Using data object data in a report
A data object provides a report access to predesigned data sources, data sets, data models, and cubes. Report developers create data objects to streamline the report creation process. Data objects provide the following benefits:
*Simplified data access and retrieval. The predesigned data sources, data sets, data models, and cubes in a data object enable report developers to select the data to use in a report without knowledge of the underlying data source, how to connect to it, and how to extract data from it.
*Reusability across multiple reports. If a suite of reports require the same data, designing the data sources, data sets, data models, and cubes once in a shared data object eliminates the need to design the same elements repeatedly for each report.
*Dynamic updates to data items. Changes to data items in a data object propagate to reports that use the data object, ensuring that reports have the latest updates, such as connection properties.
A report accesses data from a data object through either a data object design (.datadesign) file or a data object store (.data). The data design file retrieves data, on demand, each time the report is run. A data object store contains cached, or materialized, data, and provides much more efficient access to data. If getting real-time data is more important than report generation speed, use the data object design file. If data in the underlying data source does not change constantly, or if a data object store is generated regularly, use the data object store.
As with other types of data sources, for a report to use data from a data object, you must create the following BIRT objects:
*A data source that contains the information to connect to a data object
*A data set that specifies the data to use from a data set, data model, or cube in the data object