In this paper, we argue that there is a need for an event-based middleware to build large-scale distributed systems. Existing publish/subscribe systems still have limitations compared to invocation-based middlewares. ...
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ISBN:
(纸本)0769515886
In this paper, we argue that there is a need for an event-based middleware to build large-scale distributed systems. Existing publish/subscribe systems still have limitations compared to invocation-based middlewares. We introduce Hermes, a novel event-based distributed middleware architecture that follows a type- and attribute-based publish/subscribe model. It centres around the notion of an event type and supports features commonly known from object-oriented languages like type hierarchies and super-type subscriptions. A scalable routing algorithm using an overlay routing network is presented that avoids global broadcasts by creating rendezvous nodes. Fault-tolerance mechanisms that can cope with different kinds of failures in the middleware are integrated with the routing algorithm resulting in a scalable and robust system.
In many Internet scale replicated system, not all replicas can be dealt with in the same way, since some will be in greater demand than others. In the case of weak consistency algorithms, we have observed that updatin...
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ISBN:
(纸本)0769515886
In many Internet scale replicated system, not all replicas can be dealt with in the same way, since some will be in greater demand than others. In the case of weak consistency algorithms, we have observed that updating first replicas having most demand a greater number of clients would gain access to updated content in a shorter period of time. In this work we have investigated the benefits that can be obtained by prioritizing replicas with greater demand, and considerable improvements have been achieved. In zones of higher demand, the consistent state is reached zip to six times quicker than with a normal weak consistency algorithm, without incurring the additional costs of the strong consistency.
In the last few years the event-based paradigm has been largely studied and considered as a promising approach to develop the communication infrastructure of distributed systems. It is particularly interesting when ea...
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The computing disciplines and the computing profession continue to appear gender segregated;despite limited progress, the number of women in computing still remains a minority. Differences persist at all levels, parti...
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The computing disciplines and the computing profession continue to appear gender segregated;despite limited progress, the number of women in computing still remains a minority. Differences persist at all levels, particularly when women attempt to reach higher levels of the corporate hierarchy. Today's social networking and friendly-computing provide an opportunity to redesign curricula to better engage young women in pursuing degrees and careers in computing. This may in turn increase participation and engagement and transform the study of computing from an isolated experience to an always-connected and socially-rich one.
The proceedings contain 32 papers. The topics discussed include: secure conflict-free replicated data types;P4Fuzz: compiler fuzzer for dependable programmable dataplanes;gathering with a strong team in weakly byzanti...
ISBN:
(纸本)9781450389334
The proceedings contain 32 papers. The topics discussed include: secure conflict-free replicated data types;P4Fuzz: compiler fuzzer for dependable programmable dataplanes;gathering with a strong team in weakly byzantine environments;communication costs in a geometric communication network;certification of an exact worst-case self-stabilization time;arbitrary pattern formation on infinite regular tessellation graphs;optimal exclusive perpetual grid exploration by luminous myopic opaque robots with common chirality;bio-inspired energy distribution for programmable matter;performance analysis of a distributed algorithm for admission control in wireless networks under the 2-hop interference model;and node classification and geographical analysis of the lightning cryptocurrency network.
We consider the following forms of mobile interactions: client/server interactions, whereby the request of a client triggers the execution of a unit of code in a server and returns the results to the client;remote eva...
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The publish/subscribe communication model is increasingly considered for implementing middleware infrastructures for widely distributed applications. Scalability issues and routing algorithms of such systems have rece...
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ISBN:
(纸本)0769515886
The publish/subscribe communication model is increasingly considered for implementing middleware infrastructures for widely distributed applications. Scalability issues and routing algorithms of such systems have recently been the focus of intensive research. So far little attention has been given to security and management issues. In current publish/subscribe systems, malicious publishers can very easily insert bogus notifications which may propagated to a large number of subscribers. Moreover, there is no method to control what notifications the subscribers are authorized to receive. We describe a method to specify access control policy rules using expressions similar to subscription expressions. These policies define access rules for publish and subscribe functions and screening rules for notifications.
This work presents an infrastructure that simplifies the development of distributed applications that can adapt automatically to nonfunctional properties of their components and of their execution environment. This in...
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ISBN:
(纸本)0769515886
This work presents an infrastructure that simplifies the development of distributed applications that can adapt automatically to nonfunctional properties of their components and of their execution environment. This infrastructure, based on the programming language Lua and on CORBA, allows applications to select dynamically the components that best suit their requirements, to verify whether the system is satisfying these requirements, and to react, when appropriate, to variations in the nonfunctional properties of the services in use. We use CORBA's Trading Service to support dynamic component selection. An extensible monitoring facility supports monitoring of dynamically defined requirements. We use the Lua language to specify adaptation strategies, and a smart proxy mechanism to apply these strategies.
In this work we propose an architecture for distributed multimedia applications based on an event-driven programming model. To avoid the synchronization problems inherent to multi-threaded programming, the proposed ar...
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ISBN:
(纸本)0769515886
In this work we propose an architecture for distributed multimedia applications based on an event-driven programming model. To avoid the synchronization problems inherent to multi-threaded programming, the proposed architecture is based on a single-threaded structure. Instead of multi-threading, we opted for the event-oriented approach allied to multiple communication channels with user-defined handling procedures to allow the application to deal concurrently with control and data streams. We discuss this programming model, present the system we have implemented based on this model, and describe the experience we have had with this system.
The fundamental paradigm of context-aware computing has lead to a diversity of conceivable context-based applications. In order to support these applications, efficient and scalable context management platforms have b...
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ISBN:
(纸本)9781424442331
The fundamental paradigm of context-aware computing has lead to a diversity of conceivable context-based applications. In order to support these applications, efficient and scalable context management platforms have become utterly important. In this paper we propose a layered reference model that encapsulates suitable abstractions to tackle the complexity of context management in mobile ad-hoc networks. For each layer we outline strategies and mechanisms we have developed to manage context information efficiently so that it can readily be used by context-based services and applications in these networks. In addition, we discuss refinements of the current model that we currently investigate, which are related to data semantics such as context quality and expressive location models, performance enhancement by adaptation, and aspects regarding the integration of ad-hoc context management with infrastructure-based systems leading to a hybrid system structure.
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