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 <h2>PROPOSAL</h2>

 <p><em>Updated 5 September 2002.</em></p>

 <p>This is a proposed roadmap for the further development of Expat.  The
 primary purpose for making this proposal is to determine whether our
 ideas for continued development are aligned with the needs of the
 community.  We welcome comment both from Expat users, would-be users,
 and members of the XML community who have decided against using Expat
 for technical reasons directly related to Expat.</p>

 <p>Discussion of this document should be directed to the <a href=
 "http://mail.libexpat.org/mailman-21/listinfo/" >expat-discuss</a>
 mailing list.</p>


 <h3>Goals</h3>

 <p>We do <strong>not</strong> plan to alter the goals of the Expat
 project.  We intend to continue to develop Expat to have the following
 qualities:</p>

 <ul>
 <li> Fast </li>

 <li> Conformant to XML 1.0 and Namespaces </li>

 <li> Easy to use from C </li>

 <li> Easy to wrap / bind for non-C languages </li>

 <li> Sufficient to build DOM and SAX on top of
      (any final specification for XML) </li>

 <li> Modest memory footprint </li>

 <li> Portable </li>
 </ul>


 <h3>Non-Goals</h3>

 <ul>
 <li> Parsing anything that isn't XML </li>

 <li> DOM (any level) </li>

 <li> SAX (any version) </li>

 <li> Data bindings </li>

 <li> Watching the kids </li>
 </ul>


 <h3>Historical Background</h3>

 <p>James Clark initially developed Expat, releasing three stable
 versions, identified as versions 1.0, 1.1, and 1.2.  Clark Cooper
 created a forked version of Expat based on Expat 1.1, for use in the
 XML::Parser extension module for Perl.</p>

 <p>As James Clark's interests shifted, and his development moved to
 the Java environment, the authors of 3rd party language bindings found
 it increasingly difficult to integrate Expat with their languages, and
 other developers found it difficult to get fixes accepted into Expat
 and released.  A small group of extension authors were gathered by
 Paul Prescod in the hope that Expat could be formed into a more
 readily usable library for both direct use in C-language applications
 and indirect use from other languages.  This group was led by Clark
 Cooper and Fred Drake, and received sanction to take over maintenance
 of Expat from James Clark.  The project is hosted on SourceForge.
 This group made their first release as Expat 1.95.0 in September
 2000.</p>

 <p>Since that time, incremental releases of Expat have been made on a
 sporadic schedule, improving functionality and portability with each
 release.</p>


 <h3>Expat Development Roadmap</h3>

 <p>Now that our goals and non-goals have been spelled out, let's take
 a look at how we should get there from where we are now.  This will be
 broken down into two stages: near future activities and far future
 activities.  In spite of the somewhat temporal labeling of these
 categories, please realize that no actual scheduling has been done,
 nor is that considered relevant at this time.  Actual time to meet
 these goals is dependent on the availability of resources to work on
 Expat.  Parallel development may also happen, depending on the
 specific interests of contributers.</p>

 <h4>Near Future Activity</h4>

 <p>The target of the current line of development will be to release Expat
 2.0.  The intent is that once Expat 2.0 is released, most of the
 development activity for this line will be maintenance, and will be
 driven by user-provided problem reports.  These are the goals for
 goals we have specific to the release of Expat 2.0:</p>

 <ul>
 <li> Stabilize the current API with some minor revisions to make error
      reporting more explicit to allow better reporting and diagnosis. </li>

 <li> Introduce a new feature-test macro, XML_MINIMAL, parallel to
      XML_DTD, XML_UNICODE, and XML_UNICODE_WCHAR_T.  Defining the new
      feature when compiling Expat will cause functions that are not
      relevant to the rest of the feature macros.  (For example, if
      XML_DTD is not set but XML_MINIMAL is, the functions that set
      handlers for DTD-related events won't be included at all.)  This
      is intended to make it easier to use Expat in small-memory
      devices. </li>

 <li> API revisions will be made to improve the runtime discoverability of
      Expat capabilities. </li>

 <li> Improve portability and performance. </li>

 <li> Substantially improve regression tests. </li>

 <li> Improve documentation. </li>

 <li> Full support for 64-bit platforms.  (There are some known decoding
      problems currently.) </li>
 </ul>

 <p>When we're confident that the minor API changes are "right", we'll
 finallize the API and release Expat 2.0.  Should additional functions
 be required as evolutionary improvements, the minor version number
 will be incremented, but all existing functions will be maintained for
 backward compatibility.  Releases that are strictly bug fixes will
 have the same minor version number and will gain a "micro" version
 number (sometimes called a "patch level").</p>


 <h4>Far Future Activity</h4>

 <p>Once Expat 2.0 has been released, it will be maintained on a CVS
 branch.  The head of CVS will be used to develop Expat 3.0.  The
 changes in Expat 3.0 will be more substantial and will include
 important API changes.  At this time, we're looking at the following
 changes:</p>

