MCS - Metadata Catalog Service

MCS is a stand-alone metadata catalog service with an OGSA service interface. The metadata catalog associates application-specific descriptions with data files, tables, or objects. These descriptions, which are encoded in structured ways defined by "schema" or community standards, make it easier for users and applications to locate data relevant to specific problems.

For example, a data file containing a series of numbers could have associated metadata that reveals that the numbers are temperature readings, and further that those readings were taken at a particular field site. The metadata might also encode the fact that the numbers in the first column of each line are timestamps and the numbers in the second column are temperature readings measured in Kelvin units. A climate scientist who needs the temperature readings for that field station can search the metadata catalog and find the reference to this data file and the information about how to interpret the contents of the file.

MCS is integrated with OGSA-DAI, which provides metadata storage and basic Grid authentication mechanisms. When MCS is used with OGSA-DAI, Grid authentication is used to authorize accesses and manipulation of the metadata. MCS is frequently used in conjunction with the RLS component, which translates logical filenames into physical locations in specific storage systems.