WaterfallChartOLAPDataModel: Basic Requirements

The main responsibility of a WaterfallChartOLAPDataModel is to map data measures from an OLAP data structure to variable roles in a waterfall chart.

In your code, you can explicitly select measures in the OLAP data, or allow the component's OLAP data model to select measures by default.

A WaterfallChart's primary variable roles are

CategoryVariable

Specifies a classification variable whose values determine the number and arrangement of bars in the chart. A WaterfallChartOLAPDataModel maps this role to the first measure in the OLAP structure.

ResponseVariable

Specifies an analysis variable whose values determine the height of each bar. A WaterfallChartOLAPDataModel maps this role to the second measure in the OLAP structure.

To access OLAP data for a graph, you must know the name of the OLAP host server and connect to that server with a valid username and password. To use the OLAP data in a WaterfallChart, you must

• create an OLAPDataSet, either from the result set of a query that is executed on an OLAP provider or from the metadata that has been mapped to the OLAP data
• assign the OLAPDataSet to a WaterfallChartOLAPDataModel
• assign the WaterfallChartOLAPDataModel to a WaterfallChart.

The following code fragment generates a waterfall chart that plots actual sums against predicted sums for selected products, years, and countries.

// Create strings to store an SQL query, the OLAP server name,
// and the connection port.
   String OLAP_QUERY="SELECT "
                   + "{[PRODUCTLINE].[PRODUCT].MEMBERS} ON COLUMNS,"
                   + "CROSSJOIN({[TIME].[YEAR].MEMBERS},"
                   + "{[Measures].[ACTUAL_SUM],[Measures].[PREDICT_SUM]}) ON ROWS "
                   + "FROM MYOLAPCUBE";   // specify a valid OLAP data source
   String OLAP_SERVER="myOlapServer.com"; // use a valid server name
   int OLAP_PORT=8800;                    // use a valid port

// Create a WaterfallChartOLAPDataModel from an OLAPDataSet.
   WaterfallChartOLAPDataModel olapDataModel = null;
   try {
        // OLAPDataSet arguments: host, port, username, pwd, query
           olapDataModel=new WaterfallChartOLAPDataModel(
           new OLAPDataSet(OLAP_SERVER, OLAP_PORT, "myUsername", "myPwd",
                           OLAP_QUERY));
       } catch (Exception ex) { ex.printStackTrace(); }

// Create a WaterfallChart that uses the WaterfallChartOLAPDataModel as its data model
   WaterfallChart waterfallChart=new WaterfallChart();
   waterfallChart.setDataModel(olapDataModel);