The logic behind resource discovery is that of peer to peer systems: making resources dynamically available and thus re-usable by other resources, which can benefit from the functionality or the information they provide. D-NET marries the same principles, but providing a resource model richer than those of peer to peer systems. Resource providers can dynamically register their resources, i.e., making them available to the infrastructure, or de-register their resources, i.e., making the abandon the infrastructure. To this aim, resources register to an infrastructure by communicating their profile to the Information Service of such infrastructure. A profile is a machine-interpretable description (i.e., XML file of established format) of a resource, thus it includes information such as: identity (unique in the system and assigned by Information Service at registration time), location (WSDL URL), resource type (vocabulary available to Information Service, see below for more), status of the resource (special fields, specific to the resource type).  Resources must keep their profiles updated to the IS, aligned with the latest status changes.