PROPOSAL.html

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<title>Proposal for BeanUtils Package</title>
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<h1>Proposal for <em>BeanUtils</em> Package</h1>
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<h3>(0) Rationale</h3>

<p>Most Java developers are used to creating Java classes that conform to the
JavaBeans naming patterns for property getters and setters.  It is natural to
then access these methods directly, using calls to the corresponding
<code>getXxx</code> and <code>setXxx</code> methods.  However, there are some
occasions where dynamic access to Java object properties (without compiled-in
knowledge of the property getter and setter methods to be called) is needed.
Example use cases include:</p>
<ul>
<li>Building scripting languages that interact with the Java object model
    (such as the Bean Scripting Framework).</li>
<li>Building template language processors for web presentation and similar
    uses (such as JSP or Velocity).</li>
<li>Building custom tag libraries for JSP and XSP environments (such as Jakarta
    Taglibs, Struts, Cocoon).</li>
<li>Consuming XML-based configuration resources (such as Ant build scripts, web
    application deployment descriptors, Tomcat's <code>server.xml</code>
    file).</li>
</ul>

<p>The Java language provides <em>Reflection</em> and <em>Introspection</em>
APIs (see the <code>java.lang.reflect</code> and <code>java.beans</code>
packages in the JDK Javadocs).  However, these APIs can be quite complex to
understand and utilize.  The proposed <em>BeanUtils</em> component provides
easy-to-use wrappers around these capabilities.</p>


<h3>(1) Scope of the Package</h3>

<p>This proposal is to create a package of Java utility methods for accessing
and modifying the properties of arbitrary JavaBeans.  No dependencies outside
of the JDK are required, so the use of this package is very lightweight.</p>

<p>In addition to wrapping the reflection and introspection APIs of the
standard JDK, <em>BeanUtils</em> components shall support a syntax for directly
accessing <strong>nested</strong> and <strong>indexed</strong> properties, in a
manner that will be familar to users of scripting languages like JavaScript.
For example, the following property accessor expressions are supported:</p>
<ul>
<li><strong>customer</strong> - Equivalent to <code>getCustomer()</code>.</li>
<li><strong>customer.address</strong> - Equivalent to
    <code>getCustomer().getAddress()</code>.</li>
<li><strong>customer.address[2].street</strong> - Equivalent to
    <code>getCustomer().getAddress(2).getStreet()</code> (access to indexed
    properties also works if the underlying property is an array rather than
    providing indexed getter and setter methods).</li>
</ul>


<h3>(1.5) Interaction With Other Packages</h3>

<p><em>BeanUtils</em> relies only on standard JDK 1.2 (or later) APIs for
production deployment.  It utilizes the JUnit unit testing framework for
developing and executing unit tests, but this is of interest only to
developers of the component.  BeanUtils will also be a dependency for
several future proposed components for the Jakarta Commons subproject.</p>

<p>No external configuration files are utilized.</p>


<h3>(2) Initial Source of the Package</h3>

<p>The three original Java classes (<code>BeanUtils</code>,
<code>ConvertUtils</code>, and <code>PropertyUtils</code>) are an integral
part of the <a href="http://jakarta.apache.org/struts">Struts Framework</a>.
However, they have very few dependencies on other aspects of Struts, and
those dependencies have been removed in the proposed code base.
Once accepted and released as a Jakarta Commons component, Struts will
be modified to use the Commons version of these classes, and its internal
versions will be deprecated.</p>

<p>The proposed package name for the new component is
<code>org.apache.commons.beanutils</code>.</p>


<h3>(3)  Required Jakarta-Commons Resources</h3>

<ul>
<li>CVS Repository - New directory <code>beanutils</code> in the
    <code>jakarta-commons</code> CVS repository.  All initial committers
    are already committers on <code>jakarta-commons</code>, so no
    additional user setups are required.</li>
<li>Mailing List - Discussions will take place on the general
    <em>jakarta-commons@jakarta.apache.org</em> mailing list.  To help
    list subscribers identify messages of interest, it is suggested that
    the message subject of messages about this component be prefixed with
    [BeanUtils].</li>
<li>Bugzilla - New component "BeanUtils" under the "Commons" product
    category, with appropriate version identifiers as needed.</li>
<li>Jyve FAQ - New category "commons-beanutils" (when available). </li>
</ul>


<h3>(4) Initial Committers</h3>

<p>The initial committers on the BeanUtils component shall be Craig
McClanahan and Geir Magnusson Jr.</p>



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