Xalan C++ changes coming

[Da...@lotus.com]

I want to let everyone know that we are preparing to check in some major
changes to the Xalan C++ code base.  These changes should appear early next
week.

We are planning for Xalan C++ to move to an abstract DOM and since there is
no standard set of C++ abstract base classes, we are defining our own.
These will mirror the W3C's IDL definitions, but will be qualified with the
Xalan name, to avoid collisions.  (If, and when, the C++ community agrees
on a set of base classes, we will migrate to those.).

Reasons for doing this include:

   1. By using a set of abstract base classes, other DOMs can be used with
   Xalan.  For example, someone might write a "virtual" DOM that is not
   parsed from XML into a tree structure, but behaves like it was.

   2. We hope to create a high-performance, read-only input DOM for Xalan
   C++, similar to Xalan J's DTM.  We will tailor this DOM for XSLT, which
   should give us a serious performance boost.

   3. Our internal stylesheet classes will also derive from this DOM,
   making it easier for people to write stylesheet tooling interfaces.
   Currently, we derive these classes from  Xerces' internal implementation
   classes.

   4. There has been a lot of interest in COM interfaces for Xerces and
   Xalan.  Using a set of abstract classes will make it much easier to
   write COM interfaces for Xalan C++.

However, I do need to make it clear that these interfaces are experimental,
and are subject to change.  We hope that, at some point, we can migrate to
a standard set of C++ abstract base classes for the DOM.

I also want to give another pitch to recruit contributions to Xalan C++.
We have a lot of interesting things that need to be done, and it would be
great to bring in more people.

Dave

RE: Xalan C++ changes coming

[Sean Forde <sf...@lizardtech.com>]

I was assuming that Xalan would use the Xerces set of DOM classes, no? Does
this mean that XML which I have parsed into a Xerces DOM tree has to be
serialized and then reparsed by Xalan?

	-Sean Forde

>   -----Original Message-----
>   From: David_N_Bertoni@lotus.com [mailto:David_N_Bertoni@lotus.com]
>   Sent: Friday, March 31, 2000 12:03 PM
>   To: xalan-dev@xml.apache.org
>   Subject: Xalan C++ changes coming
>
>
>   I want to let everyone know that we are preparing to check in some major
>   changes to the Xalan C++ code base.  These changes should
>   appear early next
>   week.
>
>   We are planning for Xalan C++ to move to an abstract DOM and
>   since there is
>   no standard set of C++ abstract base classes, we are defining our own.
>   These will mirror the W3C's IDL definitions, but will be
>   qualified with the
>   Xalan name, to avoid collisions.  (If, and when, the C++
>   community agrees
>   on a set of base classes, we will migrate to those.).
>
>   Reasons for doing this include:
>
>      1. By using a set of abstract base classes, other DOMs can
>   be used with
>      Xalan.  For example, someone might write a "virtual" DOM that is not
>      parsed from XML into a tree structure, but behaves like it was.
>
>      2. We hope to create a high-performance, read-only input DOM
>   for Xalan
>      C++, similar to Xalan J's DTM.  We will tailor this DOM for
>   XSLT, which
>      should give us a serious performance boost.
>
>      3. Our internal stylesheet classes will also derive from this DOM,
>      making it easier for people to write stylesheet tooling interfaces.
>      Currently, we derive these classes from  Xerces' internal
>   implementation
>      classes.
>
>      4. There has been a lot of interest in COM interfaces for Xerces and
>      Xalan.  Using a set of abstract classes will make it much easier to
>      write COM interfaces for Xalan C++.
>
>   However, I do need to make it clear that these interfaces are
>   experimental,
>   and are subject to change.  We hope that, at some point, we can
>   migrate to
>   a standard set of C++ abstract base classes for the DOM.
>
>   I also want to give another pitch to recruit contributions to Xalan C++.
>   We have a lot of interesting things that need to be done, and
>   it would be
>   great to bring in more people.
>
>   Dave
>