Catalogue Interoperability Protocol (CIP) - Release A Demonstrator System

Earth Observation catalogues and inventories are generally designed and operated on a ”mission-by-mission” basis. Often catalogues, inventories and associated user interfaces are generated from scratch and dedicated protocols are used to connect the user front-end (client) with the Earth Observation (EO) catalogue server. The result of this procedure is that Earth Observation catalogues are generally incompatible and the specific user interfaces only address the catalogue systems they are designed for.

However, enhanced user demands call for the interoperability of Earth Observation catalogues to enable cross-mission searches and multi-sensor product synergism. The critical and generic part of the Earth Observation catalogue technology which would allow such catalogue interoperability is the transmission/transaction protocol between the user client and the server.

The CIP defines the methods by which data retrieval, i.e. data location, requesting and delivery, shall be performed. In particular, it defines the processes and methods of interpretation of data requests or queries and interpretation of the results. It includes the definition of a data dictionary that specifies the common attributes that will be used to describe, in a standard manner, the primary objects within a catalogue system so as to promote interoperability between the catalogue systems provided by different agencies.

The Retrieval Manager supports the protocol and provides a software layer between:

• Client software which supports a user in the entering of searches, queries and orders for EO data;
• Dedicated server software accessing (existing) archives and inventory systems.

One of the key objectives of the CIP is to facilitate interoperability between catalogue systems. Catalogue interoperability can be defined as:

• Interoperability between the same types of service, e.g. inventory with inventory (the perception of all inventory systems as one single database, hiding the physical location of information);
  • Interoperability between different types of services, such as, guide, directory and inventory (the integration of high-level services).

This implies the integration of existing and future services so that they appear as a single domain. A further key factor in interoperability is the integration of catalogue systems from different agencies. This will eventually lead to all data being available to all users from a single access point of their choice, without having to first know what is available and where to go.

To achieve interoperability of catalogue systems, it is necessary to develop a common protocol that can be used by all agencies as the common denominator between separately developed catalogue systems. The use of the common protocol does not effect local agency developments or requirements, but it does provide a means for achieving interoperability with other systems.

The CIP specification is based upon the generic search and retrieval protocol standard Z39.50-1995. For the purpose of information retrieval in the Earth Observation domain a ”Z39.50 profile” has been specified which defines the parts of the full Z39.50 specification that are applicable for the CIP. This profile also defines the CIP specific information that shall be handled. This includes a ”set of attributes” for the Earth Observation domain that can be presented and searched, and a ”set of result elements” and retrieval formats.

The Retrieval Manager in the CIP A Demonstrator provides the following functions: it is the client's access point allows dynamical configuration of the client knows the location of the local or remote catalogues manages the collections owned (implementation of collection database/database management) decomposes and routes queries to local and remote catalogues manages and monitors queries collates results and returns them to client JOANNEUM RESEARCH developed as subcontractor to Logica/UK Z39.50 related components of the Retrieval Manager, especially the Explain subsystem. Further information: http://lcweb.loc.gov/z3950/agency/ profiles/cip.html