The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Sangyoon Oh - One of the best experts on this subject based on the ideXlab platform.
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real time performance analysis for publish Subscribe systems
Future Generation Computer Systems, 2010Co-Authors: Sangyoon OhAbstract:The publish/Subscribe communication system has been a popular communication model in many areas. Especially, it is well suited for a distributed real-time system in many ways. However, the research of cost model and analysis of publish/Subscribe system in a distributed real-time system have not been suggested yet. In this paper, we present our cost model for publish/Subscribe system in a real-time domain, analyze its performance, and compare it with other communication models such as request/reply and polling models. Our empirical result on mobile embedded device shows accordance with cost analysis, which verifies correctness and usefulness of our cost model.
Gero Muhl - One of the best experts on this subject based on the ideXlab platform.
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on quality of service and publish Subscribe
International Conference on Distributed Computing Systems Workshops, 2006Co-Authors: Stefan Behnel, Ludger Fiege, Gero MuhlAbstract:Publish-Subscribe is a powerful paradigm for distributed communication based on decoupled producers and consumers of information. Its event-driven nature makes it very appealing for large-scale data dissemination infrastructures. Various architectures were proposed in recent years that provide very diverse features. However, there are few well-defined metrics in the publish-Subscribe area that would allow their evaluation and comparison. In this paper, we provide a broad overview of relevant quality-of-service metrics and describe their specific meaning in the context of distributed and decentralized publish-Subscribe systems. Our goal is to provide a common base for future evaluations of emerging systems and for the design of qualityof- service aware publish-Subscribe infrastructures.
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large scale content based publish Subscribe systems
2002Co-Authors: Gero MuhlAbstract:Today, the architecture of distributed computer systems is dominated by client/server platforms relying on synchronous request/reply. This architecture is not well suited to implement information-driven applications like news delivery, stock quoting, air traffic control, and dissemination of auction bids due to the inherent mismatch between the demands of these applications and the characteristics of those platforms. In contrast to that, publish/Subscribe directly reflects the intrinsic behavior of information-driven applications because communication here is indirect and initiated by producers of information: Producers publish notifications and these are delivered to Subscribed consumers by the help of a notification service that decouples the producers and the consumers. Therefore, publish/Subscribe should be the first choice for implementing such applications. The expressiveness of the notification selection mechanism used by the consumers to describe the notifications they are interested in is crucial for the flexibility of a notification service. Content-based notification selection is most expressive because it allows to evaluate filter predicates over the whole content of a notification. The advantage in expressiveness compared to channel- or subject-based selection results in increased flexibility facilitating extensibility and change. On the other hand, scalable implementations of content-based notification services are difficult to realize. Indeed, the expressiveness of notification selection must be carefully chosen in large-scale systems, because expressiveness and scalability are interdependent. Hence, the most fundamental problem in the area of content-based publish/Subscribe systems is probably the scalable routing of notifications from their producers to their respective consumers. Unfortunately, existing content-based notification services are not mature enough to be used in large-scale, widely-distributed environments. Most existing notification services are either centralized, use flooding, or use simple routing algorithms that assume that each event broker has global knowledge about all active subscriptions. All these approaches exhibit severe scalability problems in large-scale systems. In contrast to that, this thesis concentrates on mechanisms to improve the scalability of content-based routing algorithms and presents more advanced routing algorithms that do not rely on global knowledge. The algorithms presented here exploit similarities between subscriptions by using identity- and covering-tests, and by merging filters. While identity-based routing is a simplified version of covering-based routing, merging-based routing is more advanced because it exploits the concept of filter merging. Furthermore, the idea of imperfect routing algorithms is introduced. The thesis consists of a theoretical and a practical part. The theoretical part presents a formal specification of publish/Subscribe systems, a routing framework and a set of routing algorithms, and discusses how the routing optimizations can be broken down to the actual data/filter model. The practical part presents the implementation of the Rebeca notification service which supports advertisements and all the routing algorithms mentioned above. A detailed practical evaluation of the implemented algorithms based upon the prototype is also presented.
Kurt Rothermel - One of the best experts on this subject based on the ideXlab platform.
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pleroma a sdn based high performance publish Subscribe middleware
International Middleware Conference, 2014Co-Authors: Muhammad Adnan Tariq, Boris Koldehofe, Sukanya Bhowmik, Kurt RothermelAbstract:With the increasing popularity of Software-defined networks (SDN), TCAM memory of switches can be directly accessed by a publish/Subscribe middleware to perform filtering operations at low latency. This way two important requirements for a publish/Subscribe middleware can be fulfilled: namely bandwidth efficiency and line-rate performance in forwarding messages between producers and consumers. Nevertheless, it is challenging to sustain line-rate performance in the presence of dynamic changes in the interest of producers and consumers. In this paper, we propose and evaluate the PLEROMA middleware to realize publish/Subscribe at line-rate and bandwidth efficiently in SDN. PLEROMA offers methods to efficiently reconfigure a deployed topology in the presence of dynamic subscriptions and advertisements. Furthermore, PLEROMA ensures interoperability and independent reconfiguration of multiple controlled SDN networks.
