New applications such as CAD, AI, and hypermedia require direct representation and flexible use of complex objects, behavioral knowledge, and multimedia data. To this end, we have devised a knowledge base management system called Jasmine. An object-oriented approach in a programming language also seems promising for use in Jasmine. Jasmine extends the current object-oriented approach and provides the following features. Our object model is based on functional data models and well-established set theory. Attributes or functions composing objects can represent both structural and behavioral knowledge. The object model can represent incomplete and generic knowledge. The model can support the basic storage and operations of multimedia data. The facets of attributes can flexibly represent constraints and triggers. The object manipulation language can support associative access of objects. The structural and behavioral knowledge can be uniformly treated to allow the user to specify complex object operations in a compact manner. The user-defined and system-defined attributes can be uniformly specified to ease user customization of the language. The classes and instances can be uniformly accessed. Incomplete knowledge can be flexibly accessed. The system has a layered architecture. Objects are stored in nested relations provided by extensive DBMS as a sublayer. User query of objects is compiled into relational operations such as select and join, which can be efficiently processed using hashing. The behavioral knowledge is compiled into predicate and manipulation function interfaces that can directly access tuples in a buffer.— Authors' Abstract