Problem using Java extensions

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Problem using Java extensions

Problem using Java extensions

2003-02-26 - By Karen Alexander

Reply: 1 2

I have a Java class that my customers can call from within their
stylesheets. However, I'm experiencing a problem where, occasionally, the
Java extension calls are calling the wrong methods in my class.

Here's an excerpt from a stylesheet that is making Java extension calls to
my class (DfXmlQuery):
<xsl:variable name="xdql"
select="java:com.documentum.xml.xdql.DfXmlQuery.new()"/>
<xsl:variable name="init" select="java:init($xdql)"/>
<xsl:variable name="param" select="java:setDql($xdql,$dql)"/>
<xsl:variable name="param3" select="java:includeContent($xdql,true())"/>
<xsl:variable name="param4" select="java:setErrorTag($xdql,$errorTag)"/>
<xsl:variable name="execute"
select="java:execute($xdql,'DF_READ_QUERY',$DMS_SESSION_ID)"/>

The template is instantiating my object and calling a number of methods on
it. However, occasionally the wrong method will be called. For example,
instead of the calling the 'execute' method, I will sometimes see that the
'setErrorTag' method is called (with the parameters that were given to the
'execute' method).

I have placed some tracing code into the org.apache.xalan.extensions package
to trace how the extension functions are being cached. The problem seems to
be related to having the wrong function returned from a cache.

In the trace output, it looks like we do a lookup to see if the method has
been cached. If not, it is added to the cache. However, at one point we do
a lookup for a method (e.g. 'execute') and the cache returns a different
method (e.g. 'setErrorTag').

Here is a snippet from my trace output where the method is not (yet) in the
cache:
>> org.apache.xalan.extensions.ExtensionsTable:extFunction
('http://xml.apache.org/xslt/java', 'setErrorTag', 'Vector@(protected)'
<mailto:'Vector@(protected)'> , 'Object@(protected)' <mailto:'Object@(protected)'> ,
'ExpressionContext@(protected)' <mailto:'ExpressionContext@(protected)'> )
>> org.apache.xalan.extensions.ExtensionHandlerJavaPackage:callFunction
('setErrorTag', 'Vector@(protected)' <mailto:'Vector@(protected)'> , 'Object@(protected)'
<mailto:'Object@(protected)'> , 'ExpressionContext@(protected)'
<mailto:'ExpressionContext@(protected)'> )
>> org.apache.xalan.extensions.ExtensionHandlerJavaPackage:getFromCache
('Object@(protected)' <mailto:'Object@(protected)'> , 'Object@(protected)'
<mailto:'Object@(protected)'> , 'Object[]@(protected)')
<< org.apache.xalan.extensions.ExtensionHandlerJavaPackage:getFromCache
--> null
>> org.apache.xalan.extensions.MethodResolver:getMethod ('Class@(protected)'
<mailto:'Class@(protected)'> , 'setErrorTag', 'Object[]@(protected)', 'Object[][]@(protected)',
'ExpressionContext@(protected)' <mailto:'ExpressionContext@(protected)'> , '2')
>> org.apache.xalan.extensions.MethodResolver:scoreMatch
('Class[]@(protected)', '0', 'Object[]@(protected)', '1000')
<< org.apache.xalan.extensions.MethodResolver:scoreMatch --> "1000"
>> org.apache.xalan.extensions.MethodResolver:convertParams
('Object[]@(protected)', 'Object[][]@(protected)', 'Class[]@(protected)', 'ExpressionContext@(protected)'
<mailto:'ExpressionContext@(protected)'> )
>> org.apache.xalan.extensions.MethodResolver:convert
('Object@(protected)' <mailto:'Object@(protected)'> , 'Class@(protected)'
<mailto:'Class@(protected)'> )
<< org.apache.xalan.extensions.MethodResolver:convert -->
"XDQLError"
<< org.apache.xalan.extensions.MethodResolver:getMethod --> "public void
com.documentum.xml.xdql.DfXmlQuery.setErrorTag(java.lang.String)"
>> org.apache.xalan.extensions.ExtensionHandlerJavaPackage:putToCache
('Object@(protected)' <mailto:'Object@(protected)'> , 'Object@(protected)'
<mailto:'Object@(protected)'> , 'Object[]@(protected)', 'Object@(protected)'
<mailto:'Object@(protected)'> )
putToCache->methodKey=617111046198565750
<< org.apache.xalan.extensions.ExtensionHandlerJavaPackage:putToCache
--> null
>> com.documentum.xml.xdql.DfXmlQuery:setErrorTag ('XDQLError')
<< org.apache.xalan.extensions.ExtensionHandlerJavaPackage:callFunction
--> null
<< org.apache.xalan.extensions.ExtensionsTable:extFunction --> null

