L oosely coupled distributed systems are characterised by a separation of resources and a consequent need for a facility to aid in the location of those resources. Traditionally, this role of resource location has been fulfilled by a name service i.e. a facility which maps the name of a resource to its location at a given network address. As the size of the resource name space grows, however, additional support for resource location is required, in the form of support for the discovery of the name of the resource that is to be located. A trading facility implements an approach to resource location which eliminates the need to know the name of a resource in order to locate it and instead allows specification of a required service in an abstract manner. Resources (or services) are classified by type, and the location of such services is guided principally by a specification of the required service type, with requests for services being mapped directly to services of an appropriate type...

In this paper, we present and evaluate alternative techniques to effect the use of location-independent identifiers in distributed database systems. Location-independent identifiers are important to take full advantage of migration and replication as they allow accessing objects without visiting the servers that created the objects. We will show how a distributed index structure can be used for this purpose, we will present a simple, yet effective replication strategy for the nodes of the index, and we will present alternative strategies to traverse the index in order to dereference identifiers (i.e., find a copy of an object given its identifier). Furthermore, we will discuss the results of performance experiments that show some tradeoffs of the proposed replication and traversal strategies and compare our techniques to an approach that uses locationdependent identifiers like many systems today. 1 Introduction Large distributed systems are beginning to play a dominant role in the inf...

This document describes the Server Cache Synchronization Protocol (SCSP) and is written in terms of SCSP's use within Non Broadcast Multiple Access (NBMA) networks; although, a somewhat straight forward usage is applicable to BMA networks. SCSP attempts to solve the generalized cache synchronization/cache-replication problem for distributed protocol entities. However, in this document, SCSP is couched in terms of the client/server paradigm in which distributed server entities, which are bound to a Server Group (SG) through some means, wish to synchronize the contents (or a portion thereof) of their caches which contain information about the state of clients being served.