Using a scripted data source
Creating a scripted data source and a non-scripted data source are similar tasks. The differences between creating a scripted data source and a non‑scripted data source are:
*The scripted data source must be selected from the list of data source types when creating a scripted data source.
*Two event handler methods, open( ) and close( ), are available only for a scripted data source.
Every scripted data source must have at least one scripted data set. The differences between creating a scripted data set and a non-scripted data set are:
*The scripted data set must be associated with a scripted data source.
*The code for the scripted data set fetch( ) event handler method must be provided.
*There is a different dialog for identifying the columns of a scripted data set.
When using BIRT Report Designer to create a scripted data source, the following tasks must be performed:
*Create a scripted data source.
Right-click on Data Sources in Data Explorer and select Scripted Data Source in the list of data source types.
*Create a scripted data set.
Right-click on Data Sets in Data Explorer and select a scripted data source from the list of available data sources.
*Define output columns.
Define the names and types of output columns, using the scripted data set editor.
*Supply code for the data source open( ) and close( ) methods.
There are two scripted data source event handler methods, open( ) and close( ). It is not mandatory to implement either method, but most applications require the use of the open( ) method to initialize a data source. Typically, you create a Java object for accessing the data source in the open( ) method.
Use the close( ) method to clean up any loose ends, including setting object references to null to ensure that the objects are deleted during garbage collection.
*Supply code for the data set methods.
There are three scripted data set event handler methods, open( ), fetch( ), and close( ). Implementing the fetch( ) method is mandatory to initialize variables and to prepare the data source for fetching data.
Use the fetch( ) method to get a row of data from the data source and to populate the columns of the row object. The fetch( ) method must return either true or false. A true value tells BIRT that there is another row to process. A false return value signifies that there are no more rows to process.
Use the close( ) method to perform clean‑up operations.
*Place the columns on the report layout.
Place a data set column on a report layout the same way you place a column for a non-scripted data set.
The following tutorial guides you through the procedure required to perform each task in this process.