OGC Web Coverage Service Overview
The General Catalog Interface Model provides a set of abstract service interfaces that support the discovery, access, maintenance and organization of catalogs of geospatial
information and related resources. The interfaces specified are intended to allow users or application software to find information that exists in multiple distributed computing
environments, including the World Wide Web WWW environment. All behavior requiring sessions is expressed by a dynamic model of conversation state and state
transitions. The model expresses the states and messages that trigger the changes in state.
An Application Profile is predicated on the existence of one protocol binding in the base specification. In the case of the Catalog Services Specification, a profile could reference
CORBA, Z39.50, or HTTP protocol bindings. In most, but not all, protocol bindings, there may be restrictions or refinements on implementation of the General Model agreed
within an implementation community.
Figure 7 - Catalog Reference Model Architecture, shows the Reference Architecture assumed for development of the OGC Catalog Interface. The architecture is a multi-tier
arrangement of clients and servers. To provide a context, the architecture shows more than just catalog interfaces. The bold lines illustrate the scope of OGC Catalog and
Features interfaces.
The Application Client shown in Figure 7 - Catalog Reference Model Architecture interfaces with the Catalog Service using the OGC Catalog Interface. The Catalog
Service may draw on one of three sources to respond to the Catalog Service request: a Metadata Repository local to the Catalog Service, a Resource service, or another Catalog
Service. The interface to the local Metadata Repository is internal to the Catalog Service. The interface to the Resource service can be a private or OGC Interface. The interface
between Catalog Services is the OGC Catalog Interface. In this case, a Catalog Service is acting as both a client and server. Data returned from an OGC Catalog Service query is
processed by the requesting Catalog Service to return the data appropriate to the original Catalog request.
describes OGC Interfaces
Applicatio Application
Applicatio Server
Catalog Service
Metadata local
Metadata Data
Data OGC Catalog
Interface
Private Interfaces
Repository Client
Federated Search
Figure 7 - Catalog Reference Model Architecture
Resources in a catalog are discovered using a filter. Queries can be temporally constrained using the standard scalar operators found in the Filter specification
PropertyIsBetween, PropertyIsEqualTo, etc .... However, the Filter specification does
Copyright © 2007 Open Geospatial Consortium, Inc. All Rights Reserved.
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not formally define temporal operators at the time; the operators like Inside, Overlaps, etc could be applied to temporal data to achieve this task.
Here is an example of a temporal query finding records modified between two specific dates that uses scalar operators to constrain the modified property:
GetRecords xmlns=http:www.opengis.netcatcsw
xmlns:rim=urn:oasis:names:tc:ebxml-regrep:rim:xsd:2.5 xmlns:ogc=http:www.opengis.netogc
outputFormat=textxml; charset=UTF-8 Query typeNames=rim:ExtrinsicObject
Constraint ogc:Filter
ogc:PropertyIsBetween ogc:PropertyNamerim:ExtrinsicObjectrim:Slot[name=modified]rim:ValueListri
m:Value[1]ogc:PropertyName ogc:LowerBoundary
ogc:Literal2005-05-24T08-00:00-05:00ogc:Literal ogc:LowerBoundary
ogc:UpperBoundary ogc:Literal2005-05-24T08:30:00-05:00ogc:Literal
ogc:UpperBoundary ogc:PropertyIsBetween
ogc:Filter Constraint
Query GetRecords