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An approach towards an agent computing environment
(Research report; Forskningsrapport, 1998)We devise a mobile agent middleware architecture for supporting distributed applications in a wide-area network. The architecture provides a structural framework for functional components that are needed to support mobile agents in asymmetric networking environments. -
Authorization and access control in a distributed file repository
(Research report; Forskningsrapport, 1999-01-18)A distributed file repository is described. It supports interaction between different machines used by a single user, as well as between users that share data. Files can be replicated and consistency will be maintained, or files can be shipped (copied) to a remote site. As with more traditional systems, the servers are trusted not to leak information. However, the rôle servers play is not as much ... -
Adding mobility to non-mobile web robots
(Research report; Forskningsrapport, 2000)In this paper we will show that it is possible to combine mobile agent technology with existing non-mobile data mining applications. The motivation for this is the advantage mobile agents offer in moving the computation closer to the data in a distributed system. This can save bandwidth and increase performance when the data is condensed as a result of data mining. -
TOS: A Kernel of a Distributed Systems Management System
(Research report; Forskningsrapport, 2000-03-02)Distributed systems are becoming harder to manage, in part because the uses we put to distributed systems are rapidly changing. Hence, the software used to manage a distributed system needs to be flexible enough to accommodate these new uses. It also has to be secure enough to not allow unauthorized changes to be made to the system. We present a library and a kernel that supports the management ... -
An extensible software architecture for mobile components
(Research report; Forskningsrapport, 2000-10-06)This paper presents a generic software architecture for large-scale distributed applications where mobile agents are an integral part. We have devised this architecture through completion of a series of mobile agent systems and associated applications over the last 8 years. -
Building agent applications using wrappers
(Research report; Forskningsrapport, 2001-01-11)For the past seven years, the TACOMA project has investigated software support for mobile agents. Several prototypes have been developed, with experiences in distributed applications directing the effort. This paper presents a new mechanism that supports implementing agent applications by creating troops of agents using wrappers. This solution requires little extra support from the agent system, and ... -
Separating mobility from mobile agents
(Research report; Forskningsrapport, 2001-01-16)In this paper we argue that the traditional model of a mobile agent provides a poor programming structure. We base our argument on our experience since 1993 in building distributed applications and mobile agent platforms. We have observed that every distributed applications contain three distinct aspects, which we call function, mobility and management. Separating an application into these three ... -
The Pesto project. Goals and motivation
(Research report; Forskningsrapport, 2001-06)Pesto is a storage system geared towards a computing model where private machines play a pivotal role. Sharing of data is crucial, both between partners, and between the many devices owned by individual users. Replication is the only sensible means to provide ubiquitous access to private data. However, without provisions, replication endangers privacy by enlarging the Trusted Computing Base. The ... -
The taste of Pesto
(Research report; Forskningsrapport, 2001-08)The Pesto distributed storage platform is geared towards a computing model where private machines play a pivotal r ˆ ole. We argue that no centralized solutions are acceptable in its design and that it supports allocation of separate tasks to separate system components found in its target environment. Hence, Pesto separates trust from responsibility, storage from access control policy, and ... -
Pesto flavoured security
(Research report; Forskningsrapport, 2002-05)Pesto aims at providing highly available and secure storage for longlived data to mobile users roaming into untrusted environments. Security in Pesto encompasses the following three aspects: availability, safety, and privacy. A mechanism supporting one aspect may adversely affect another. For example, replication may increase availability but complicates supporting confidentiality, and simply ... -
Using a virtual event space to understand parallel application communication behavior
(Research report; Forskningsrapport, 2003)We have developed EventSpace, a configurable data collecting, management and observation system for monitoring low-level synchronization and communication events with the purpose of understanding the behavior of parallel applications on clusters and multi-clusters. Applications are instrumented by adding data collecting code in the form of event collectors to an applications communication paths. ... -
Performance isolation and adaption in the Vortex Kernel
(Research report; Forskningsrapport, 2003-01-10)Vortex is a new multiprocessor operating system kernel intended for emerging Internet service applications. The architecture is based on SEDA's staged computational model. Vortex provides mechanisms for performance isolation and dynamic adaptation. Performance results validate that the resource control mechanisms of Vortex are effective, and that Vortex significantly outperforms Linux on single-threaded ... -
Some hints on the theory and practice of authentication in distributed systems
(Research report; Forskningsrapport, 2003-05-17)Authentication in Distributed Systems: Theory and Practice provides considerable insight. However, it can be hard to read, as many details are left out, probably for brevity; it is still 45 pages long. We provide detailed explanations of tricky points. -
Vortex. An event-driven multiprocessor operating system supporting performance isolation
(Research report; Forskningsrapport, 2003-06-13)Vortex is a new multiprocessor operating system that is entirely event-driven. The Vortex kernel, as well as its applications, are structured as stagesthat communicate through event passing. Each stage is a small finite state machine. The event architecture is efficient and allows Vortex to balance load across the processors automatically. Vortex uses an Event Scheduling Tree (EST) on each CPU. ... -
Using a waiting protocol to separate concerns in the mutual exclusion problem
(Research report; Forskningsrapport, 2003-11-21)How to implement process synchronization in a general-purpose software library while incurring a minimum of policy decisions on the system as a whole? We propose that in dealing with the problem of mutual exclusion in concurrent systems, a separation of concerns between the mechanism of detecting contention and the policy decision of what to do when such contention is detected is appropriate. We ... -
The Movitz development platform
(Research report; Forskningsrapport, 2003-12-19)We present a technical description of the Movitz development platform for stand-alone applications on the x86 PC architecture. -
Evaluating the performance of the allreduce collective operation on clusters. Approach and results
(Research report; Forskningsrapport, 2004)The performance of the collective operations provided by a communication library is important for many applications run on clusters. The communication structure of collective operations can be organized as a tree. Performance can be improved by configuring and mapping the tree to the clusters in use. We describe and demonstrate an approach for evaluating the performance of different configurations ... -
A programmable structure for pervasive computing
(Research report; Forskningsrapport, 2004)This exstended abstract presents an asymmetric and programmable (extensible) approach to pervasive computing. The idea is to off-load computations from light portable clients into a back-bone of seamlessly integrated servers. This way, a user can extend and personalize his pervasive computational environment by installing computations following his trajectory throughout the day. Focus on this extended ... -
ReflecTS: A reflective transaction service framework for open applications
(Research report; Forskningsrapport, 2004)Transactional middleware platforms must accommodate an increasingly diverse range of requirements from both applications and the underlying systems. It is clear that applications have characteristics and requirements that vary a lot, and that transactional middleware must be able to support the potential variety in transaction execution requirements. In this paper we describe ReflecTS, a reflective ... -
The last hop of global notification delivery to mobile users. Matching preferences, context, and device constraints.
(Research report; Forskningsrapport, 2004)Events injected by publishers into a publish/subscribe system may reach users through a variety of devices: a stationary desktop, a laptop, a mobile phone, etc. We argue that the "last hop" -- from the network to the output device -- has unique properties, owing to the mobile nature of these devices, and as such demands special consideration. In particular, user's preferences and location may limit ...
