Data integration systems

• TSIMMIS
  • Object Exchange Model (OEM): accessing heterogeneous information sources by translating source information into a common self-describing object model
  • mediator layer: translator (wrappers) queries over information in the common model (OEM) into requests the source can execute. The data returned by the source is converted back into the common model
  • template-based wrapper program handles a given set of queries
• Information manifold
  • Alon Y. Levy , Anand Rajaraman , Joann J. Ordille, "Querying heterogeneous information sources using source descriptions", Proceedings of the 22nd VLDB Conference, Bombay, India. 1996.
    • world view: a collection of virtual relations and classes
    • user poses queries according to the world view
    • source description in terms of contents and capabilities
    • query plans: query containment
• Tukwila
  • query multiple heterogeneous databases in uniform way
  • mediated schema
  • data sources mapped as views using mediated schema
  • query reformulation