Glyn,
If you haven't heard this enough already, it is VERY COOL that you are doing this documentation and architecture work for Axis. A big +1 for Glyn for taking this responsibility. -- Tom Jordahl Macromedia -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] Sent: Friday, February 01, 2002 9:21 AM To: [EMAIL PROTECTED] Subject: cvs commit: xml-axis/java/docs serclasses.jpg serfactoryclasses.jpg typemappingclasses.jpg typemappingregistryclasses.jpg architecture-guide.html glyn 02/02/01 06:20:30 Modified: java/docs architecture-guide.html Added: java/docs serclasses.jpg serfactoryclasses.jpg typemappingclasses.jpg typemappingregistryclasses.jpg Log: Describe encoding subsystem. Revision Changes Path 1.6 +51 -2 xml-axis/java/docs/architecture-guide.html Index: architecture-guide.html =================================================================== RCS file: /home/cvs/xml-axis/java/docs/architecture-guide.html,v retrieving revision 1.5 retrieving revision 1.6 diff -u -r1.5 -r1.6 --- architecture-guide.html 31 Jan 2002 16:12:04 -0000 1.5 +++ architecture-guide.html 1 Feb 2002 14:20:30 -0000 1.6 @@ -2,9 +2,7 @@ <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> - <meta name="GENERATOR" content="Mozilla/4.75 [en] (WinNT; U) [Netscape]"> <title>Axis Architecture Guide</title> -<!-- saved from url=(0022)http://internet.e-mail --> <style type="text/css"> <!-- .example { background:#ccccff } @@ -41,6 +39,7 @@ <br><a href="#Message Model Subsystem">Message Model Subsystem</a> <br> <a href="#SOAP message model">SOAP Message Model</a> <br> <a href="#Message elements">Message Elements</a> +<br><a href="#Encoding Subsystem">Encoding Subsystem</a> <br><a href="#WSDL Subsystem">WSDL Tools Subsystem</a> <br> <a href="#WSDL2Java">WSDL2Java</a> <br><a href="#Sequence Diagrams">Interaction Diagrams</a> @@ -315,6 +314,56 @@ the MessageElement class which takes care of namespaces and encodings. The SOAPHeader class looks after the actor and mustUnderstand attributes. <br><img SRC="messagemodelclasses.jpg"> + +<h2> +<a NAME="Encoding Subsystem"></a>Encoding Subsystem</h2> +Encoding is most easily understood from the bottom up. The basic +requirement is to transform between values of programming language +datatypes and their XML representations. In Axis, this means +encoding (or 'serializing') Java objects and primitives into XML +and decoding (or 'deserializing') XML into Java objects and primitives. +The basic classes that implement these steps are <i>serializers</i> +and <i>deserializers</i>. +<br><img SRC="serclasses.jpg"> +<p> +Particular serializers and deserializers are written to support +a specific XML processing mechanism such as DOM or SAX. +So <i>serializer factories</i> and <i>deserializer factories</i> +are introduced to construct serializers and deserializers +for a XML processing mechanism which is specified +as a parameter. +<br><img SRC="serfactoryclasses.jpg"> +<p> +As is apparent from the above class diagrams, each pair of Java +type and XML data type which needs encoding +and decoding requires specific serializers and +deserializers (actually one of each per XML processing mechanism). +So we need to maintain a mapping from a pair of Java type and XML data +type, identified by a QName, to a serializer factory and a +deserializer factory. +Such a mapping is known as a <i>type mapping</i>. +The type mapping class hierarchy is shown below. Notice how +the default type mapping instantiates the various serializer and +deserialiser factories. +<br><img SRC="typemappingclasses.jpg"> +<p> +There is one final level of indirection. How do we know +which type mapping to use for a particular message? +This is determined by the encoding which is specified in +the message. A <i>type mapping registry</i> maintains +a map from encoding name (URI) to type mapping. +Note that the XML data type QNames are defined by the encoding. +<br><img SRC="typemappingclasses.jpg"> +<p> +So, in summary, to encode a Java object or primitive data value +to a XML datatype or to decode the latter to the former, +we need to know: +<ul> +<li>the Java type we are dealing with,</li> +<li>the QName of the XML data type we want to encode it as,</li> +<li>the XML processing mechanism we are using, and</li> +<li>the encoding name.</li> +<eul> <h2> <a NAME="WSDL Subsystem"></a>WSDL Tools Subsystem</h2> 1.1 xml-axis/java/docs/serclasses.jpg <<Binary file>> 1.1 xml-axis/java/docs/serfactoryclasses.jpg <<Binary file>> 1.1 xml-axis/java/docs/typemappingclasses.jpg <<Binary file>> 1.1 xml-axis/java/docs/typemappingregistryclasses.jpg <<Binary file>>
