Thea Open Calais wrapper module

1 Introduction

Open Calais is a Web service provided by Thomson Reuters. Open Calais analyses content using NLP and semantic tecnniques and returns an RDF based response containing entities and relationships identified in the source and associated metadata.

thea_opencalais is a Prolog wrapper for accessing Open Calais and process the results. It is an application of Thea prolog library for OWL2 Ontologies. thea_opencalais uses the OpenCalais ontology and parses the service response first into Ontology axioms and finally into prolog terms and predicates, accessible from within a prolog program.

2 Example

Get your Open Calais license key and assert it as a prolog fact:

     :- assert(thea_opencalais:open_calais(license('Your open calais license key'))).

Load the Open Calais Ontology into Prolog using Thea.
```
    :- owl_parse_rdf('owl.opencalais-4.3.xml.owl',[imports(false),clear(complete)]).
```
The Ontology in this example has been already downloaded in the working directory. Originaly it can be found here

Post the content of a Wikipeadia page about papal visits to the Open Calais REST service

    :- oc_rest(http('http://en.wikipedia.org/wiki/List_of_journeys_of_Pope_Benedict_XVI'),'',_X).

Use Prolog provided prolog predicates to examine Markup Elements (Entities and Relationships) in the result

 :-oc_entity(A,B,C,E,D).
       A = 'http://d.opencalais.com/genericHasher-1/f545c2a6-ccd3-3095-adb0-c1c8dda96624',
       B = 'http://s.opencalais.com/1/type/em/e/Anniversary',
       C = ['http://s.opencalais.com/1/pred/name'=literal('the 500th anniversary of Catholic presence')],
       E = [instance_info('http://d.opencalais.com/dochash-1/2d1827f8-c251-36b1-bfe6-043a4a6caba1/Instance/268', [.....
       D = []

You can also write custom predicates to query the resulted database of Markup Elements e.g.

    quotation(Person,Quotation) :-
            oc_relation(_I,'http://s.opencalais.com/1/type/em/r/Quotation',PVList),
            pv_attr('http://s.opencalais.com/1/pred/person',PVList,Person),
            pv_attr('http://s.opencalais.com/1/pred/quote',PVList,Quotation).

3 Predicate reference

oc_rest(+Request, +Params:string, -Result) is det

Calls Open Calais Rest service and posts the Request. Requires a valid Open_Calais license key in a dynamic open_calais(license(License)) to be asserted.

Parameters:

`Request`	- can be any of the following: http`(URL)` file`(Filename)` text`(Atom)`
`Params`	- is a string encoded XML see description in http://www.opencalais.com/APICalls
`Result`	- is the RDF response of Open_Calais see http://www.opencalais.com/documentation/calais-web-service-api/interpreting-api-response/rdf

oc_entity(?I, ?C, -PV:list, +Instance:list, +Resolutions:list) is nondet

Returns the markup element entities in the response to an Open Calais request

Parameters:

`I`	- is the returned markup entity ID (IRI)
`C`	- is the entitie's markup type
`PV`	- list of property value pairs for the entity
`Instance`	- List of instance_info terms for the specific entity
`Resolutions`	- List of resolution terms for the specific entity

oc_relation(?I, ?C, -PV:list) is nondet

Returns the markup element relations in the response to an Open Calais request

Parameters:

`I`	- is the returned markup relation ID (IRI)
`C`	- is the relation's markup type
`PV`	- list of property value pairs for the relation

oc_resolution(?R, ?C, -PV:list) is nondet

Returns the resolutions in the response to an Open Calais request

Parameters:

`R`	- is the returned resolution ID (IRI)
`C`	- is the resolution's type
`PV`	- list of property value pairs for the resolution

4 Download and use

Thea and thea_opencalais are open source licensed under GPL and are hosted on github. thea_opencalais module and examples can be found in apps/opencalais folder