This two-volume set LNCS 3290/3291 constitutes the refereed proceedings of the three confederated conferences CoopIS 2004, DOA 2004, and ODBASE 2004 held as OTM 2004 in Agia Napa, Cyprus in October 2004.

The 94 revised full papers presented were carefully reviewed and selected from a total of 380 submissions. In accordance with the three OTM 2004 main conferences CoopIS, DOA, and ODBASE, the papers are devoted to interoperability, workflow, and cooperation; distributed objects, infrastructure and enabling technology, and Internet computing; and data and Web semantics.