Typically the Data Contents XML files are hand crafted by a developer. However the infrastructure provides Ant targets to create a Data Contents XML file from the database. The Data Extractor is invoked by executing a build command of build extractdata. By default the full database is extracted and DMX files are created for any tables that contain data. An optional parameter of tablename can be passed to specify that only one or more tables should be extracted e.g. build extractdata -Dtablename=Users. If you want to extract multiple tables during the one run, pass a comma separated list of tables to the tablename parameter.
The generated .DMX files are placed in a %SERVER_DIR%/build/dataextractor folder. Under this folder the contents of any clobs or blobs are also extracted and stored in a file which is based on the naming format: <tablename><rownumber>.