Copyright © OGC 2010
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main application for accessing GEOSS services. The clearinghouse provides search capability across a distributed network of catalogue services. The registry publishes metadata describing components and
services registered in GEOSS.
An instantiation of the above architecture is being deployed under the Heterogeneous Missions Accessibility [RD5] initiative of the European Space Agency as shown on the next figure. The Community Clients are the
main applications for accessing the EO services. The EO Community Clearinghouse accessible from the GEO Web Portal provides search capability across a distributed network of catalogue services. The EO
Community Service and Collection catalogue publishes ISO metadata describing Community resources e.g. EO dataset series i.e. collections and services registered and their interrelationships. Types of service
registered include catalogues, ordering services, sensor planning services and Web mapping services. In addition, conformance test capabilities are available based on the OGC CTL language and the TEAM test
engine.
Figure 4 Example of GEOSS Tiers Instantiation for the European Union
9.2.5 Technology Viewpoint
The GEOSS Registry provides a catalogue of all registered components and services. The following requirements apply to technologies contributed to GEOSS:
Upon registering a service, a service provider must specify the length of time for which the service will be offered preferably ‗unlimited‘.
Experimental services will be registered and exempt from the level of service requirements. Services are expected to be available at least 99 of the time, except when otherwise required by the nature
of the service. This allows for approximately 7 hours of down time a month. Adequate network service must be utilized in order to provide this level of availability.
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Non-functioning components of the Network will diminish the operational and marketing value of the Network in general for all participating organizations. Therefore, GEO may remove a listed server from the
registry
9.2.5.1 Component Implementation
I
t should be noted that GEOSS is a system of contributed systems, components and services. Therefore, contributors have adopted a variety of technologies for implementing the components contributed to GEOSS. In this sub-section we
have selected some of the components and instances that have been used in the AIP and associated tasks. Community portals: A community-focused portal website that provides a human user interface to
identified content. Some of the component instances used include ESRI GIS Portal toolkit, Compusult, ESAFAO portal products.
Client applications: Application hosted on users computer to access remote services and provide manipulation of the data in the client application. Clients may be specific to a user community or
may be more generic geospatial data applications. Some of the clients that have been used to interact with GEOSS components during AIP-2 included web browsers Internet Explorer, Mozilla
Firefox, UDig used as WPS client, Google Earth and ERDAS TITAN.
Community catalogues: Collection of community-organized information descriptions metadata exposed through standard catalog service interfaces. Example component instances used include
catalogue servicesCSW bundled with ESRI GIS Portal toolkit and another developed by George Mason University.
Workflow management: Encapsulates an engine capable of managing workflows, services, activities, and workflow execution instances. An example instance is BPELPower developed by
George Mason University. GMU BPELPower BPEL engine is a generic BPEL workflow execution engine. Another workflow engine is Oracle BPEL Process Manager used by ESA Service Support
Environment SSE.
Processing services: Components that accepts requests to process data using an algorithm hosted in the component. The data is accessed from a remote service. The processing services used in
AIP-2 were offered through instances of the 52North WPS.
GEONETCast: Global network of satellite-based data dissemination systems to distribute data via broadcast. The GEONETCast multicasting allows different datasets or EO products to be
transmitted in parallel from satellites or in-situ sensors. Access to data is controlled and targeted to specific groups of users through a key access capability. The multicast capability uses a global
network of communications satellites that includes direct-to-home DTH telecommunication satellites and Digital Video Broadcast DVB. GEONETCast is describes in detail by Wolf L. and
Williams M. 2008 GEONETCast
—Delivering Environmental Data to Users Worldwide IEEE Systems Journal, pp. 401-405, 23 DOI 10.1109JSYST.2008.925978
9.2.5.2 Run-time Environment
There are no requirements in GEOSS for specific run-time requirements. Components and Services within GEOSS are implemented in a variety of run-time environments.
9.2.5.3 Deployed Service Instances and Networks
The following are lists of Components and Services currently registered in the GEOSS Registry. The following table is a list of components catalogued in the GEOSS Registry exported on September 9th 2009.
1. 52°North SOS Client
Details 2.
AIRNow Gateway Web Service Details
TBC with list of other components
