The features of a database system specifically designed to support evolution are presented. The design of the F2 system has been deliberately directed toward integration of evolution features and the flexibility of structures at every level. This has leaded to an architecture where the meta-circular organization of the objects management is not an aesthetic facet but a concrete property of the system.
Many applications require the capability to define and manipulate a collection of related objects as a single unit. Object-oriented database models and systems usually provide the concept of composite object for that purpose. The concept of context that we propose here provides another, more general, way to view and manipulate collections of objects. We compare the two concepts both in their formal definitions and in their implementation in object-oriented database system.
We propose a DBMS the data model of which is an extension of the Entity-Relationship model of Chen. The main extensions include the specialization and generalization concepts of Smith & Smith and the possibility to define relationships between relationships. In addition we extend the concept of a role in a relationship, to a multi-valued role which enables to associate a set of tuples performing the same function in a relationship. A query language has been designed in order to deal with the enhanced semantic capabilities of the data model supported by the ECRINS/86 system.
We introduce a model for information systems specification which covers the spaces of data, semantic contexts, events, objects life-cycle, integrity constraints, and operating periods. For each one of these space we define a structure and its interpretation that allow to specify this particular aspect of the system. In this approach data and event structures are independent. It is the object life-cycle structure that binds processes to objects on which they operate. Semantic contexts make process and integrity constraints independent from the details of the data structure. The definition of operating period determine which integrity constraints are active and which processes are allowed to execute at a given time. When put together, these specifications form a global information system specification that can be checked for consistency and completeness and that can be used to predict global system's behavior.
Features specially devoted to schema evolution in the F2 object-oriented database system are presented in this paper. They include a meta-circular and reflective model where primitive operations (create, update, delete) on schema objects form a complete taxonomy of schema changes. All the schema objects of a database are updatable and the consequences of these changes on objects are handled either by the trigger mechanism or by the automatic enforcement of the model invariants. The non-traditional physical storage of objects is particularly well suited to efficiently support schema changes.
Most of the efforts concerninggraphical representations ofhumans (Virtual Humans) have beenfocused on synthesizing geometryfor static or animated shapes. Thenext step is to consider a human bodynot only as a 3D shape, but as anactive semantic entity with features,functionalities, interaction skills,etc. We are currently working on anontology-based approach to makeVirtual Humans more active andunderstandable both for humans andmachines. The ontology for VirtualHumans we are defining will providethe “semantic layer” required toreconstruct, stock, retrieve, reuse andshare content and knowledge relatedto Virtual Humans.
Expressive facial animation synthesis of human like characters has had many approacheswith good results. MPEG-4 standard has functioned as the basis of many of thoseapproaches. In this paper we would like to lay out the knowledge of some of thoseapproaches inside an ontology in order to support the modeling of emotionalfacial animation in virtual humans (VH). Inside this ontology we will present MPEG-4facial animation concepts and its relationship with emotion through expression profilesthat utilize psychological models of emotions. The ontology allows storing, indexing andretrieving prerecorded synthetic facial animations that can express a given emotion. Alsothis ontology can be used a refined knowledge base in regards to the emotional facialanimation creation. This ontology is made using Web Ontology Language and the resultsare presented as answered queries.
