The Web Search Service wraps up the access to a web-based search page and retrieves the results and puts them into the standard Grassroots results format.
To build this service, you need the grassroots core and grassroots build config installed and configured.
The files to build the Web Search service are in the build/<platform> directory.
If you enter this directory
cd build/linux
you can then build the service by typing
make all
and then
make install
to install the service into the Grassroots system where it will be available for use immediately.
Each external search engine that you wish to wrap is defined in a JSON-based configuration file. These configuration files are stored in the references folder at the root level of the Grassroots server installation directory.
It uses a JSON file that has the standard Grassroots schema describing its operations, parameters, etc. along with the following additional keys:
- plugin: This is set to web_search_service.
- uri: The web address of the search page to use.
- method: This states the method used to send the query to the search page.
- POST: To send the search query as an HTTP POST request.
- GET: To send the search query as an HTTP GET request.
- selector: The CSS selector to get each of the resultant hits from the search page's response.
The referred service accesses this functionality be setting the plugin key to web_search_service. This web search instance can then be configured for the particular web site that is being wrapped.
For example, a Grassroots server can access the search engine at Agris. It has an html search form which submits queries to http://agris.fao.org/agris-search/index.do?query=value and the results are displayed with entry appearing in a div.result-item h3 a css selector. The configuration file shown below wraps this up into being searchable from Grasssroots using the web search service.
{
"schema_version": 1.0,
"provider": {
"name": "Agris",
"description": "A service to search for academic articles.",
"uri": "http://agris.fao.org/agris-search/index.do"
},
"services": {
"service_name": "Agris Search service",
"description": "A service to obtain articles using search terms",
"plugin": "web_search_service",
"operations": {
"operation_id": "Agris Web Search service",
"description": "An operation to obtain matching articles from Agris",
"about_uri": "http://agris.fao.org/agris-search/index.do",
"uri": "http://agris.fao.org/agris-search/searchIndex.do",
"method": "GET",
"selector": "div.result-item h3 a",
"parameter_set": {
"parameters": [{
"param": "query",
"name": "Query",
"default_value": "",
"current_value": "",
"type": "string",
"grassroots_type": "params:keyword",
"description": "The search term"
}]
}
}
}
}