Transitive indexing allows users and applications to locate files and objects across the network by building indices for hierarchical information based on attributes from the current node and summaries from other indices. Transitive indexing is designed to be scalable in an environment lacking centralized administrative control. PFAP provides a single uniform interface to multiple caching mechanisms including whole file caching and block caching depending on the reference characteristics of the data and the requirements of clients and servers. PFAP has been integrated with security and payment mechanisms to support controlled access to data objects with restricted access policies. The GOST project has developed a new efficient garbage collection algorithm for distributed systems using the propagation of last referencable time and registration of links.
Garbage collection allows the reclamation of storage for objects which are no longer needed.
Support for link maintenance has been developed as part of the garbage collection algorithm, allowing the update of references to objects that have moved across nodes. Through the work of the GOST project on replication, multiple replication methods and associated consistency algorithms are supported. The specific method to be used may be specified at the granularity of individual objects, files, or directories based on the characteristics and requirements of the individual object, file, or directory. Where existing methods do not meet the needs of an object, application specific methods may be inserted into and are supported by the GOST framework for replication. The PDS provides a common access protocol through which applications and middleware can retrieve and modify directory information and object attributes.