English
norskInstitutt for informatikk: Recent submissions
Now showing items 601-620 of 640
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The StormCast API. Specification of software interfaces in StormCast 2.1
(Research report; Forskningsrapport, 1994-12)This report presents the software architecture in the StormCast meteorological workbench. The focus is on the software interfaces in StormCast version 2.1. For each layer in the architecture the functionality, the call structure, the interfaces, the event diagrams and test data are described. In addition, further works are discussed. The identication of software interfaces are based on the StormCast ... -
Policies and metrics for fair resource sharing
(Research report; Forskningsrapport, 2006)Performance isolation is essential to operating systems shared by dependable services. Unfortunately, most such systems, including real-time operating systems and VMMs, only fairly divide and account for CPU cycles. We submit that dependable services require specifying and enforcing policies for all resources, and that current metrics for evaluating fair sharing are insufficient. This paper proposes ... -
A graphical deployment and management tool for distributed applications
(Research report; Forskningsrapport, 2005)OOPP is a component based middleware platform with support for complex distributed applications. The main goal of OOPP is to create an expressive programming model for distributed applications where by default details are hidden for the programmer. When necessary, reflection is used to expose and sometimes modify these details. All interaction with an OOPP component are specified by its component ... -
Secure communication in FRTP
(Research report; Forskningsrapport, 1995-02)To ensure privacy, users of the File Repository Transfer Protocol (Frtp) may require that communication partners are properly authenticated. If one partner wants the communication to be crypted, the other must honor the request. This report describes how authentication and privacy are realized. It is shown, by means of an authentication logic, that the protocol achives its goal in this respect. -
Practical and low-overhead masking of failures of TCP-based servers
(Research report; Forskningsrapport, 2005-08-25)This article describes an architecture that allows a replicated service to survive crashes without breaking its TCP connections. Our approach does not require modifications to the TCP protocol, to the operating system on the server, or to any of the software running on the clients. Furthermore, it runs on commodity hardware. We compare two implementations of this architecture – one based on ... -
File repository transfer protocol. Version 1
(Research report; Forskningsrapport, 1995-02)This document presents and specifies the protocol that interfaces clients and servers in the File Repository (FR). The FR is a software system that supports sharing of files. The protocol is modelled after Smtp and Nntp and is encoded in Ascii. No details of server implementation is visible in the protocol description, but we state our intentions at several occasions. -
Minimizing unwanted traffic in a global messaging system. Spam, denial-of-service-attacks, and edacious subscribers
(Research report; Forskningsrapport, 2005)The main purpose of this paper is to illuminate two types of unwanted traffic in a publish/subscribe system -- malicious (spam, DoS attacks) and vain (unused events) -- and suggest a general mechanism for minimizing their effects. We do this by augmenting the classic publish/subscribe interface with volume-limiting parameters -- a combination of attributes assigned to events by publishers and ... -
Engineering push-based web services
(Research report; Forskningsrapport, 2005)Much of the content of popular Internet information sources is highly dynamic: urgent in nature and sometimes relevant only for a short time. The typical approach to querying such dynamic sources is polling for updates often.1 This strains the traditional pull-based Internet and wastes network resources on transmitting redundant information. This paper focuses on how to structure the Internet to ... -
Performance experiments with the Storm View Distributed Parallel Volume Renderer.
(Research report; Forskningsrapport, 1995-06)Volume rendering is a useful but cpu-intensive method for visualizing large scalar fields. The time to render a single image may be reduced by parallel processing. This paper reports on performance experiments with the StormView volume renderer, which is parallelized on a set of 57 MIPS / 17 MFLOPS workstations connected by a 10 Mbps Ethernet. For certain user patterns, we show that our parallelization ... -
A Declarative Profile Model for Qos negotiation
(Research report; Forskningsrapport, 2005-12)In this report we define the semantics of a language for dynamic QoS expressions which can be evaluated at run-time for conformance. We define how expressions can be constructed from atomic expressions termed ’basic profiles’ using composition operators. Two such operators are defined: The sum ( ’+’ ) which corresponds to simple conjunction and component-sum (’Å’) which assume that the operands ... -
An introduction to the TACOMA distributed system. Version 1.0
(Research report; Forskningsrapport, 1995-06)This report briefly introduces TACOMA Version 1.0. This distributed system supports agents, computations that can roam the internet. The report presents the TACOMA project, the computational model, how to get started, and the basic TACOMA abstractions. -
The Longcut Wide Area Network Emulator. Design and Evaluation
(Research report; Forskningsrapport, 2005)Experiments run on a Grid, consisting of clusters administered by multiple organizations connected by shared wide area networks (WANs), may not be reproducible. First, traffic on the WAN cannot be controlled. Second, allocating the same resources for subsequent experiments can be difficult. Longcut solves both problems by splitting a single cluster into several parts, and for each part having one ... -
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 ... -
Efficient bill-of-materials algorithms
(Research report; Forskningsrapport, 1996-09-01)It has been shown that every linearly recursive database query can be expressed as a transitive closure possibly preceded and followed by relational algebraic operations. A large class of such queries computes the bill-of-materials of database relations. This paper presents efficient sequential and distributed algorithms that compute the bill-of-materials of a database relation. These algorithms ... -
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 ... -
Security in the PASTA project
(Research report; Forskningsrapport, 1997-02-04)This paper presents the system model for the work on security in the Pasta project. We present the objectives of the security effort, the threats we will consider, and those we will not consider. As such, the paper describes the environment which applications must be prepared to face, and still provide users with the desired degree of privacy. -
Environment mobility. Moving the desktop around.
(Research report; Forskningsrapport, 2004)In this position paper, we focus on issues related to middleware support for software mobility in ad hoc and pervasive systems. In particular, we are interested in moving the computational environment of a mobile user following his trajectory. We present details of WAIFARER, a prototype implementation that automatically saves and restores application level state to support this mobility. Security, ... -
On the design and performance of the PARFUM Parallel Fault Tolerant Volume Renderer
(Research report; Forskningsrapport, 1997-01)Volume rendering is an important and CPU-intensive technique for visualizing large scalar fields. In essence, a volume renderer performs two activites on behalf of the user: loading a new data set, and rendering the current one. At one level, the performance of an individual activity is important. At another level, the erformance of the session as a whole, in particular switching from one activity ... -
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 ... -
QoS applied to security in mobile computing
(Research report; Forskningsrapport, 1997-06-30)Hand-held mobile computers have the potential to become important communication tools for roaming users. As such, they will also become very personal. They will be used under a wide range of operating conditions, and tight user control will be enforced on issues like power consumption, consistency control, and trust management. Their ability to adapt will be the key to their success. In this paper ...
