 | | | xinclude funnies | xinclude funnies 2003-08-23 - By Neil Pitman
I'll preface this with "I'm a bit new to digging around in Xerces and XInclude"
. (Xerces always worked, but then I wasn't using new, beta features.)
I'm trying to make Saxon 7.6.5 (XSLT) work with Xerces 2.5.0 (tarball not
recent cvs) using XInclude and SAX with my own XMLEntityResolvers
/EntityResolvers. Saxon has it's own issues but that's for another mailinglist.
Once upon a time, I would preprocess my files with Elliot Rusty Harold's
Xincluder from SourceForge into a separate XML. Now I'd like to stream it in
situ. (that means that the input files are understandable by elharo's
implementation so they are less suspect). The trick is to change the OS based
file references into arbitrary key references.
Here is what I understand. My questions follow.
Soon after hitting the include element, org.apache.xerces.xinclude
.XIncludeHandler.handleIncludeElement(XMLAttributes attributes) is called. He
creates a XMLResourceIdentifier with an explicit null public id and an explicit
null expanded system id (the literal system id is retrieved from the href and
represents a relative "file". This is what I used to use with XIncluder).
When he determines that there is, indeed, a resolver, he calls
EntityResolverWrapper holding my resolver. First the wrapper checks that the
public id and system id (the expanded one) are not null. They are so he exits
immediately.
I "fixed" this using XMLEntityManager.expandSystemId() to produce the expanded
system id in handleIncludeElement where the XMLResourceIdentifier is first
created.
Now with the EntityResolverWrapper getting a reasonable system id, my resolver
gets a reasonable id and it attempts to load the first xinclude. The system id
's are now a mixture of my keys and file bases. My entity resolver is
completely memory based so the file based URI's are confusing. For example:
In the old system running from the file system there were three files
file:///c:/work/proj/main.xml
file:///c:/work/proj/part1/subpart1/abc.xml
file:///c:/work/proj/part1/subpart1/helper.xml
With the elharo xincluder, main.xml had <xi:include href="part1/subpart1/abc
.xml"/> and abc.xml contained <xi:include href="methods.xml"/>. My Resolver
receives file:///c:/home/npitman/part1/subpart1/abc.xml. It gets the "file:///c
:/home/npitman/" part from the running location of the application.
XMLEntityManager noticed that the base system id of "main.xml" was null so he
assumed that he would need a real URI and that should be based on the current
working directory. In the memory-based situation, the hrefs are not so much
URI's as keys. I'm expecting just "part1/subpart1/abc.xml".
This is what I find in the literal system id. Unfortunately, this helps little
because the first include xincludes a second. This has an href of "helper.xml"
. In my key system, I'd expect to see "part1/subpart1/helper.xml".
Questions:
1) What is going on in org.apache.xerces.xinclude.XIncludeHandler
.handleIncludeElement? Setting the id's to null can't be right.
2) Is there a way to accept a blank base system id?
I'd like href="part1/subpart1/abc.xml" within "main.xml" to try to resolve
"part1/subpart1/abc.xml" and href="helper.xml" within "part1/subpart1/abc.xml"
to try to resolve "part1/subpart1/help.xml".
3) Alternately, is the there an extension mechanism, like the EntityResolver,
to externalize expandSystemId()?
I suppose that the fallback would be to set the base system id of main.xml to
an abitrary scheme like "npitman://" and the look up "npitman://part1/subpart1
/abc.xml" and "npitman://part1/subpart1/helper.xml"
Thanks for your patience in reading.
_________________________________________
Neil Pitman
neil.pitman@(protected)
+1.514.863.5465
ICQ#: 21101052
_________________________________________
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<DIV><FONT face=Arial size=2>I'll preface this with "I'm a bit new to digging
around in Xerces and XInclude". (Xerces always worked, but then I wasn't
using new, beta features.)</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I'm trying to make Saxon 7.6.5 (XSLT) work with
Xerces 2.5.0 (tarball not recent cvs) using XInclude and SAX with my
own XMLEntityResolvers/EntityResolvers. Saxon has it's own issues but
that's for another mailinglist. Once upon a time, I would preprocess my
files with Elliot Rusty Harold's Xincluder from SourceForge into a separate
XML. Now I'd like to stream it in situ. (that means that the input
files are understandable by elharo's implementation so they are less
suspect). The trick is to change the OS based file references into
arbitrary key references.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Here is what I understand. My questions
follow.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Soon after hitting the include element,
</FONT><FONT face=Arial
size=2>org.apache.xerces.xinclude.XIncludeHandler.</FONT><FONT face=Arial
size=2>handleIncludeElement(<FONT color=#0000ff size=2>XMLAttributes</FONT>
<FONT
size=2> attributes) is called. He creates a </FONT></FONT><FONT face
=Arial
size=2><FONT size=2><FONT size=2>XMLResourceIdentifier with an
explicit null public id and an explicit null expanded system id
(the literal system id is retrieved from the href and represents a
relative
"file". This is what I used to use with XIncluder).
