Middleware 2004 : ACM IFIP USENIX International Middleware Conference Toronto Canada October 18 22 2004 ; proceedings This book constitutes the refereed proceedings of the ACM IFIP USENIX International Conference on Distributed Systems Platforms Middleware 2004 held in Toronto Canada in October 2004. The 25 revised full papers presented together with an invited paper were carefully reviewed and selected from a total of 194 submissions. The papers are organized in topical sections on peer to peer computing; routing protocols and overlay; middleware for replication and overlay; middleware for replication and transactions; publish subscribe systems; Web services: composition integration and interoperatibilty; middleware for mobility; application servers enterprise computing and software engineering