ÐIn current distributed systems, the notion of mobility is emerging in many forms and applications. Mobility arises naturally in wireless computing since the location of users changes as they move. Besides mobility in wireless computing, software mobile agents are another popular form of moving objects. Locating objects, i.e., identifying their current location, is central to mobile computing. ...

This article illustrates how to easily address scalability issues within distributed applications built on top of the Coordination Language Facility (CLF) middleware. CLF provides a distributed object computing framework with high expressiveness, flexibility and dynamicity. Our solutions rely on a core set of techniques such as replication, caching and distribution. We decline them along a geog...

This paper presents an overview of key factors a ecting performance of Web sites which may be using Web services protocols. We show how Web sites can be scaled with load balancers sending requests to multiple servers which can be distributed for both improved performance and availability. Caching, load balancing, and replication are critical components for achieving good performance and high av...

Reliable data multicast is problematic. ACK/NACK schemes do not scale to large audiences, and simple data replication wastes network bandwidth. Fcast, " file multicasting " , combines multicast with Forward Error Correction (FEC) to address both these problems. Like classic multicast, Fcast scales to large audiences, and like other FEC schemes, it uses bandwidth very efficiently. Some of the be...

This paper describes the design, implementation and usage of a secure scalable Byzantine fault tolerant MDS system in the Grid. The scalable Byzantine fault tolerant MDS system provides a hierarchy GIIS servers, a local GIIS domain can require the resource it needs from remote GIIS domain. By using the statemachine replication approach and quorum system technique, the scalable Byzantine fault t...

We present the design and evaluation of the query-routing protocol of the TerraDir distributed directory. TerraDir is a wide-area distributed directory designed for hierarchical namespaces, and provides a lookup service for mapping keys to objects. We introduce distributed lookup and caching algorithms that leverage the underlying data hierarchy. Our algorithms provide efficient lookups while a...

In this technical report we describe a flexible storage system aimed at supporting collaborative applications in large-scale environments that include mobile computers. In such settings two major problems arise: data availability and concurrent updates merging. The first is tackled by the combination of weakly consistent server replication and client caching. The second, through an open object ...

We present the MINERVA project that tackles the problem of collaborative search across a large number of digital libraries. The search engine is layered on top of a Chord-style peer-to-peer overlay network that connects an a-priori unlimited number of peers or digital libraries. Each library posts a small amount of metadata to a conceptually global, but physically distributed directory. This di...

Crucial performance metrics of a caching algorithm include its ability to quickly and accurately learn popularity distribution requests. However, majority work on analytical analysis focuses hit probability after an asymptotically large time has elapsed. We consider online learning viewpoint, characterize the “regret” in terms finite difference between hits achieved by candidate w...