View source for 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===
{| {{table}}
| align="center" style="background:#f0f0f0;"|'''Name'''
| align="center" style="background:#f0f0f0;"|'''Description'''
| align="center" style="background:#f0f0f0;"|'''Type'''
| align="center" style="background:#f0f0f0;"|'''Protocol'''
| align="center" style="background:#f0f0f0;"|'''Framework'''
|-
|-
| [[#gCQLParser|gCQLParser]]||The gCube parser for CQL language (extended with gCube elements)||Java||Local||none
|-
| [[#Index Service|Index Service]]||Provides indexing functionality for the resources||WS||SOAP||[https://gcore.wiki.gcube-system.org/gCube gCore]
|-
| [[#OperatorLibrary|OperatorLibrary]]||The search operators cover the basic functionality that could be encountered in a typical search operation||Java||Local||none
|-
| [[#Search System Service|Search System Service]]||Web service that offers information retrieval functionality in a gCube infrastructure.||WS||SOAP||[https://gcore.wiki.gcube-system.org/gCube gCore]
|-
| [[#OpenSearch Library|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|OpenSearchService]]||The 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||[https://gcore.wiki.gcube-system.org/gCube gCore]
|-
| [[#aslHttpInformationRetrieval|aslHttpInformationRetrieval]]||REST API that provides aggregated access to mandated functionality for performing a gCube search.||Java Servlets||REST||[[Integration_and_Interoperability_Facilities_Framework:_HTTP_API_Framework_Specification|HTTP Front End]]
|-
| [[#aslHTTPContentAccess|aslHTTPContentAccess]]||REST API that provides access to aggregated functionality for accessing gCube Content.||Java Servlets||REST||[[Integration_and_Interoperability_Facilities_Framework:_HTTP_API_Framework_Specification|HTTP Front End]]
|-
| [[#aslHTTP_OAI_PMH|aslHTTP_OAI_PMH]]||REST implementation supporting OAI-PMH protocol for exposing gCube Metadata.||Java Servlets||REST||[[Integration_and_Interoperability_Facilities_Framework:_HTTP_API_Framework_Specification|HTTP Front End]]
|-
| [[#aslHTTP_OAI_ORE|aslHTTP_OAI_ORE]]||REST implementation supporting OAI-ORE protocol for representing gCube complex object support for OAI-ORE Specification for rendering gCube collections and documents as Resource Maps.||Java Servlets||REST||[[Integration_and_Interoperability_Facilities_Framework:_HTTP_API_Framework_Specification|HTTP Front End]]
|-
|}

==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''': [https://gcore.wiki.gcube-system.org/gCube gCore]
* [[Index_Management_Framework|'''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
* [[Search_Operators|'''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''': [https://gcore.wiki.gcube-system.org/gCube gCore]
* [[Search_Operators|'''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''

==OpenSearch Library==
* '''Description''': 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.
* '''Type''': CL
* '''Protocol''': Java
* '''Framework''': none
* [[OpenSearch_Framework#OpenSearch_Library|'''Documentation''']]
* '''Key Features'''
:* ''access to the information hosted by external Providers''
:* ''extensions provide functionality not only for standard OpenSearch parameters are supported''
:* ''the role of the OpenSearch Operator is to provide support for querying and retrieval of search results via OpenSearch from providers which expose an OpenSearch description document. ''
:* ''results are returned wrapped in a ResultSet''
:* ''support of data transformation by the operator''
:* ''both direct and brokered result processing is supported''
:* ''support of a set of fixed parameters, which override the user-provided parameters only at the level of the top provider''
:* ''MIME type of the results that are to be obtained is abstracted away and treated as low-level information which can be exploited by the way OpenSearch Resources are structured''
:* ''the operator accepts a set of query terms and a set of query parameters''
:* ''OpenSearch Operator expects to receive all query parameters. Any free-text parameter value should be URL-encoded''

==OpenSearchService==
* '''Description''': The OpenSearch Service is a stateful web service responsible for the invocation of the OpenSearch Operator in the context of the provider to be queried.
* '''Type''': WS
* '''Protocol''': SOAP
* '''Framework''': [https://gcore.wiki.gcube-system.org/gCube gCore]
* [[OpenSearch_Framework#The_OpenSearch_Service|'''Documentation''']]
* '''Key Features'''
:* ''uses a WS-Resource for each OpenSearch provider in order to bind the Service to the Metadata Collection corresponding to the provider.''
:* ''maintains a cache per provider WS-Resource for performance and reliability reasons''
:* ''he cache can be refreshed either on demand or periodically, based on a configurable time interval''