Skip to main content
Go Search
Logo Seventh Framework Programme Logo European Commission
EuroGEOSS
About the project
Outreach
Resources
About us
Publications
EuroGEOSS Conferences
  

The EuroGEOSS Broker - Technical Documentation

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.

 

 List of operations

The operations of the EuroGEOSS Broker extended interface are listed in Table 1:

Table 1 - EuroGEOSS Broker operations

Operation

Description

Binding

GetResource

Retrieve the resource with the given id

HTTP/SOAP

GetContent

Browse the children resources of a resource

HTTP/SOAP

Query

To perform a query on the catalog

HTTP/SOAP

Status

To retrieve feedback on a previous request

HTTP/SOAP

Cancel

To terminate a previous query operation

HTTP/SOAP

GetAccessParameters

Retrieves the XForms fields needed by broker to access a given resource

HTTP/SOAP

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

GetBrokerCapabilities

Retrieves Catalog Capabilities (e.g. supported interfaces)

HTTP/SOAP

GetActiveConfiguration

Retrieve the configuration currently in use by broker

HTTP/SOAP

InsertConfiguration

Store a new catalog configuration

HTTP/SOAP

ActivateConfiguration

Activate a stored configuration

HTTP/SOAP

DeleteConfiguration

Remove a configuration

HTTP/SOAP

GetConfigurations

Retrieve the named configuration or a full list

HTTP/SOAP

 

 Internal Data Model

The UML diagram depicted below shows the conceptual data model implemented by the EuroGEOSS broker; it supports geospatial data cataloging, discovery and access.

 

Click on the image to enlarge it.

 

The XML schema encoding of the Broker Data Model can be downloaded here.

 Uniform Resource Names (URNs) for Query Operation

   

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).

 

 Table 2 - URNs used in the Query operation

URNs used in the Query Operation

Description

urn:ogc:serviceType:CatalogueService:2.0.2:HTTP

OGC Catalogue Service 2.0.2 (HTTP Binding)

urn:ogc:serviceType:CatalogueService:2.0.2:HTTP:ISO19115/19119

OGC Catalogue Service 2.0.2 (HTTP Binding , 19115/19119 Profile)

urn:ogc:serviceType:CatalogueService:2.0.2:HTTP:ebRIM:CIM

OGC Catalogue Service 2.0.2 (HTTP Binding, ebRIM Profile, CIM Extension Package)

urn:ogc:serviceType:CatalogueService:2.0.2:HTTP:ebRIM:EO

OGC Catalogue Service 2.0.2 (HTTP Binding, ebRIM Profile, EO Extension Package)

 Messages

 

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:

 

 

 

 Click on one image to enlarge it.

The XML schema encoding of the UML diagrams are available here.

XML messages by example are available here.

 

 Conventions for Access Protocol Identification

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.
 

Table 3Conventional URNs used in GetData and

GetAccessParameters operations

Convention

Protocol

urn:ogc:serviceType:WebCoverageService:1.1.0

OGC Web Coverage Service 1.1.0

urn:ogc:serviceType:WebMapService:1.1.1

OGC Web Map Service 1.1.1

urn:ogc:serviceType:WebMapService:1.3.0

OGC Web Map Service 1.3.0

urn:ogc:serviceType:WebFeatureService:1.0

OGC Web Feature Service 1.0

HTTP

HTTP protocol

opendap :serviceType:opendap

OPeNDAP