NPDS is a "who what where" diristry-registry-directory system for identifying, describing, locating and linking things on the internet, web and grid. PORTAL registries identify resources with unique labels and lexical tags in a manner compatible with the lexical web. DOORS directories specify locations and semantic descriptions for these identified resources in a manner compatible with the semantic web. PORTAL registries and DOORS directories were designed to be analogous to IRIS registries and DNS directories. This original design has been enhanced with Nexus diristries to provide integrated services combining the functions of both PORTAL registries and DOORS directories.

PDP provides anonymous user read access to resource metadata in the prototype Nexus diristries, PORTAL registries and DOORS directories as well as information on the continuing design, development, and implementation of NPDS as a cyberinfrastructure for semantic computing on the internet, web, and grid. Scribe registrar services are maintained at the following sites for resource metadata management at Nexus diristries, PORTAL registries and DOORS directories:

all of which require secure https connection for authorized agent write access. Resource metadata record agents with Author and/or Editor roles may access write privileges at the BHA, GTG and PDP Scribe Registrars, but not for management of NPDS components where write access is restricted to agents with Admin roles.

For comprehensive reports on NPDS, please refer to DOORS to the Semantic Web and Grid With a PORTAL for Biomedical Computing published online 3 August 2007 in the journal IEEE Transactions on Information Technology in Biomedicine and A Distributed Infrastructure for Metadata about Metadata: The HDMM Architectural Style and PORTAL-DOORS System published online 1 June 2010 in the journal Future Internet. More recent information can be found in the documents available at PDP Papers. These reports contain explanations of the principles, concepts, models, schemas, URL and querystring designs used by PDP for NPDS.

Nexus Sites (anonymous)

Scribe Sites (authenticated)