Methods and apparatus, including computer program products, for processing data objects having data items. The method includes classifying each data object into a write-enabled object or a read-only object, storing write-enabled data objects in a database, and archiving read-only data objects. The archiving includes converting the data objects to markup objects, wherein each markup object represents the data items of the corresponding data object, concatenating the markup objects to a single data structure that is byte addressable, and indexing object identification for each markup object to addresses of the data structure.