In this snippet, the cache lookup for the 'execute' method returns
'setErrorTag':
>> org.apache.xalan.extensions.ExtensionsTable:extFunction
('http://xml.apache.org/xslt/java', 'execute', 'Vector@(protected)'
<mailto:'Vector@(protected)'> , 'Object@(protected)' <mailto:'Object@(protected)'> ,
'ExpressionContext@(protected)' <mailto:'ExpressionContext@(protected)'> )
>> org.apache.xalan.extensions.ExtensionHandlerJavaPackage:callFunction
('execute', 'Vector@(protected)' <mailto:'Vector@(protected)'> , 'Object@(protected)'
<mailto:'Object@(protected)'> , 'ExpressionContext@(protected)'
<mailto:'ExpressionContext@(protected)'> )
>> org.apache.xalan.extensions.ExtensionHandlerJavaPackage:getFromCache
('Object@(protected)' <mailto:'Object@(protected)'> , 'Object@(protected)'
<mailto:'Object@(protected)'> , 'Object[]@(protected)')
<< org.apache.xalan.extensions.ExtensionHandlerJavaPackage:getFromCache
--> "public void
com.documentum.xml.xdql.DfXmlQuery.setErrorTag(java.lang.String)"
>> org.apache.xalan.extensions.MethodResolver:convertParams
('Object[]@(protected)', 'Object[][]@(protected)', 'Class[]@(protected)', 'ExpressionContext@(protected)'
<mailto:'ExpressionContext@(protected)'> )

My customers are using Xalan 2.2.0, but I've had them try 2.4.1 and them
still see the problem.

I've been searching through the bug database and bug 14236
(http://nagoya.apache.org/bugzilla/show_bug.cgi?id=14236
<http://nagoya.apache.org/bugzilla/show_bug.cgi?id=14236> ) looks somewhat
similar to my issue. Can you tell me if the fix is in the 2.4.1 release?

I'm guessing that the fix isn't in 2.4.1, so I'm trying to build the code
from CVS. However, I'm having some problems because I have to make sure
that the code is compatible with Java 1.1.8. Are the jar files available
for the nightly builds?

Thanks for your help,
- Karen

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=utf-8">
<TITLE>Message</TITLE>

