Introduction

Cewolf can be used inside a Servlet/JSP based web application to embed complex graphical charts of all kinds (e.g. line, pie, bar chart, plots, etc.) into a web page. Therefore it provides a full featured tag library to define all properties of the chart (colors, strokes, legend, etc.). Thus the JSP which embedds the chart is not polluted with any java code. Everything is described with XML conform tags.

Cewolf is based on JFreeChart and uses it's rendering engine to render the final chart image into the clients response stream. No files are created on server side. Everything is based on lightweight session objects and dynamic data analysis. Cewolf consists of one servlet which handles the chart rendering and a taglibrary which translates the chart definition included in the JSP into an HTML img tag which consults the rendering servlet for retrieval of the appropriate chart.

Simce the project has been funded in the middle of 2002 there have been more then 150.000 page views and 16.000 downloads (Sourceforge activity max: >99,7%).

Fully free and open 100% Java compliant
  • LGPL license
  • no charges
  • no restrictions
  • Support on SourceForge Forums
  • short development and upgrade circles
  • no usage of native libraries
  • should run in every J2EE compliant server or servlet container
  • extensive usage of available open source projects
Full featured Chart Tag Library Huge number of different Charts
  • no java coding inside the JSP needed
  • XML description of a chart
  • design time validation of chart tags
  • extensive tag documentation
  • Line [XY]
  • [3D] Pie
  • [3D] Horizonal Bar
  • [3D] Vertical [XY] Bar
  • [3D] Stacked Vertical Bar
  • Area [XY]
  • Scatter Plot
  • Candlestick
  • High Low
  • Gantt
  • Meter
  • Overlaid
  • Combined

Example

You can simply define a chart by including a chart tag into your JSP like this: 

<cewolf:chart 
    id="XYChart"
    type="xy"
    title="XYChart" 
    <cewolf:gradient>
        <cewolf:point x="0" y="0" color="#FFFFFF"/>
        <cewolf:point x="0" y="300" color="#C8C8C8"/>
    </cewolf:gradient>
    <cewolf:data>
        <cewolf:producer id="xyData"/>
    </cewolf:data>
</cewolf:chart>
<cewolf:img chartid="XYChart" renderer="cewolf" width="400" height="300"/>

This results in a rendered chart like this:

examplechart

As you can see only the view is defined in the JSP page. The model is produced by a so called DataProducer which must be available in the pageContext of the JSP.

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