</FONT></FONT></FONT><FONT face=Arial size=2><FONT size=2>When he determines
that there is, indeed, a resolver, he calls EntityResolverWrapper holding my
resolver. First the wrapper checks that the public id and system id (the
expanded one) are not null. They are so he exits
immediately.</FONT></FONT></DIV>
<DIV><FONT face=Arial size=2><FONT size=2></FONT></FONT> </DIV>
<DIV><FONT face=Arial size=2><FONT size=2>I "fixed" this using
XMLEntityManager.expandSystemId() to produce the expanded system id
in
handleIncludeElement where the <FONT size=2>XMLResourceIdentifier is first
created.</FONT></FONT></FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Now with the EntityResolverWrapper getting a
reasonable system id, my resolver gets a reasonable id and it attempts to
load the first xinclude. The system id's are now a mixture of my keys and
file bases. My entity resolver is completely memory based so the file
based URI's are confusing. For example:</FONT></DIV>
<DIV><FONT face=Arial size=2>In the old system running from the file system
there were three files</FONT></DIV>
<DIV><FONT face=Arial size=2><A
href="file:///c:/work/proj/main.xml">file:///c:/work/proj/main.xml</A></FONT><
/DIV>
<DIV><FONT face=Arial size=2>
<DIV><FONT face=Arial size=2><A
href="file:///c:/work/proj/part1/subpart1/abc.xml">file:///c:/work/proj/part1
/subpart1/abc.xml</A>
<DIV><FONT face=Arial size=2><A
href="file:///c:/work/proj/part1/subpart1/helper.xml">file:///c:/work/proj
/part1/subpart1/helper.xml</A></FONT></DIV></FONT></DIV></FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT size=2><FONT face=Arial>With the elharo xincluder, main.xml had
</FONT><FONT color=#0000ff size=1><FONT face=Arial color=#000000
size=2><</FONT></FONT><FONT face=Arial>xi:include
href="part1/subpart1/abc.xml<FONT color=#0000ff size=1><FONT color=#000000
size=2>"/> and abc.xml contained <xi:include href="methods.xml<FONT
color=#0000ff size=1><FONT color=#000000 size=2>"/>. My Resolver
receives <A
href="file:///c:/home/npitman/part1/subpart1/abc.xml">file:///c:/home/npitman/
<U><FONT
color=#0000ff>part1/subpart1/abc.xml</A></FONT></U></FONT></FONT></FONT></FONT>
</FONT></FONT><FONT
face=Arial size=2>. It gets the "<A
href="file:///c:/home/npitman/part1/subpart1/abc.xml">file:///c:/home/npitman/<
/A>"
part from the running location of the application. XMLEntityManager
noticed that the base system id of "main.xml" was null so he assumed that he
would need a real URI and that should be based on the current working
directory. In the memory-based situation, the hrefs are not so
much URI's as keys. I'm expecting just "part1/subpart1/abc.xml".
</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>This is what I find in the literal system id. 
;
Unfortunately, this helps little because the first include xincludes a
second. This has an href of "helper.xml". In my key system, I'd
expect to see "part1/subpart1/helper.xml".</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Questions:</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>1) What is going on in
org.apache.xerces.xinclude.XIncludeHandler.<FONT face=Arial
size=2>handleIncludeElement? Setting the id's to null can't be
right.</FONT></FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>2) Is there a way to accept a blank base system
id? </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I'd like href="part1/subpart1/abc.xml<FONT
color=#0000ff size=1><FONT color=#000000 size=2>" within "main.xml" to try to
resolve "part1/subpart1/abc.xml" and href="helper.xml" within
"part1/subpart1/abc.xml" to try to resolve "part1/subpart1/help.xml".
</FONT></FONT></FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>3) Alternately, is the there an extension
mechanism, like the EntityResolver, to externalize expandSystemId()?
</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2><FONT color=#0000ff size=1><FONT color=#000000
size=2>I suppose that the fallback would be to set the base system id of
main.xml to an abitrary scheme like "npitman://" and the look up
"npitman://part1/subpart1/abc.xml" and
"npitman://part1/subpart1/helper.xml"</FONT></FONT></FONT></DIV>
<DIV><FONT face=Arial size=2><FONT size=2><FONT
size=2></FONT></FONT></FONT> </DIV>
<DIV><FONT face=Arial size=2><FONT size=2><FONT size=2>Thanks for your patience
in reading.</DIV></FONT></FONT></FONT>
<DIV><FONT face=Arial size=2>_________________________________________<BR>Neil
Pitman<BR></FONT><A href="mailto:neil.pitman@(protected)"><FONT face=Arial
size=2>neil.pitman@(protected)</FONT></A><BR><FONT face=Arial
size=2>+1.514.863.5465<BR>ICQ#:
21101052<BR>_________________________________________<BR></FONT></DIV></BODY><
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