 <dl>
 <dt> More powerful event API </dt>
 <dd>
   <p>The new API will be sufficiently detailed that a complete and
   detailed DOM structure can be built, including both internal and
   external entity boundaries in parsed character data content,
   attribute value content, and entity values (such as found in
   internal entity declarations).</p>

   <p>This API will of necessity be somewhat more complex than the
   current API, but we expect the current API can be implemented on top
   of the new API.  For users for whom the Expat 2.0 API is
   sufficiently powerful, this API will remain available.</p>
 </dd>

 <dt> Support for either pull or suspendable parsing </dt>
 <dd>
   <p>The new API will need to support some way to interrupt processing
   without having to parse all XML text passed to the parser so far.
   This can be done by either using a pull-based model or a push-based
   model (similar to the current API) with the added ability to suspend
   parsing on request.</p>

   <p>The specific API will depend on the model selected; either a
   pull-based model or an suspension model can support each other with
   little additional work, and the current push model can be built on
   top of either.</p>

   <p>The specific model and API will be discussed on the <a href=
   "http://mail.libexpat.org/mailman-21/listinfo/" >expat-discuss</a>
   mailing list.</p>
 </dt>

 <dt> New encoding support </dt>
 <dd>
   <p>A new library may be added to the Expat package that provides a
   flexible architecture for defining new encodings, and provides a
   large range of common encodings.  (It should be possible to develop
   this so that it supports both Expat 2.0 and Expat 3.0.)</p>

   <p>Another approach which will be considered will be to support
   Expat's requirements for decoders using one of the existing open
   source encoding support libraries that meets Expat's requirements
   for portability.  Possible technical approaches would include
   implementing an adapter, and developing such an external library to
   include direct support for the kind of interface support Expat
   needs.</p>
 </dd>

 <dt> <a href= "http://www.w3.org/TR/xml11/" >XML 1.1</a> (including <a
   href="http://www.w3.org/TR/xml-names11/" >Namespaces in XML
   1.1</a>), if it ever happens </dt>
 <dd>
   <p>Well, we're hoping, but it's not time to code for this yet.</p>
 </dd>
 </dl>

 <p>Additional goals may be added during the development of Expat 3.0;
 it's just too early to tell.</p>


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	<html>
	<head>
	<title>Expat Development Roadmap</title>
	<link rel="STYLESHEET" href="../style.css" type="text/css" />
	</head>
	<body marginwidth="0" marginheight="0">
	<table cellspacing="0" cellpadding="0" width="100%">
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	<td class="corner"><a href="../"><img src="../expat.png"
	border="0"/></a></td>
	<td class="banner"><h2>Expat Development Roadmap</h2></td>
	</tr>
	<tr>
	<td class="navbar">
	</td>
	<td class="content">

	<h2>PROPOSAL</h2>

	<p><em>Updated 5 September 2002.</em></p>

	<p>This is a proposed roadmap for the further development of Expat. The
	primary purpose for making this proposal is to determine whether our
	ideas for continued development are aligned with the needs of the
	community. We welcome comment both from Expat users, would-be users,
	and members of the XML community who have decided against using Expat
	for technical reasons directly related to Expat.</p>

	<p>Discussion of this document should be directed to the <a href=
	"http://mail.libexpat.org/mailman-21/listinfo/" >expat-discuss</a>
	mailing list.</p>


	<h3>Goals</h3>

	<p>We do <strong>not</strong> plan to alter the goals of the Expat
	project. We intend to continue to develop Expat to have the following
	qualities:</p>

	<ul>
	<li> Fast </li>

	<li> Conformant to XML 1.0 and Namespaces </li>

	<li> Easy to use from C </li>

	<li> Easy to wrap / bind for non-C languages </li>

	<li> Sufficient to build DOM and SAX on top of
	(any final specification for XML) </li>

	<li> Modest memory footprint </li>

	<li> Portable </li>
	</ul>


	<h3>Non-Goals</h3>

	<ul>
	<li> Parsing anything that isn't XML </li>

	<li> DOM (any level) </li>

	<li> SAX (any version) </li>

	<li> Data bindings </li>

	<li> Watching the kids </li>
	</ul>


	<h3>Historical Background</h3>

	<p>James Clark initially developed Expat, releasing three stable
	versions, identified as versions 1.0, 1.1, and 1.2. Clark Cooper
	created a forked version of Expat based on Expat 1.1, for use in the
	XML::Parser extension module for Perl.</p>

	<p>As James Clark's interests shifted, and his development moved to
	the Java environment, the authors of 3rd party language bindings found
	it increasingly difficult to integrate Expat with their languages, and
	other developers found it difficult to get fixes accepted into Expat
	and released. A small group of extension authors were gathered by
	Paul Prescod in the hope that Expat could be formed into a more
	readily usable library for both direct use in C-language applications
	and indirect use from other languages. This group was led by Clark
	Cooper and Fred Drake, and received sanction to take over maintenance
	of Expat from James Clark. The project is hosted on SourceForge.
	This group made their first release as Expat 1.95.0 in September
	2000.</p>

