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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<title>JiBX: CodeGen Tool</title>
</head>
<body class="composite">
<div id="bodycol">
<div class="app">
<div class="h3">
<h3><a name="intro"></a>CodeGen tool</h3>
<p>CodeGen is the tool used to generate Java code and a binding definition from an
XML schema. It currently handles most types of schema definitions, but as with most
data binding tools some aspects of schema with are not completely supported. These
unsupported or partially-supported schema features including the following:</p>
<ul>
<li>Schemas using <xs:any> extension points, where the <xs:any> is not the last
item in a sequence. Most often <xs:any> is used at the end of a content model, since
that way it can be used to provide compatiblity with future extensions of the model
adding more details to the content model. It doesn't have to be used in this way, though,
and in particular it can be used anywhere within a content model if it has the attribute
<code>namespace="##other"</code>. This usage is not currently supported by CodeGen.</li>
<li>Schemas using <xs:anyAttribute> extension points. <xs:anyAttribute> handling is
not yet implemented by CodeGen, and is unlikely to be supported until JiBX version 2.0.</li>
<li>minOccurs values other than "0" or "1", maxOccurs values other than "1" or "unbounded";
CodeGen treats any maxOccurs value greater than "1" as equivalent to "unbounded" (and
ignores the minOccurs value in this case, allowing <i>any</i> number of occurrences,
including none). It also treats minOccurs values greater than "1" as equivalent to "1".
This means that there are really only three variations of minOccurs/maxOccurs generated
by CodeGen: Optional components, with minOccurs="0" and maxOccurs="1"; required
components, with minOccurs="1" and maxOccurs="1"; and repeating components, with
maxOccurs greater than "1".</li>
<li><xs:union> simple type derivations are currently handled as simple string values</li>
<li>The only type of simple type <xs:restriction> facet currently processed by CodeGen
is the <xs:enumeration> facet.</li>
</ul>
</div>
<div class="h3">
<h3>Running CodeGen</h3>
<p>CodeGen executes as a Java application, meaning it needs to be run directly from a
console window using the "java" command, or though some equivalent technique (such as
an Ant <code><java></code> task, discussed below). However it's being run, you need
to include <i>jibx-tools.jar</i> from your JiBX installation <i>lib</i> directory in the
Java classpath. You'll also need several of the other jars from the JiBX <i>lib</i>
directory (including <i>jibx-bind.jar</i>, <i>jibx-schema.jar</i>, and <i>jibx-run.jar</i>,
along with <i>log4j.jar</i> and all the eclipse jars). As long as these jars are in the
same directory as <i>jibx-tools.jar</i> you don't need to list them in the classpath,
though - they'll be picked up automatically.</p>
<p>The CodeGen application main class is <code>org.jibx.schema.codegen.CodeGen</code>,
and it takes as parameters the names or name patterns (using '*' wildcard characters) for
schemas to be used as the basis for code generation. Only "top-level" schemas need to be
specified; schemas referenced by means of xs:include or xs:import will automatically be
loaded by CodeGen and included in the code generation.</p>
<p>Here's a sample of running CodeGen on Unix/Linux systems from the <i>examples/codegen</i>
directory of the distribution (in a single line, shown split here only for formatting):</p>
<div id="source"><pre>java -cp ../../lib/jibx-tools.jar org.jibx.schema.codegen.CodeGen
otasubset/OTA_AirLowFareSearchRQ.xsd</pre></div>
<p>On Windows, the corresponding command line is:</p>
<div id="source"><pre>java -cp ..\..\lib\jibx-tools.jar org.jibx.schema.codegen.CodeGen
otasubset\OTA_AirLowFareSearchRQ.xsd</pre></div>
<p>By default, CodeGen output just goes to the current directory where it was executed. The
generated root binding definition is named <i>binding.xml</i>, and the generated Java package(s)
is derived from the schema namespace.</p>
<p>When working with large schemas you may find performance to be a problem using the
standard JVM memory settings. You should be able to dramatically improve performance by
increasing your Java runtime memory settings (with the JVMs provided by Sun this is done
using the <i>-Xms</i> and <i>-Xmx</i> command line flags, so passing the command line
parameters <code>-Xms512M -Xmx512M</code> would increase the memory available to the JVM
from the standard 16 megabytes to 512 megabytes).</p>
</div>
<div class="h3">
<h3>Using build tools</h3>
<p>You can easily run CodeGen from an Ant build, just as you would any other Java application.
The <i>build.xml</i> in the <i>examples/codegen</i> directory gives an example of this
(which passes an optional generation directory path parameter, in addition to a schema
file path pattern), as shown below:</p>
<div id="source"><pre> <!-- set classpath for compiling and running application with JiBX -->
<path id="classpath">
<fileset dir="${jibx-home}/lib" includes="*.jar"/>
<pathelement location="bin"/>
</path>
...
