Hi,

I have been using FOP to create PDF files for sometime now. Mostly as 
embedded code within my Struts Action classes, as mentioned in 
http://xml.apache.org/fop/embedding.html and it has been working just fine.

But this method requires the xml source to exist only as a java.io.File (if 
I am not mistaken), with no provision as an in memory object - like a Java 
String or Stream for example.

So when I looked at the Xalan site and this mailing list I saw the in 
memory implementation possible with the TransformerFactory and Transformer 
classes in Xalan. So, I tried this with a simple xml and xsl to test the 
concept first. But, I seem to be getting the error

building formatting object tree
building formatting object tree
javax.xml.transform.TransformerException
        at 
org.apache.xalan.transformer.TransformerImpl.transformNode(TransformerIm  
pl.java:1212)
        at 
org.apache.xalan.transformer.TransformerImpl.run(TransformerImpl.java:2894)
        at java.lang.Thread.run(Thread.java:484)
---------
java.lang.NullPointerException
        at 
org.apache.fop.fo.FOTreeBuilder.startDocument(FOTreeBuilder.java:167)
        at 
org.apache.xalan.transformer.QueuedStartDocument.flush(QueuedStartDocume  
nt.java:108)
        at 
org.apache.xalan.transformer.ResultTreeHandler.flushPending(ResultTreeHa  
ndler.java:758)
        at 
org.apache.xalan.transformer.ResultTreeHandler.startElement(ResultTreeHa  
ndler.java:245)
        at 
org.apache.xalan.transformer.ResultTreeHandler.startElement(ResultTreeHa  
ndler.java:209)
        at 
org.apache.xalan.templates.ElemLiteralResult.execute(ElemLiteralResult.j  
ava:704)
        at 
org.apache.xalan.transformer.TransformerImpl.executeChildTemplates(Trans  
formerImpl.java:2154)
        at 
org.apache.xalan.transformer.TransformerImpl.executeChildTemplates(Trans  
formerImpl.java:2097)
        at 
org.apache.xalan.transformer.TransformerImpl.applyTemplateToNode(Transfo  
rmerImpl.java:2029)
        at 
org.apache.xalan.transformer.TransformerImpl.transformNode(TransformerIm  
pl.java:1189)
        at 
org.apache.xalan.transformer.TransformerImpl.run(TransformerImpl.java:2894)
        at java.lang.Thread.run(Thread.java:484)
javax.xml.transform.TransformerException
        at 
org.apache.xalan.transformer.TransformerImpl.transformNode(TransformerIm  
pl.java:1212)
        at 
org.apache.xalan.transformer.TransformerImpl.run(TransformerImpl.java:2894)
        at java.lang.Thread.run(Thread.java:484)
---------
java.lang.NullPointerException
        at 
org.apache.fop.fo.FOTreeBuilder.startDocument(FOTreeBuilder.java:167)
        at 
org.apache.xalan.transformer.QueuedStartDocument.flush(QueuedStartDocume  
nt.java:108)
        at 
org.apache.xalan.transformer.ResultTreeHandler.flushPending(ResultTreeHa  
ndler.java:758)
        at 
org.apache.xalan.transformer.ResultTreeHandler.startElement(ResultTreeHa  
ndler.java:245)
        at org.apache.xalan.transformer.ResultTreeHandler.startElement(R  
esultTreeHandler.java:209)
        at 
org.apache.xalan.templates.ElemLiteralResult.execute(ElemLiteralResult.j  
ava:704)
        at 
org.apache.xalan.transformer.TransformerImpl.executeChildTemplates(Trans  
formerImpl.java:2154)
        at 
org.apache.xalan.transformer.TransformerImpl.executeChildTemplates(Trans  
formerImpl.java:2097)
        at 
org.apache.xalan.transformer.TransformerImpl.applyTemplateToNode(Transfo  
rmerImpl.java:2029)
        at 
org.apache.xalan.transformer.TransformerImpl.transformNode(TransformerIm  
pl.java:1189)
        at 
org.apache.xalan.transformer.TransformerImpl.run(TransformerImpl.java:2894)
        at java.lang.Thread.run(Thread.java:484)

I am using Fop-0.20.1 and the jars when compiling and running as below (on 
a win2000 platform)

C:\Fop-0.20.1>javac -classpath 
C:\Fop-0.20.1\lib\xalan-2.0.0.jar;C:\Fop-0.20.1\build\fop.jar TestXml.java
C:\Fop-0.20.1>java -classpath .;C:\Fop-0.20.1\lib\xalan-2.0.0.jar;C:\Fop  
-0.20.1\build\fop.jar;C:\Fop-0.20.1\lib\batik.jar;C:\Fop-0.20.1\lib\xerc  
es-1.2.3.jar TestXml

I have the bare minimum jar reqd for this test.

