The data engine contains the APIs and provides services to retrieve and transform data. The data services retrieve data from its source and process the data as specified by the report design. When used by the generation engine, the data services retrieve data from the data source specified in the design. When used by the presentation engine, the data services retrieve data from the report document. The data engine extension of ODA provides the connection method and the drivers for data sources.

The data engine provides two key service types: data access services and data transformation services. The data access services communicate with the ODA framework to retrieve data. The data transformation services perform such operations as sorting, grouping, aggregating, and filtering the data returned by the data access services.

BIRT uses the ODA framework provided by the Eclipse Data Tools Platform project to manage ODA and native drivers, load drivers, open connections, and manage data requests. The ODA framework contains extension points that support adding a custom ODA driver. Write a custom ODA driver if you have a data source that BIRT does not support and a scripted data source is not desired. Use of a custom ODA driver may require extending not only the data engine but also BIRT Report Designer. A BIRT Report Designer extension is necessary if the data source requires a user interface component to specify the data set and data source properties.