What is the GEO DAB
GEO DAB is a key component of the GEOSS Common Infrastructure (GCI), transparently connecting GEOSS User’s requests to the resources shared by the GEOSS Providers.
GEO DAB scope is to simplify cross and multi-disciplinary discovery, access, and use (or reuse) of disparate data and information.
GEO DAB is a brokering framework that interconnects hundreds of heterogeneous and autonomous supply systems (the enterprise systems constituting the GEO metasystem) by providing mediation, harmonization, transformation, and QoS capabilities.
How it works
The GEO DAB applies the broker pattern, which separates users of services (clients) from providers of services (servers) by inserting an intermediary, called a broker. When a client needs a service, it queries a broker via a service interface. The broker then forwards the client's service request to a server, which processes the request. The GEO DAB presently provides broker components for discovery, access, semantics-enabled search.
Step by Step
The GEO DAB intercats with external systems by means of softare modules called Profilers and Accessors.
The following high-level steps are executed upon uers' requests.
Search
Users search for data on the client application.
Query Submission
The client application submits query to the GEO DAB. The profiler translates the query to the GEO DAB internal query language.
Query Distribution/Mediation
The accessors translate the query according to the external service interfaces and distribute it to the external systems.
Query Execution
External systems execute the query and return response to the GEO DAB. The accessors translate the results to GEO DAB internal data/metadata model.
Result Harmonization
The GEO DAB harmonizes results from the accessors and returns them to the profiler that translates the harmonized result according to its specific service interface and returns it to the client applications.
Result Display
The client application presents the results to users.
Supported Standards
Profilers
Each profiler is in charge of publishing a service interface which client applications can connect to (e.g. an OGC CSW interface, an OpenSearch interface, etc). Each incoming request is translated by the profiler into the GEO DAB internal query language. After GEO DAB has executed the request, profilers translate the result according to what is required by the client application.The GEO DAB presently provides profilers for the following service interfaces.
OGC CSW 2.0.2 AP ISO 1.0
OGC CSW 2.0.2 ebRIM EO
OGC CSW 2.0.2 ebRIM CIM
ESRI GEOPORTAL 10
OAI-PMH 2.0
OpenSearch 1.1
OpenSearch 1.1 ESIP
OpenSearch GENESI DR
CKAN
CUAHSI HIS-Central
ESRI REST API 10.3
Accessors
Each accessor is in charge of connecting to external servers publishing a specific service interface (e.g. OAI-PMH, OGC WCS, etc). Accessors translate requests expressed according to the GEO DAB internal query language into requests expressed according to the external system one. Besides, they execute data and metadata model mapping from the external ones to the GEO DAB internal ones. The GEO DAB presently provides accessors for the following service interfaces.
OGC WCS 1.0.0, 1.1.2, 2.0.1
OGC WMS 1.1.1, 1.3.0
OGC WFS 1.0.0, 1.1.0, 2.0.0
OGC WMTS 1.0.0
OGC SOS 1.0.0, 2.0.0, 2.0.0 Hydro Profile
OGC WPS 1.0.0
OGC CSW 2.0.0 Core
OGC CSW 2.0.2 AP ISO 1.0
OGC CSW 2.0.2 ebRIM/EO AP
OGC CSW 2.0.2 ebRIM/CIM AP
IRIS Station
HYRAX THREDDS SERVER 1.9
OAI-PMH 2.0
GBIF
DIF
HYDRO
UNAVCO
CDI 1.04, 1.3, 1.4
ISO19115-2
THREDDS 1.0.1, 1.0.2
THREDDS-NCISO 1.0.1, 1.0.2
THREDDS-NCISO-PLUS 1.0.1, 1.0.2
INPE
CKAN