<!-- generate using default settings -->
<target name="codegen" depends="check-runtime,clean">
<echo message="Running code generation from schema"/>
<java classname="org.jibx.schema.codegen.CodeGen" fork="yes"
classpathref="classpath" failonerror="true">
<arg value="-t"/>
<arg value="gen/src"/>
<arg value="otasubset/OTA_AirLowFareSearch*.xsd"/>
</java>
</target></pre></div>
<p>Most IDEs allow you to directly execute an Ant build target, so you can use the Ant
approach to running CodeGen from within your IDE.</p>
<p>You can change the default memory size for the <java> Ant task using nested
<jvmarg> parameters. By way of example, here's how you'd change the above Ant target
to use 512 megabytes of memory:</p>
<div id="source"><pre> <java classname="org.jibx.schema.codegen.CodeGen" fork="yes"
classpathref="classpath" failonerror="true">
<jvmarg value="-Xms512M"/>
<jvmarg value="-Xmx512M"/>
<arg value="-t"/>
<arg value="gen/src"/>
<arg value="otasubset/OTA_AirLowFareSearch*.xsd"/>
</java></pre></div>
</div>
<div class="h3">
<h3>Command line parameters</h3>
<p>You can pass a variety of command line parameters to CodeGen, as listed below in
alphabetical order:</p>
<table cellpadding="3" cellspacing="2" border="1" width="100%">
<tr class="b">
<th scope="col">Parameter</th>
<th scope="col">Purpose</th>
</tr>
<tr class="a">
<td><code>-b name</code></td>
<td>Generated root binding definition file name (default name is binding.xml)</td>
</tr>
<tr class="b">
<td><code>-c path</code></td>
<td>Path to input customizations file</td>
</tr>
<tr class="a">
<td><code>-i path1,path2,...</code></td>
<td>Include existing bindings and use mappings from the bindings for matching schema
global definitions (this is the basis for <a href="%cgexample4%">modular code generation</a>)</td>
</tr>
<tr class="b">
<td><code>-n package</code></td>
<td>Default package for code generated from schema definitions with no namespace
(default is the package "dflt", if not set)</td>
</tr>
<tr class="a">
<td><code>-p package</code></td>
<td>Default package for code generated from all schema definitions</td>
</tr>
<tr class="b">
<td><code>-s path</code></td>
<td>Root directory path for schema definitions (so that simple names can be used when
specifying multiple schemas)</td>
</tr>
<tr class="a">
<td><code>-t path</code></td>
<td>Target directory path for generated output (default is current directory)</td>
</tr>
<tr class="b">
<td><code>-u uri</code></td>
<td>Namespace applied in code generation when no-namespaced schema definitions are
found (to generate no-namespaced schemas as though they were included in a particular
namespace)</td>
</tr>
<tr class="a">
<td><code>-v</code></td>
<td>Verbose output</td>
</tr>
<tr class="b">
<td><code>-w</code></td>
<td>Wipe all files from target directory before generating output (ignored if the target directory is the same as the current directory)</td>
</tr>
</table>
<p>You need to specify one or more schema paths or file path patterns as command
line parameters to CodeGen. Each schema you specify is used as a starting point for
generating code and binding definitions. CodeGen examines each specified schema to
find references to other schemas, and then recursively examines the referenced schemas,
to find the complete set of schemas used to represent the data. It then generates code
and binding definitions for all of these schemas. The schema names or file path
patterns must be at the end of the command line, following any other command line
parameters. '*' wildcard characters can be used in schema names, but only as part of
file paths. Schema names can also be specified using HTTP or other forms of URLs, but
wildcard characters are not allowed in this case.</p>
<p>Finally, you can pass global customizations to CodeGen as command-line parameters,
by using <code>--</code> as a special prefix to the customization attribute name.
This is explained in more detail in the CodeGen <a href="%cgcustoms%#command">customization
reference page</a>. Before digging into the details of customizations you may find
it useful to review the CodeGen <a href="%cgexamples%">examples</a> to learn how CodeGen
works and see some basic applications of customizations.</p>
</div>
<div class="h3">
<h3><a name="logging"></a>Logging support</h3>
<p>CodeGen includes logging code at a variety of levels of detail, using the <i>log4j</i>
library. The <i>jibx-tools.jar</i> includes a default <i>log4j.properties</i> which
only supports ERROR level logging, with output to the console. This default properties
file can be overridden by another <i>log4j.properties</i> which is placed earlier in
the classpath. The <i>log4j.properties</i> file in the <i>examples/codegen</i>
directory is supplied as a sample, which can be activated by changing the classpath
definition in the Ant <i>build.xml</i> as follows:</p>
<div id="source"><pre> <!-- set classpath for compiling and running application with JiBX -->
<path id="classpath">
<pathelement location="."/>
<fileset dir="${jibx-home}/lib" includes="*.jar"/>
<pathelement location="bin"/>
</path></pre></div>
<p>This logging support is only intended for use by JiBX developers and others who
are investigating the operation of the CodeGen program. The logging information is
generally not useful to end users.</p>
</div>
</div>
</div>
</body>
</html>
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