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The EuroGEOSS Broker - Technical Documentation |
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The EuroGEOSS Broker extended interface is described in the EuroGEOSS Public Deliverable 2.2.2. This page provides few technical documentations concerning the EuroGEOSS Broker extended interface. These descriptions are published to facilitate the development of client components accessing the EuroGEOSS Broker (i.e. implementing its interface). Since the EuroGEOSS Broker interface is based on the GI-cat framework, other useful information can be found on the GI-cat documentation pages. |
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The operations of the EuroGEOSS Broker extended interface are listed in Table 1: |
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Table 1 - EuroGEOSS Broker operations |
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Operation |
Description |
Binding |
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GetResource |
Retrieve the resource with the given id |
HTTP/SOAP |
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GetContent |
Browse the children resources of a resource |
HTTP/SOAP |
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Query |
To perform a query on the catalog |
HTTP/SOAP |
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Status |
To retrieve feedback on a previous request |
HTTP/SOAP |
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Cancel |
To terminate a previous query operation |
HTTP/SOAP |
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GetAccessParameters |
Retrieves the XForms fields needed by broker to access a given resource |
HTTP/SOAP |
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GetData |
Gets the binary data block associated to a resource OR the URL to use for subsequent data access OR the preview of the given resource |
HTTP/SOAP |
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GetBrokerCapabilities |
Retrieves Catalog Capabilities (e.g. supported interfaces) |
HTTP/SOAP |
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GetActiveConfiguration |
Retrieve the configuration currently in use by broker |
HTTP/SOAP |
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InsertConfiguration |
Store a new catalog configuration |
HTTP/SOAP |
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ActivateConfiguration |
Activate a stored configuration |
HTTP/SOAP |
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DeleteConfiguration |
Remove a configuration |
HTTP/SOAP |
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GetConfigurations |
Retrieve the named configuration or a full list |
HTTP/SOAP |
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The UML diagram depicted below shows the conceptual data model implemented by the EuroGEOSS broker; it supports geospatial data cataloging, discovery and access.
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Click on the image to enlarge it. |
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The XML schema encoding of the Broker Data Model can be downloaded here. |
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The Broker query operation allows to discover the federated resources that satisfy the query constraints (i.e. the query clauses). These constraints are expressed in the csw:GetRecords parameter. This element can be encoded as an XML document according to several supported schemas: CSW Core, CSW ISO, CSW ebRIM/CIM, CSW ebRIM/EO. To identify the schema utilized for a given csw:GetRecords element, the Uniform Resource Name (URN) of the corresponding OGC standard is used (see Table 2).
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Table 2 - URNs used in the Query operation |
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urn:ogc:serviceType:CatalogueService:2.0.2:HTTP |
OGC Catalogue Service 2.0.2 (HTTP Binding) |
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urn:ogc:serviceType:CatalogueService:2.0.2:HTTP:ISO19115/19119 |
OGC Catalogue Service 2.0.2 (HTTP Binding , 19115/19119 Profile) |
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urn:ogc:serviceType:CatalogueService:2.0.2:HTTP:ebRIM:CIM |
OGC Catalogue Service 2.0.2 (HTTP Binding, ebRIM Profile, CIM Extension Package) |
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The XML documents used for exchanging messages between the Broker (i.e. the server component) and a client component implement the following UML diagrams –divided into four main functional modules: |
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Click on one image to enlarge it. |
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The XML schema encoding of the UML diagrams are available here.
XML messages by example are available here. |
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Both GetData and GetAccessParameters operations need a way for identifying the protocol to be used for accessing selected data. Where possible, standard URNs are chosen (e.g. the OGC URNs). Alternatively, strings are used: they are constructed following the same principle adopted by OGC URNs. The used conventions are listed in Table 3. |
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Table 3 - Conventional URNs used in GetData and
GetAccessParameters operations |
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Convention |
Protocol |
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urn:ogc:serviceType:WebCoverageService:1.1.0 |
OGC Web Coverage Service 1.1.0 |
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urn:ogc:serviceType:WebMapService:1.1.1 |
OGC Web Map Service 1.1.1 |
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urn:ogc:serviceType:WebMapService:1.3.0 |
OGC Web Map Service 1.3.0 |
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urn:ogc:serviceType:WebFeatureService:1.0 |
OGC Web Feature Service 1.0 |
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HTTP |
HTTP protocol |
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opendap :serviceType:opendap |
OPeNDAP | |
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