Ontology & PHP - RAP Overview
an ontology is nothing else then a logical theory. The issue is whether such a theory needs to have particular formal properties in order to be an ontology or, rather, whether it is the intended purpose which lets us consider a logical theory as an ontology. The latter position can be supported by arguing that an ontology is an annotated and indexed set of assertion about something: “leaving o the annotations and indexing, this is a collection of assertions: what in logic is called a theory” (Pat Hayes statement in [24]). According to interpretation 4, an ontology is not viewed as a logical theory, but just as the vocabulary used by a logical theory. Such an interpretation collapses into 3.a if an ontology is thought of as a specification of a vocabulary consisting of a set of logical definitions. We may anticipate that the Gruber’s interpretation (specification of conceptualization) collapses into 3.a as well when a conceptualization is intended as a vocabulary. Finally, under interpretation 5, an ontology is seen as a specification of a logical theory in the sense that it specifies the “architectural components” (or primitives) used within a particular domain theory.
oldakowski-rap.pdf or http://www.semanticscripting.org/SFSW2005/papers/Oldakowski-RAP.pdf
http://www4.wiwiss.fu-berlin.de/bizer/rdfapi/tutorial/introductionToRAP.htm
RAP - RDF API for PHP is a Semantic Web toolkit for PHP developers. RAP started as an open source project at the Freie Universität Berlin in 2002 and has been extended with internal and external code contributions since then. Its latest release includes:
- a statement-centric API for manipulating RDF graphs as a set of statements
- a resource-centric API for manipulating RDF graphs as a set of resources
- integrated RDF/XML, N3 and N-TRIPLE parsers
- integrated RDF/XML, N3 and N-TRIPLE serializers
- in-memory or database model storage
- support for the RDQL query language
- an inference engine supporting RDF-Schema reasoning and some OWL entailments
- an RDF server providing similar functionality as the Joseki RDF server
- a graphical user-interface for managing database-backed RDF models
- support for common vocabularies
RAP can be used under the terms of the GNU LESSER GENERAL PUBLIC LICENSE (LGPL)
and can be downloaded from http://sourceforge.net/projects/rdfapi-php/
RAP offers two different programming interfaces for manipulating RDF graphs: The statement-centric Model API which allows you to manipulate an RDF graph as a set of statements; and the resource-centric ResModel API for manipulating an RDF graph as a set of resources.
The Model API supports adding, deleting, and replacing statements inside a model as well as adding entire models. StatementIterators allow sequential access to all statements within a model. There are four different implementations of the Model API:
| Model | Functionality |
|---|---|
| MemModel | Model storing its RDF graph in memory. MemModel is fast, but doesn’t support inference. |
| DbModel | Model storing its RDF graph in a relational database. No inference support. |
| InfModelF | Forward-chaining inference model storing its base graph and inferred triples in memory. |
| InfModelB | Backward-chaining inference model storing its base graph in memory and creating inferred triples on the fly. |
The resource-centric ResModel API represents RDF graphs as resources having properties. The ResModel API is very similar to the Jena Model API allowing programmers, which are used to Jena, to easily write RAP code. The ResModel API is implemented on top of the Model API. ResModels are always having a underlying MemModel, DbModel, InfModelF or InfModelB and are only providing a resource-centric view on this model. There are two implementations of the ResModel API:
| Model | Functionality |
|---|---|
| ResModel | Basic implementation of the ResModel API |
| OntModel | OntModel provides a ResModel implementation extended with RDF-Schema specific methods like hasSuperProperty(), addDomain() and listInstances(). |
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