<META content="MSHTML 6.00.2600.0" name=GENERATOR></HEAD>
<BODY>
<DIV><SPAN class=000024406-26022003><FONT face="Comic Sans MS" size=2>I have a
Java class that my customers can call from within their stylesheets. 
However, </FONT></SPAN><SPAN class=000024406-26022003><FONT face="Comic Sans MS
"
size=2>I'm experiencing a problem where, occasionally, the Java extension calls
are calling the wrong methods in my class.</FONT></SPAN></DIV>
<DIV><SPAN class=000024406-26022003><FONT face="Comic Sans MS"
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=000024406-26022003><FONT face="Comic Sans MS" size=2>Here's an
excerpt from a stylesheet that is making Java extension calls to my class
(DfXmlQuery):</FONT></SPAN></DIV>
<DIV><SPAN class=000024406-26022003><FONT face="Comic Sans MS" size=2><FONT
face="Courier New"><xsl:variable name="xdql"
select="java:com.documentum.xml.xdql.DfXmlQuery.new()"/><BR><xsl:variable
name="init" select="java:init($xdql)"/><BR><xsl:variable name="param"
select="java:setDql($xdql,$dql)"/><BR><xsl:variable name="param3"
select="java:includeContent($xdql,true())"/><BR><xsl:variable
name="param4" select="java:setErrorTag($xdql,$errorTag)"/><BR></FONT><FONT
face="Courier New"><xsl:variable name="execute"
select="java:execute($xdql,'DF_READ_QUERY',$DMS_SESSION_ID)"/><BR></FONT><
/FONT></SPAN></DIV>
<DIV><SPAN class=000024406-26022003><FONT face="Comic Sans MS" size=2>The
template is instantiating my object and calling a number of methods on it.&nbsp
;
However, occasionally the wrong method will be called.  For example,
instead of the calling the 'execute' method, I will sometimes see that the
'setErrorTag' method is called (with the parameters that were given to the
'execute' method).</FONT></SPAN></DIV>
<DIV><SPAN class=000024406-26022003><FONT face="Comic Sans MS"
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=000024406-26022003><FONT face="Comic Sans MS" size=2>I have
placed some tracing code into the org.apache.xalan.extensions package to trace
how the extension functions are being cached.  The problem seems to be
related to having the wrong function returned from a cache. 
</FONT></SPAN></DIV>
<DIV><SPAN class=000024406-26022003><FONT face="Comic Sans MS"
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=000024406-26022003><FONT face="Comic Sans MS" size=2>In the
trace output, it looks like we do a lookup to see if the method has been
cached.  If not, it is added to the cache.  However, at one point we
do a lookup for a method (e.g. 'execute') and the cache returns a different
method (e.g. 'setErrorTag').</FONT></SPAN></DIV>
<DIV><SPAN class=000024406-26022003><FONT face="Comic Sans MS"
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=000024406-26022003><FONT face="Comic Sans MS" size=2>Here is a
snippet from my trace output where the method is not (yet) in the
cache:</FONT></SPAN></DIV>
<DIV><SPAN class=000024406-26022003><FONT face="Comic Sans MS" size=2><FONT
face="Courier New" size=1>>>
org.apache.xalan.extensions.ExtensionsTable:extFunction
('http://xml.apache.org/xslt/java', 'setErrorTag', <A
href="mailto:'Vector@(protected)'">'Vector@(protected)'</A>, <A
href="mailto:'Object@(protected)'">'Object@(protected)'</A>, <A
href="mailto:'ExpressionContext@(protected)'">'ExpressionContext@(protected)'</A>)<BR> 
>> org.apache.xalan.extensions.ExtensionHandlerJavaPackage:callFunction
('setErrorTag', <A href="mailto:'Vector@(protected)'">'Vector@(protected)'</A>, <A
href="mailto:'Object@(protected)'">'Object@(protected)'</A>, <A
href="mailto:'ExpressionContext@(protected)'">'ExpressionContext@(protected)'</A>)<BR> 
  
>> org.apache.xalan.extensions.ExtensionHandlerJavaPackage:getFromCache
(<A href="mailto:'Object@(protected)'">'Object@(protected)'</A>, <A
href="mailto:'Object@(protected)'">'Object@(protected)'</A>,
'Object[]@(protected)')<BR>    <<
org.apache.xalan.extensions.ExtensionHandlerJavaPackage:getFromCache -->
null<BR>    >>
org.apache.xalan.extensions.MethodResolver:getMethod (<A
href="mailto:'Class@(protected)'">'Class@(protected)'</A>, 'setErrorTag', 'Object[]@(protected)',
'Object[][]@(protected)', <A
href="mailto:'ExpressionContext@(protected)'">'ExpressionContext@(protected)'</A>,
'2')<BR>      >>
org.apache.xalan.extensions.MethodResolver:scoreMatch ('Class[]@(protected)', '0',
'Object[]@(protected)', '1000')<BR>      <<
org.apache.xalan.extensions.MethodResolver:scoreMatch -->
"1000"<BR>      >>
org.apache.xalan.extensions.MethodResolver:convertParams ('Object[]@(protected)',
'Object[][]@(protected)', 'Class[]@(protected)', <A
href="mailto:'ExpressionContext@(protected)'">'ExpressionContext@(protected)'</A>)<BR> 
      
>> org.apache.xalan.extensions.MethodResolver:convert (<A
href="mailto:'Object@(protected)'">'Object@(protected)'</A>, <A
href="mailto:'Class@(protected)'">'Class@(protected)'</A>)<BR>     
  
<< org.apache.xalan.extensions.MethodResolver:convert -->
"XDQLError"<BR>    <<
org.apache.xalan.extensions.MethodResolver:getMethod --> "public void
com.documentum.xml.xdql.DfXmlQuery.setErrorTag(java.lang.String)"<BR> 
  