The xml and xsl are very simple and when used with FOP from the command 
line gives a PDF output with no problems. But the above error is thrown 
when used with the Java class TestXml

I was wondering if someone could help.

With the risk of making this mail even longer I will PASTE the Java code, 
XML and XSL as is in the mail so as to avoid attachments. So I apologize 
for the extremely long email :-)

JAVA code
----------------

import java.io.*;
import javax.xml.transform.*;
import javax.xml.transform.stream.*;
import javax.xml.transform.sax.*;

import org.apache.fop.apps.Driver;

public class TestXml {

    public static void main(String[] args) {

        try {

                // XML Will eventually be a Java String or Stream from another 
source.
                StreamSource xmlsource = new StreamSource(new 
FileReader("simple.xml"));

                Driver driver =new Driver();
                FileOutputStream fos = new FileOutputStream("simple.pdf");
                driver.setOutputStream(fos);            
                driver.setRenderer(Driver.RENDER_TXT);

                Transformer transformer = 
TransformerFactory.newInstance().newTransformer(new StreamSource(new 
FileReader("simple.xsl")));
                
                // Does not work
                transformer.transform(xmlsource,  new 
SAXResult(driver.getContentHandler()));
                
                //Works
                //transformer.transform(xmlsource,  new 
StreamResult(System.out));
                
    } catch (Exception e) {
            e.printStackTrace();
        }

    }
}


XML
--------

<?xml version="1.0"?>
<source>
    <books>
        <book year="2002">
                <name>XML Bible</name>
            <author>Elliot Rusty</author>
            <desc>A great book for XML beginners.</desc>
        </book>
        <book year="2002">
                <name>Thinking in Java</name>
            <author>Bruce Eckel</author>
            <desc>A great book for Java beginners.</desc>
        </book>
    </books>
</source>


XSL
----

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0" 
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"; 
xmlns:fo="http://www.w3.org/1999/XSL/Format";>
        <xsl:template match="/">
                <fo:root>
                        <fo:layout-master-set>
                                <fo:simple-page-master master-name="book-page" 
page-height="11in" 
page-width="8in" margin-top=".3in" margin-bottom=".5in" margin-left=".4in" 
margin-right=".2in">
                                        <fo:region-body margin-top="5.0in" 
margin-bottom=".5in"/>
                                        <fo:region-before extent="6in"/>
                                        <fo:region-after extent=".5in"/>
                                </fo:simple-page-master>
                        </fo:layout-master-set>
                        <xsl:apply-templates/>
                </fo:root>
        </xsl:template>


        <xsl:template match="source">
                <fo:page-sequence master-name="book-page">
                        <fo:static-content flow-name="xsl-region-before">
                                        <fo:block>
                                                Various sources for XML/Java
                                        </fo:block>
                        </fo:static-content>                    
                
                        <fo:flow flow-name="xsl-region-body">
                                        <fo:block font-size="7pt" 
text-indent=".5in">
                                                <xsl:apply-templates/>
                                        </fo:block>     
                                </fo:flow>
                        </fo:page-sequence>
        </xsl:template>
        
        <xsl:template match="books">
                <fo:block color="blue">
                        Books - <xsl:apply-templates/>
                </fo:block>
        </xsl:template>

        <xsl:template match="book">
                <fo:block color="green">
                        <xsl:apply-templates/>
                </fo:block>
        </xsl:template>

        <xsl:template match="name">
                <fo:block color="red">
                        <xsl:apply-templates/>
                </fo:block>
        </xsl:template>

        <xsl:template match="author">
                <fo:block color="orange">
                        <xsl:apply-templates/>
                </fo:block>
        </xsl:template>

        <xsl:template match="desc">
                <fo:block>
                        <xsl:apply-templates/>
                </fo:block>
        </xsl:template>

</xsl:stylesheet>


Thanks for the patience in reading this mail. Any help whatsoever will be 
highly appreciated.

Thanks,
Anil.







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