III. DATA DISCOVERY AND RETRIEVAL
In recent decades, different agencies have developed their
own geospatial catalogue systems to facilitate geospatial data
discovery. To enable users to find multi-discipline data across
different catalogues using single entry point instead of working
with each catalogue individually, GeOnAS implements the Catalogue
Federation. Previous proposed federation mechanisms,
especially query interface and query results assembling, are not
standard-based, and not very suitable for data discovery with
geospatial metadata models. GeOnAS adopts the OGC CSW
ebRIM profile [15] to provide a general and flexible way for
querying and access of distributed catalogue systems