http://ws.apache.org/axis2/download.cgi">[Download]</a></p>
 
-<p>Axis2 comes with a simple service archiver tool. This tool provides easy
-to use functionality to develop an Axis archive or an "aar" file or a "jar"
-file that can be deployed as a web service to the Axis2. This tool is in the
-form of an Eclipse plug-in and can be downloaded from the downloads section.
-This document describes how the tool can be used.</p>
+<p>Axis2 comes with a simple service archive tool. This tool provides easy to
+use functionality to develop an Axis archive or an "aar" file or a "jar" file
+that can be deployed as a web service to the Axis2. This tool is in the form
+of an Eclipse plug-in and can be downloaded from the downloads section. This
+document describes how the tool can be used.</p>
 
 <h2>Installation</h2>
 
@@ -34,11 +34,11 @@
 <p>Selecting the wizard and pressing the next button will start the service
 generator wizard. Following is the first wizard page.</p>
 
-<p align="center"><img alt="" border="0" src="images/tools/service/ServicePage1.jpg"
-width="500" height="500"></p>
+<p align="center"><img alt="" border="0"
+src="images/tools/service/ServicePage1.jpg" width="500" height="500"></p>
 
 <p>Once the class file folder is given (which should be a folder in the file
-system) the next button will be enabled. </p>
+system) the next button will be enabled.</p>
 
 <p>Page 2 of the wizard requires you to locate the wsdl file. Note that the
 WSDL file cannot be skipped in this version of the tool.</p>
@@ -138,7 +138,8 @@
 <p>The plugin also adds a help document to the Eclipse help system. You
 should see it if you go to Eclipse help content</p>
 
-<p align="center"><img alt="" border="0" src="images/tools/service/help.JPG"></p>
+<p align="center"><img alt="" border="0"
+src="images/tools/service/help.JPG"></p>
 <hr>
 
 <p></p>



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