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In this article, the Pentaho ChartBeans project is introduced. Pentaho ChartBeans is a wrapper around other chart engines (such as JFreeChart and Open Flash Chart). Wrapping these "chart engines" creates a single way of expressing charts.

History

Several designs were considered for Pentaho ChartBeans. The first design was based on JavaBeans and is the source from which the term "beans" derives. The proposal was for two layers of beans--one at the chart component level and one at the chart type level. At the lower level, beans would represent parts of the chart: the plot, axes, series, and titles. The higher level beans would put the pieces together to form chart types of interest to users, such as a BarChartBean, LineChartBean, and PieChartBean.

The second design was based on a Document Object Model (DOM). A chart DOM is an object model that consists of elements which can have attributes and child elements. Elements have an associated namespace. The argument against the use of JavaBeans is that there are no namespaces.

In addition to the JavaBeans vs. DOM decision, it was important that the starting point for a chart be its data. The data are chart type-agnostic.

Finally, it was decided that even the chart type should be a styling issue--not a structural issue. This is because the same series could be used for multiple chart types.

Prerequisites

Charting Terminology

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