Using Parameters to Call Visualizations 
Due to the integration of SAP BusinessObjects Xcelsius and SAP NetWeaver BI, processes run during the runtime of BI data visualizations in the same way that they run during the runtime of BEx Web applications. These processes are automatically triggered in the background and can be overridden by specific Web Design API commands in BEx Explorer. Some of these processes are explained in the following variable parameterization example.
When visualization is started, the queries being used have to be instantiated. During runtime, the initial state of the queries is determined in the background. This is why the variables screen for Business Explorer runtime initially appears for mandatory variables in the queries being used. The query (and therefore also the website) does not start until the user has entered the mandatory variables. You can override this process and the associated query instantiation using a dynamic URL parameterization at runtime. You can do this with the Web Design API command SET_VARIALBES_STATE (set variable values).
More information: Set Variable Values, Dynamic Parameterization of Commands and Web Items