[Expat-checkins] htdocs/dev roadmap.html,NONE,1.1

Wed, 04 Sep 2002 08:47:42 -0700

Update of /cvsroot/expat/htdocs/dev
In directory usw-pr-cvs1:/tmp/cvs-serv26996

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	roadmap.html 
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Add HTML version of the roadmap document currently in development.

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        <td class="banner"><h2>Expat Development Roadmap</h2></td>
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<h2>PROPOSAL</h2>

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.

<h3>Goals</h3>

We do not plan to alter the goals of the Expat
project. We intend to continue to develop Expat to have the following
qualities:

<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>

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.

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>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>

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.

<h4>Near Future Activity</h4>

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:

<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>

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").

<h4>Far Future Activity</h4>

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:

<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 and
  attribute value content.</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.
</dd>

<dt> New encoding support </dt>
<dd>
 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.)

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.
</dd>

<dt> XML 1.1, 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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