Data Retrieval APIs

Data Retrieval APIs provide access to to Information Retrieval facilites over large heterogeneous environments, offering a declarative approach for querying the hosted information and allowing for easy integration of external data sources of information.

This page outlines the design rationale for those APIs.

Overview

Name	Description	Type	Protocol	Framework
gCQLParser	The gCube parser for CQL language (extended with gCube elements)	Java	Local	none
Index Service	Provides indexing functionality for the resources	WS	SOAP	gCore
OperatorLibrary	The search operators cover the basic functionality that could be encountered in a typical search operation	Java	Local	none
Search System Service	Web service that offers information retrieval functionality in a gCube infrastructure.	WS	SOAP	gCore
OpenSearch Library	The OpenSearch Core Library conforms to the latest OpenSearch specification and provides general OpenSearch-related functionality to any component which needs to query OpenS earch providers.	CL	Local	none
OpenSearchService	TThe OpenSearch Service is a stateful web service responsible for the invocation of the OpenSearch Operator in the context of the provider to be queried.	WS	SOAP	gCore

gCQLParser API

• Description: Provides functionality that helps presentation layer to use gCube services.
• Type: Local
• Protocol: Java
• Framework: none
• Documentation
• Key Features

• submission of gCQL queries as plain string
• support for gCube extensions in CQL language for presentable information

Index Service API

• Description: Provides indexing functionality for the resources.
• Type: WS
• Protocol: SOAP
• Framework: gCore
• Documentation
• Key Features

• Full Text Index receives CQL queries and transforms them into Lucene queries
• 2 linguistics components are available; the language identifier module, and the lemmatizer module
• database partitioning is supported
• geo-spatial Index Lookup supports one custom CQL relation
• the "geosearch" relation has a number of modifiers that specify parameters such as collection, language, query inclusion type, refiner and ranker
• support of customs refiners and rankers
• the content to be fed into a Geo Index, must be served as a ResultSet containing XML documents conforming to the GeoROWSET schemafield presense and handling by the Geo Index is specified through a GeoIndexType; an XML document conforming to the GeoIndexType schemathe content to be fed into a Geo Index, must be served as a ResultSet containing XML documents conforming to the GeoROWSET schema

OperatorLibrary

• Description: The search operators cover the basic functionality that could be encountered in a typical search operation.
• Type: CL
• Protocol: Java
• Framework: none
• Documentation
• Key Features

• results are transfered via ResultSet
• the comparing parts are either literals (date, string, integer, double literals are supported) or aggregate functions on the results of a search service execution

Search System Service

• Description: Web service that offers information retrieval functionality in a gCube infrastructure.
• Type: WS
• Protocol: SOAP
• Framework: gCore
• Documentation
• Key Features

• queries expressed in Contextual Query Language
• orchestration of search plan production and execution
• transparent detection and utilization of Data Sources
• results streaming exposition through gRS2 endpoint