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securing broker less publish Subscribe systems using identity based encryption
IEEE Transactions on Parallel and Distributed Systems, 2014Co-Authors: Muhammad Adnan Tariq, Boris Koldehofe, Kurt RothermelAbstract:The provisioning of basic security mechanisms such as authentication and confidentiality is highly challenging in a content-based publish/Subscribe system. Authentication of publishers and Subscribers is difficult to achieve due to the loose coupling of publishers and Subscribers. Likewise, confidentiality of events and subscriptions conflicts with content-based routing. This paper presents a novel approach to provide confidentiality and authentication in a broker-less content-based publish/Subscribe system. The authentication of publishers and Subscribers as well as confidentiality of events is ensured, by adapting the pairing-based cryptography mechanisms, to the needs of a publish/Subscribe system. Furthermore, an algorithm to cluster Subscribers according to their subscriptions preserves a weak notion of subscription confidentiality. In addition to our previous work , this paper contributes 1) use of searchable encryption to enable efficient routing of encrypted events, 2) multicredential routing a new event dissemination strategy to strengthen the weak subscription confidentiality, and 3) thorough analysis of different attacks on subscription confidentiality. The overall approach provides fine-grained key management and the cost for encryption, decryption, and routing is in the order of Subscribed attributes. Moreover, the evaluations show that providing security is affordable w.r.t. 1) throughput of the proposed cryptographic primitives, and 2) delays incurred during the construction of the publish/Subscribe overlay and the event dissemination.
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meeting Subscriber defined qos constraints in publish Subscribe systems
Concurrency and Computation: Practice and Experience, 2011Co-Authors: Muhammad Adnan Tariq, Boris Koldehofe, Gerald G Koch, Imran Khan, Kurt RothermelAbstract:Current distributed publish/Subscribe systems consider all participants to have similar QoS requirements and contribute equally to the system's resources. However, in many real-world applications, the message delay tolerance of individual participants may differ widely. Disseminating messages according to individual delay requirements not only allows for the satisfaction of user-specific needs, but also significantly improves the utilization of the resources that participants contribute to a publish/Subscribe system. In this article, we propose a peer-to-peer-based approach to satisfy the individual delay requirements of Subscribers in the presence of bandwidth constraints. Our approach allows Subscribers to dynamically adjust the granularity of their subscriptions according to their bandwidth constraints and delay requirements. Subscribers maintain the overlay in a decentralized manner, exclusively establishing connections that satisfy their individual delay requirements, and that provide messages exactly meeting their subscription granularity. The evaluations show that for many practical workloads, the proposed publish/Subscribe system can scale up to a large number of Subscribers and performs robustly in a very dynamic setting. Copyright © 2011 John Wiley & Sons, Ltd. (Spatial indexing can work with any ordered data type with a known domain [5]. Evaluation results are not sensitive to the choice of data type and therefore, similar to [5] only integer data types are considered.)
Emin Gun Sirer - One of the best experts on this subject based on the ideXlab platform.
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corona a high performance publish Subscribe system for the world wide web
Networked Systems Design and Implementation, 2006Co-Authors: Venugopalan Ramasubramanian, Ryan Peterson, Emin Gun SirerAbstract:Despite the abundance of frequently changing information, the Web lacks a publish-Subscribe interface for delivering updates to clients. The use of naive polling for detecting updates leads to poor performance and limited scalability as clients do not detect updates quickly and servers face high loads imposed by active polling. This paper describes a novel publish-Subscribe system for the Web called Corona, which provides high performance and scalability through optimal resource allocation. Users register interest in Web pages through existing instant messaging services. Corona monitors the Subscribed Web pages, detects updates efficiently by allocating polling load among cooperating peers, and disseminates updates quickly to users. Allocation of resources for polling is driven by a distributed optimization engine that achieves the best update performance without exceeding load limits on content servers. Large-scale simulations and measurements from PlanetLab deployment demonstrate that Corona achieves orders of magnitude improvement in update performance at a modest cost.
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client behavior and feed characteristics of rss a publish Subscribe system for web micronews
Internet Measurement Conference, 2005Co-Authors: Hongzhou Liu, Venugopalan Ramasubramanian, Emin Gun SirerAbstract:While publish-Subscribe systems have attracted much research interest since the last decade, few established benchmarks have emerged, and there has been little characterization of how publish-Subscribe systems are used in practice. This paper examines RSS, a newly emerging, widely used publish-Subscribe system for Web micronews. Based on a trace study spanning 45 days at a medium-size academic department and periodic polling of approximately 100,000 RSS feeds, we extract characteristics of RSS content and usage. We find that RSS workload resembles the Web in content size and popularity; feeds are typically small (less than 10KB), albeit with a heavy tail, and feed popularity follows a power law distribution. The update rate of RSS feeds is widely distributed; 55% of RSS feeds are updated hourly, while 25% show no updates for several days. And, only small portions of RSS content typically change during an update; 64% of updates involve less than three lines of the RSS content. Overall, this paper presents an analysis of RSS, the first widely deployed publish-Subscribe system, and provides insights for the design of next generation publish-Subscribe systems.
Alberto Coenporisini - One of the best experts on this subject based on the ideXlab platform.
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aups an open source authenticated publish Subscribe system for the internet of things
Information Systems, 2016Co-Authors: Alessandra Rizzardi, Sabrina Sicari, Daniele Miorandi, Alberto CoenporisiniAbstract:Abstract The arising of the Internet of Things (IoT) is enabling new service provisioning paradigms, able to leverage heterogeneous devices and communication technologies. Efficient and secure communication mechanisms represent a key enabler for the wider adoption and diffusion of IoT systems. One of the most widely employed protocols in IoT and machine-to-machine communications is the Message Queue Telemetry Transport (MQTT), a lightweight publish/Subscribe messaging protocol designed for working with constrained devices. In MQTT messages are assigned to a specific topic to which users can Subscribe. MQTT presents limited security support. In this paper we present a secure publish/Subscribe system extending MQTT by means of a key management framework and a policy enforcement one. In this way the flow of information in MQTT-powered IoT systems can be flexibly controlled by means of flexible policies. The solution presented is released as open source under Apache v.2 license.