>> org.apache.xalan.extensions.ExtensionHandlerJavaPackage:putToCache (<A
href="mailto:'Object@(protected)'">'Object@(protected)'</A>, <A
href="mailto:'Object@(protected)'">'Object@(protected)'</A>, 'Object[]@(protected)', <A
href="mailto:'Object@(protected)'">'Object@(protected)'</A>)<BR>putToCache-&gt
;methodKey=617111046198565750<BR>   
<< org.apache.xalan.extensions.ExtensionHandlerJavaPackage:putToCache
--> null<BR>    >>
com.documentum.xml.xdql.DfXmlQuery:setErrorTag ('XDQLError')<BR>  <<
org.apache.xalan.extensions.ExtensionHandlerJavaPackage:callFunction -->
null<BR><< org.apache.xalan.extensions.ExtensionsTable:extFunction -->
null</FONT></FONT></SPAN></DIV>
<DIV><SPAN class=000024406-26022003><FONT face="Comic Sans MS"
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=000024406-26022003><FONT face="Comic Sans MS" size=2><FONT
face="Courier New" size=1><FONT face="Comic Sans MS" size=2></FONT> </DIV>
<DIV><SPAN class=000024406-26022003></SPAN><FONT face="Comic Sans MS"><FONT
size=2>I<SPAN class=000024406-26022003>n this snippet, the cache lookup for the
'execute' method returns 'setErrorTag':</SPAN></FONT></FONT><BR>>>
org.apache.xalan.extensions.ExtensionsTable:extFunction
('http://xml.apache.org/xslt/java', 'execute', <A
href="mailto:'Vector@(protected)'">'Vector@(protected)'</A>, <A
href="mailto:'Object@(protected)'">'Object@(protected)'</A>, <A
href="mailto:'ExpressionContext@(protected)'">'ExpressionContext@(protected)'</A>)<BR> 
>> org.apache.xalan.extensions.ExtensionHandlerJavaPackage:callFunction
('execute', <A href="mailto:'Vector@(protected)'">'Vector@(protected)'</A>, <A
href="mailto:'Object@(protected)'">'Object@(protected)'</A>, <A
href="mailto:'ExpressionContext@(protected)'">'ExpressionContext@(protected)'</A>)<BR> 
  
>> org.apache.xalan.extensions.ExtensionHandlerJavaPackage:getFromCache
(<A href="mailto:'Object@(protected)'">'Object@(protected)'</A>, <A
href="mailto:'Object@(protected)'">'Object@(protected)'</A>,
'Object[]@(protected)')<BR>    <<
org.apache.xalan.extensions.ExtensionHandlerJavaPackage:getFromCache -->
"public void
com.documentum.xml.xdql.DfXmlQuery.setErrorTag(java.lang.String)"<BR> 
  
>> org.apache.xalan.extensions.MethodResolver:convertParams
('Object[]@(protected)', 'Object[][]@(protected)', 'Class[]@(protected)', <A
href="mailto:'ExpressionContext@(protected)'">'ExpressionContext@(protected)'</A>)<BR></DIV><
/FONT><FONT
face="Courier New" size=1></FONT>
<DIV> </DIV>
<DIV><SPAN class=000024406-26022003>My customers are using Xalan 2.2.0, but I
've
had them try 2.4.1 and them still see the problem. </SPAN></DIV>
<DIV><SPAN class=000024406-26022003></SPAN> </DIV>
<DIV><SPAN class=000024406-26022003>I've been searching through the bug
database
and bug 14236 (<A
href="http://nagoya.apache.org/bugzilla/show_bug.cgi?id=14236">http://nagoya
.apache.org/bugzilla/show_bug.cgi?id=14236</A>)
looks somewhat similar to my issue.  Can you tell me if the fix is in the
2.4.1 release?  </SPAN></DIV>
<DIV><SPAN class=000024406-26022003></SPAN> </DIV>
<DIV><SPAN class=000024406-26022003></SPAN><SPAN class=000024406-26022003>I'm
guessing that the fix isn't in 2.4.1, so I'm trying to build the code from
CVS.  However, I'm having some problems because I have to make sure that
the code is compatible with Java 1.1.8.  Are the jar files available for
the nightly builds?</SPAN></DIV></FONT></SPAN>
<DIV><FONT face="Comic Sans MS" size=2></FONT> </DIV>
<DIV><FONT face="Comic Sans MS" size=2><SPAN class=000024406-26022003>Thanks
for
your help,</SPAN></FONT></DIV>
<DIV><FONT face="Comic Sans MS" size=2><SPAN
class=000024406-26022003></SPAN></FONT><FONT face="Comic Sans MS" size=2> 
-
Karen</FONT> </DIV>
<DIV> </DIV></BODY></HTML>