Distribution and Interoperability

An interoperable architecture allows users to query multiple and possibly remote image sources. Due to the autonomy of image repositories, each participating site needs to provide a wrapper; the wrapper is responsible for transforming MOQL (the common language) queries into local queries executable at the individual site. When the individual image source is using a database (relational or object-oriented) model, the transformation is simpler. However, translating content-based queries is not straightforward. When the image source is modeled as a file system or hyperlinks, the wrapper needs to provide search capabilities to support queries.

The interoperable architecture is designed on top of CORBA [Gro93]. CORBA provides transparencies at the platform and the communication levels. At the image database level different data models (different schemas) can be found, necessitating homogenization of the semantics of these schemas and any associated image content descriptions. The distributed architecture involves both homogeneous and heterogeneous systems. The participating sites should provide wrappers to transform MOQL queries into queries executable at the target sources for the heterogeneous case. The first distributed prototype is built for DISIMA sites only.