Metadata is usually defined as data about data. For a database, metadata is the databases' schema. the schema describes a view of the data held within the database. In a schema, these are the entities, the attributes and their types that make those entities and the relationships held between the entities.
Database metadata can also include such information as:
The RASH database RASHdb is a database of bioinformatics resource schema and the related metadata described above. The information stored in RASHdb can be used to answer the queries in the BioCompass.
RASHdb itself needs a schema that describes the elements within a database schema and the other information described above. So, if metadata is a model of the data in a database, then metadata that itself describes metadata is a metamodel. There are three levels to this metamodel:
RASHdb describes the elements of a database schema: Entities and their properties (attributes and relationships); the domain of attributes and the facets of relationships. It also describes the provenence of those elements -- where in the original resource that conceptualisation arose and where it is described in the documentation. The RASHdb schema also contains information on resource location, version, dates and creator of the schema.
The RASHdb metamodel is a schema represented in the information modelling language EXPRESS. This is an object flavoured language that can capture the elements of data representation in relational and object orientated databases, as well as those schema implicit in flat-file format databanks. It is the recommended representational form for the RASH process and use in the BioCompass. The RASHdb schema is itself represented in EXPRESS and automatically transformed to the data definition language statements to form the RASHdb. The schema has four principal components:
Having populated the RASHdb with schema and resource data, it can be used by the biocompass to answer resource queries and act as a guide to bioinformatics resources.