Voici les éléments 1 - 9 sur 9
  • Publication
    Métadonnées seulement
    Exploiting Concurrency in Domain-Specific Data Structures: A Concurrent Order Book and Workload Generator for Online Trading
    Concurrent programming is essential to exploit parallel processing capabilities of modern multi-core CPUs. While there exist many languages and tools to simplify the development of concurrent programs, they are not always readily applicable to domain-specific problems that rely on complex shared data structures associated with various semantics (e.g., priorities or consistency). In this paper, we explore such a domain-specific application from the financial field, where a data structure—an order book —is used to store and match orders from buyers and sellers arriving at a high rate. This application has interesting characteristics as it exhibits some clear potential for parallelism, but at the same time it is relatively complex and must meet some strict guarantees, notably w.r.t. the ordering of operations. We first present an accurate yet slightly simplified description of the order book problem and describe the challenges in paral- lelizing it. We then introduce several approaches for introducing concurrency in the shared data structure, in increasing order of sophistication starting from lock-based techniques to partially lock-free designs. We propose a comprehensive workload generator for constructing histories of orders according to realistic models from the financial domain. We finally perform an evaluation and comparison of the different concurrent designs.
  • Publication
    Métadonnées seulement
    Confidentiality-Preserving Publish/Subscribe: A Survey
    Publish/subscribe (pub/sub) is an attractive communication paradigm for large-scale distributed applications running across multiple administrative domains. Pub/sub allows event-based information dissemination based on constraints on the nature of the data rather than on pre-established communication channels. It is a natural fit for deployment in untrusted environments such as public clouds linking applications across multiple sites. However, pub/sub in untrusted environments leads to major confidentiality concerns stemming from the content-centric nature of the communications. This survey classifies and analyzes different approaches to confidentiality preservation for pub/sub, from applications of trust and access control models to novel encryption techniques. It provides an overview of the current challenges posed by confidentiality concerns and points to future research directions in this promising field.
  • Publication
    Métadonnées seulement
    Performance/Security Tradeoffs for Content-Based Routing Supported by Bloom Filters
    Content-based routing is widely used in large-scale distribu-ted systems as it provides a loosely-coupled yet expressive form of communication: consumers of information register their interests by the means of subscriptions, which are subsequently used to determine the set of recipients of every message published in the system. A major challenge of content-based routing is security. Although some techniques have been proposed to perform matching of encrypted subscriptions against encrypted messages, their computational cost is very high. To speed up that process, it was recently proposed to embed Bloom filters in both subscriptions and messages to reduce the space of subscriptions that need to be tested. In this article, we provide a comprehensive analysis of the information leaked by Bloom filters when implementing such a “prefiltering” strategy. The main result is that although there is a fundamental trade-off between prefiltering efficiency and information leakage, it is practically possible to obtain good prefiltering while securing the scheme against leakages with some simple randomization techniques.
  • Publication
    Métadonnées seulement
    StreamHub: A Massively Parallel Architecture for High-Performance Content-Based Publish/Subscribe
    By routing messages based on their content, publish/subscribe (pub/sub) systems remove the need to establish and maintain fixed communication channels. Pub/sub is a natural candidate for designing large-scale systems, composed of applications running in different domains and communicating via middleware solutions deployed on a public cloud. Such pub/sub systems must provide high throughput, filtering thousands of publications per second matched against hundreds of thousands of registered subscriptions with low and predictable delays, and must scale horizontally and vertically. As large-scale application composition may require complex publications and subscriptions representations, pub/sub system designs should not rely on the specific characteristics of a particular filtering scheme for implementing scalability. In this paper, we depart from the use of broker overlays, where each server must support the whole range of operations of a pub/sub service, as well as overlay management and routing functionality. We propose instead a novel and pragmatic tiered approach to obtain high-throughput and scalable pub/sub for clusters and cloud deployments. We separate the three operations involved in pub/sub and leverage their natural potential for parallelization. Our design, named StreamHub, is oblivious to the semantics of subscriptions and publications. It can support any type and number of filtering operations implemented by independent libraries. Experiments on a cluster with up to 384 cores indicate that StreamHub is able to register 150 K subscriptions per second and filter next to 2 K publications against 100 K stored subscriptions, resulting in nearly 400 K notifications sent per second. Comparisons against a broker overlay solution shows an improvement of two orders of magnitude in throughput when using the same number of cores.
