Introduction
 



Oyster is a java-based system, which assists researchers in managing, searching and sharing ontology metadata in a peer-to-peer network.

Currently, ontology re-use is rather difficult, as it is hard to find and share ontologies available among the community. This leads to the problem of having many isolated ontologies created by many different parties. Besides the costs of the duplicate efforts this also hampers interoperability between ontology-based applications. Oyster 1 is a Peerto-Peer application that exploits semantic web techniques in order to provide a solution for exchanging and re-using ontologies

Besides, the Oyster client on its own (e.g. disconnected from the P2P network) provides added value to it's users as it will give researchers an overview and search facilities of his/her own ontology metadata.

A possible inquiry could be: I am searching for ontologies about a specific domain like publications or for ontologies developed in a specific language like OWL. As a result Oyster returns ontology metadata entries concerning those types of ontologies.

In order to provide this funcionalities, Oyster implements a proposal for a metadata standard, so called Ontology Metadata Vocabulary (OMV) which is based on discussions and agreement in the EU IST thematic network of excellence Knowledge Web as the way to describe ontologies. OMV has evolved through time to better fulfill the initial requirements (For the description of the attributes needed to create a new entry in Oyster (part of OMV definition) see definitions For OMV full definition or for download OMV in OWL refer to http://ontoware.org/projects/omv/ You can also find the publications related to Oyster and OMV here).









 
 

Architecture
 



Oyster, is an application based on technologies of SWAP - a system combining Semantic Web and Peer-to-peer technologies.

  
   
 

Peer-to-Peer systems are characterized as distributed systems without any centralized control or hierarchical organization. Each node in the system runs software with equivalent functionality. The main features of Peer-to-Peer applications yields a long list: redundant storage, permanence, selection of nearby servers, anonymity, search, authentication, and hierarchical naming.

The Semantic Web is an extension of the current web in which information is given well-defined meaning, better enabling computers and people to work in cooperation. In a distributed knowledge management system these Semantic Web techniques can be used to express knowledge shared by peers in a well-defined and formal way.

SWAP provides the technology that is necessary to allow users their individual views on knowledge and let them share knowledge effectively. In order to allow for individual views, every user is treated as a peer and every user may ask queries to the network of peers. In order to actually find the right piece of knowledge, SWAP employs Semantic Web technology. Current peer-to-peer technology only allows for keyword search and lacks the semantics that is necessary for effective, precise knowledge sharing. Current knowledge repositories lack the capability to provide really individual views in a decentralized framework with low administration overhead. SWAP will produce both.

SWAP is a project funding as a shared-cost R&D in the European Commission Information Societies Technology (IST) programme.

  
 

 
 

Usage
 

Scope

You can select the scope of your query:

  • Local Peer: Restrict your query to your local peer.
  • Automatic Search: Intelligent selection of peers.
  • Selected Peers: Select a set of peers (figure 1).

  
   
 


Search details

You can restrict your query to special attributes (e.g. search for ontologies in OWL), or for ontologies about a specific subject (based on the classification ontology loaded, such as DMOZ), or you can search for a string match in any attribute. Furthermore, you can search ontologies by their namespace (uri), and the result will show all the ontologies that includes the words on the uri field on their namespace.

 
 

Save items to your local repository

You can save items to your local node repository by simply selecting the item and pressing the "Save" button.

 
 

Adjusting the columns in the result view

By pressing the right mouse button inside the result view panel you can adjust your personal view (figure 2).

 
   
 


Create and Edit items

New ontology metadata entries can be created from scratch, or existing ones can be modified. Oyster provides two templates for default to create a new metadata entry from scratch: OntologyDocumentFull which includes all the attributes proposed in OMV, and OntologyDocumentRequired which includes only the attributes the OMV propose as required. You can also create your own templates or you can create the metadata entry without using templates and just adding the attributes you want to include. It is important to notice that the docName and uri attributes are mandatory in order to create a new metadata entry. Figure 3 shows Oyster's "Edit editor".

  
   
 


Import functions

It is possible to import an ontology file document to extract the ontology metadata and then fill missing values. Oyster supports the OWL, DAML+OIL and RDF-S ontology languages. Also, a complete repository (a RDF file) can be imported into the local repository (Figure 4).

 
   
 


Export repository

The repository can be exported to a HTML file (based on a configurable XSLT file) or to a RDF file. It is also possible to export individual entries (Figure 5).

 
   
 


Preferences

The classification ontology loaded by default is based on DMOZ, but it is possible to load different classification ontologies by changing which file to open in the preferences menu.

 
 

Aggregation in result view

The aggregate function, identifies the Ontology Documents that are different realizations of the same Ontology as proposed by OMV (Figure 6).

 
   
 



Snapshots
 


Main View:
   
 


Edit item:
 




 
 


Download
 

Latest Version

Note for linux: unzip the file within the directory you want to install Oyster and run start.sh. The first time you run Oyster and your are asked for your peer name, the 3 first characters are automatically selected every time you introduce one, just deselect each time, please.


  
 

To see all releases go to ontoware.org pages:











 
 


Publications
 

Latest Version



















 
 

Credits
 

Developed by
 

UPM

University of Karlsruhe



 
 

Acknowledgments
 

KWeb Project (Part of WorkPackage 1.2)

SWAP Team








 
 

Contact
 

Feel free to contact us with your comments, questions, or suggestions.

 
 

FAQ
 

Question: I do not see any peers except my local peer

Answer: Try the following:

  • Check if your Internet connection is working
  • Check if you can ping your RDV/Relay server (e.g. 129.13.251.25 / 130.37.30.74). If this fails you might have problems with your internet connection. Please contact your local administrator.
  • Check if you can connect to your RDV/Relay server with telnet on port 9700 (e.g. telnet 130.37.30.74). If you cannot connect to the RDV/Relay sever you will get a connection error. Perhaps your firewall blocks the connection.
  • IMPORTANT: PLEASE DO THE FOLLOWING, WE HAVE NEW RDV/RELAY SERVER: Edit the PlatformConfig file of your Oyster peer (\Oyster application\bin\.jxta\PlatformConfig). Replace the IP address 129.13.251.25 in the file with the IP address of the new RDV/relay server 138.100.11.159 (It appears 2 times in the file)

  
 

Links