The PORTAL-DOORS Project (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 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.

A comprehensive paper describing the Nexus-PORTAL-DOORS System (NPDS), entitled A Distributed Infrastructure for Metadata about Metadata: The HDMM Architectural Style and PORTAL-DOORS System , was published 2010 June 1 online in the journal Future Internet. More recent information can be found in the documents available at NPDS Papers. These reports contain explanations of the concepts, models, schemas, URL and querystring designs used by PDS.