AMOS (Active Mediators Object System) is an architecture to model, locate, search, combine, update, and monitor data in information systems with many work stations connected using fast communication networks. The approach is called active mediators, since it introduces an intermediate level of ‘mediator’ software between data sources and their use in applications and by users, and since it supports ’active’ database facilities. A central part of AMOS is an Object-Oriented (OO) query with OO abstractions and declarative queries. The language is extensible to allow for easy integration with other systems. This allows for knowledge, now hidden within application programs as local data structures, to be extracted and stored in AMOS modules. A distributed AMOS architecture is being developed where several AMOS servers communicate, and where queries in a multi-database language are allowed to refer to several AMOS databases or other data sources. An overview is made of the architect...