An important concern in distributed hospital information systems is the integration of information across heterogeneous subsystems. Consistent data replication is a central problem to be solved in this domain. The specific requirements and problems for integration of information within hospitals are discussed and a middleware architecture which has been designed according to these requirements is presented.

Communication servers are often deployed in hospitals to connect heterogeneous subsystems. This paper discusses some problems with this approach and presents a federated schema-based middleware architecture as an alternative solution for propagation of information updates across heterogeneous subsystems within hospitals.