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From sh kh <>
Subject Trouble with Dynamic Chart
Date Thu, 06 Aug 2009 20:04:49 GMT
I'm following the Cocoon 2.2 tutorial.  I created a dynamic chart with
a java class implementing JFreeChart.  I want to view the rendered
chart in cocoon. I'm using flowscript and map:read, but no luck.  I get
a message saying the image contains errors when viewing src in Firefox
( I tested that the chart does show up fine if I write it to an
external file...I could link to this file but would prefer not to write the chart to the disk). 

I followed the approach from a previous post in the mailing list (

Here is the relevant method to return InputStream in MyClass

public MyClass {

public static InputStream getInputStream() {

(Code to create chart omitted...)

ByteArrayOutputStream out = new ByteArrayOutputStream(); 

JFreeChart chart = ChartFactory.createPieChart("Pie Chart", dataset, true, true, false);
ChartUtilities.writeChartAsPNG(out, chart, 500, 300); 
InputStream is = new ByteArrayInputStream(out.toByteArray());

return is;


function demo() {   
    var inputstream = MyClass.getInputStream();
        {"inputstream": inputstream});



    <map:match pattern="spring-bean">
        <map:call function="demo"/>

   <map:pipeline id="demo-internal" internal-only="true">
      <!-- This pipeline is invoked by the above flowscript. -->
      <map:match pattern="screens/spring-bean">

<!-- doesn't make a difference if I remove type="image" from map:read -->

      <map:read type="image" src="module:flow-attr:inputstream" mime-type="image/png"

Any hints will be appreciated.  Thanks.


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