	<p>Since that time, incremental releases of Expat have been made on a
	sporadic schedule, improving functionality and portability with each
	release.</p>


	<h3>Expat Development Roadmap</h3>

	<p>Now that our goals and non-goals have been spelled out, let's take
	a look at how we should get there from where we are now. This will be
	broken down into two stages: near future activities and far future
	activities. In spite of the somewhat temporal labeling of these
	categories, please realize that no actual scheduling has been done,
	nor is that considered relevant at this time. Actual time to meet
	these goals is dependent on the availability of resources to work on
	Expat. Parallel development may also happen, depending on the
	specific interests of contributers.</p>

	<h4>Near Future Activity</h4>

	<p>The target of the current line of development will be to release Expat
	2.0. The intent is that once Expat 2.0 is released, most of the
	development activity for this line will be maintenance, and will be
	driven by user-provided problem reports. These are the goals for
	goals we have specific to the release of Expat 2.0:</p>

	<ul>
	<li> Stabilize the current API with some minor revisions to make error
	reporting more explicit to allow better reporting and diagnosis. </li>

	<li> Introduce a new feature-test macro, XML_MINIMAL, parallel to
	XML_DTD, XML_UNICODE, and XML_UNICODE_WCHAR_T. Defining the new
	feature when compiling Expat will cause functions that are not
	relevant to the rest of the feature macros. (For example, if
	XML_DTD is not set but XML_MINIMAL is, the functions that set
	handlers for DTD-related events won't be included at all.) This
	is intended to make it easier to use Expat in small-memory
	devices. </li>

	<li> API revisions will be made to improve the runtime discoverability of
	Expat capabilities. </li>

	<li> Improve portability and performance. </li>

	<li> Substantially improve regression tests. </li>

	<li> Improve documentation. </li>

	<li> Full support for 64-bit platforms. (There are some known decoding
	problems currently.) </li>
	</ul>

	<p>When we're confident that the minor API changes are "right", we'll
	finallize the API and release Expat 2.0. Should additional functions
	be required as evolutionary improvements, the minor version number
	will be incremented, but all existing functions will be maintained for
	backward compatibility. Releases that are strictly bug fixes will
	have the same minor version number and will gain a "micro" version
	number (sometimes called a "patch level").</p>


	<h4>Far Future Activity</h4>

	<p>Once Expat 2.0 has been released, it will be maintained on a CVS
	branch. The head of CVS will be used to develop Expat 3.0. The
	changes in Expat 3.0 will be more substantial and will include
	important API changes. At this time, we're looking at the following
	changes:</p>

	<dl>
	<dt> More powerful event API </dt>
	<dd>
	<p>The new API will be sufficiently detailed that a complete and
	detailed DOM structure can be built, including both internal and
	external entity boundaries in parsed character data content,
	attribute value content, and entity values (such as found in
	internal entity declarations).</p>

	<p>This API will of necessity be somewhat more complex than the
	current API, but we expect the current API can be implemented on top
	of the new API. For users for whom the Expat 2.0 API is
	sufficiently powerful, this API will remain available.</p>
	</dd>

	<dt> Support for either pull or suspendable parsing </dt>
	<dd>
	<p>The new API will need to support some way to interrupt processing
	without having to parse all XML text passed to the parser so far.
	This can be done by either using a pull-based model or a push-based
	model (similar to the current API) with the added ability to suspend
	parsing on request.</p>

	<p>The specific API will depend on the model selected; either a
	pull-based model or an suspension model can support each other with
	little additional work, and the current push model can be built on
	top of either.</p>

	<p>The specific model and API will be discussed on the <a href=
	"http://mail.libexpat.org/mailman-21/listinfo/" >expat-discuss</a>
	mailing list.</p>
	</dt>

	<dt> New encoding support </dt>
	<dd>
	<p>A new library may be added to the Expat package that provides a
	flexible architecture for defining new encodings, and provides a
	large range of common encodings. (It should be possible to develop
	this so that it supports both Expat 2.0 and Expat 3.0.)</p>

	<p>Another approach which will be considered will be to support
	Expat's requirements for decoders using one of the existing open
	source encoding support libraries that meets Expat's requirements
	for portability. Possible technical approaches would include
	implementing an adapter, and developing such an external library to
	include direct support for the kind of interface support Expat
	needs.</p>
	</dd>

	<dt> <a href= "http://www.w3.org/TR/xml11/" >XML 1.1</a> (including <a
	href="http://www.w3.org/TR/xml-names11/" >Namespaces in XML
	1.1</a>), if it ever happens </dt>
	<dd>
	<p>Well, we're hoping, but it's not time to code for this yet.</p>
	</dd>
	</dl>

	<p>Additional goals may be added during the development of Expat 3.0;
	it's just too early to tell.</p>


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