  • Publication
    Métadonnées seulement
    Infrastructure Provisioning for Scalable Content-based Routing: Framework and Analysis
    Content-based publish/subscribe is an attractive paradigm for designing large-scale systems, as it decouples producers of information from consumers. This provides extensive flexibility for applications, which can use a modular architecture. Using this architecture, each participant expresses its interest in events by means of filters on the content of those events instead of using pre-established communication channels. However, matching events against filters has a non-negligible processing cost. Scaling the infrastructure with the number of users or events requires appropriate provisioning of resources for each of the operations involved: routing and filtering. In this paper, we propose and describe a generic, modular, and scalable infrastructure for supporting high-performance content-based publish/subscribe. We analyze its properties and show how it dynamically scales in a realistic setting. Our results provide valuable insights into the design and deployment of scalable content-based routing infrastructures.
  • Publication
    Métadonnées seulement
    Efficient Key Updates through Subscription Re-encryption for Privacy-Preserving Publish/Subscribe
    Content-based publish/subscribe (pub/sub) is an appealing information dissemination paradigm for distributed systems. Consumers of data subscribe to a pub/sub service, typically offered through a distributed broker overlay, and indicate their interests as constraints over the information content. Publishers generate the information flow, which the brokers filter and route to the interested subscribers. Protecting the information confidentiality, and in particular the interests of subscribers, is an important concern when brokers are located in untrusted domains such as public clouds. Encrypted matching techniques allow untrusted brokers to store encrypted subscriptions and match them against encrypted publications. Updates of encryption keys regularly happen in such contexts due to changes in trust relations. These key updates cause the invalidation of stored encrypted subscriptions and force subscribers to re-encrypt and re-submit them. This long and costly operation impacts the pub/sub service continuity and performance. In this paper, we propose a novel technique that allows updating encrypted subscriptions directly at the brokers while maintaining privacy guarantees. We present an implementation of the technique for the ASPE encrypted matching scheme and prove the security of our extension. We evaluate its practical effectiveness through a prototype implementation including a dependable key dis- tribution protocol. Our experiments show the ability to handle key updates while preserving service continuity and performance.
  • Publication
    Métadonnées seulement
    Efficient and Confidentiality-Preserving Content-Based Publish/Subscribe with Prefiltering
    Content-based publish/subscribe provides a loosely-coupled and expressive form of communication for large-scale distributed systems. Confidentiality is a major challenge for publish/subscribe middleware deployed over multiple administrative domains. Encrypted matching allows confidentiality-preserving content-based filtering but has high performance overheads. It may also prevent the use of classical optimizations based on subscriptions containment. We propose a support mechanism that reduces the cost of encrypted matching, in the form of a prefiltering operator using Bloom filters and simple randomization techniques. This operator greatly reduces the amount of encrypted subscriptions that must be matched against incoming encrypted publications. It leverages subscription containment information when available, but also ensures that containment confidentiality is preserved otherwise. We propose containment obfuscation techniques and provide a rigorous security analysis of the information leaked by Bloom filters in this case. We conduct a thorough experimental evaluation of prefiltering under a large variety of workloads. Our results indicate that prefiltering is successful at reducing the space of subscriptions to be tested in all cases. We show that while there is a tradeoff between prefiltering efficiency and information leakage when using containment obfuscation, it is practically possible to obtain good prefiltering performance while securing the technique against potential leakages.
  • Publication
    Métadonnées seulement
    Elastic Scaling of a High-Throughput Content-Based Publish/Subscribe Engine
    (: IEEE, 2014-6-30) ;
    Heinze, Thomas
    ;
    Martin, André
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    ; ;
    Fetzer, Christof
    ;
    Jerzak, Zbigniew
    ;
    ;
    Publish/subscribe (pub/sub) infrastructures running as a service on cloud environments offer simplicity and flexibility for composing distributed applications. Provisioning them appropriately is however challenging. The amount of stored subscriptions and incoming publications varies over time, and the computational cost depends on the nature of the applications and in particular on the filtering operation they require (e.g., content-based vs. topic-based, encrypted vs. non-encrypted filtering). The ability to elastically adapt the amount of resources required to sustain given throughput and delay requirements is key to achieving cost-effectiveness for a pub/sub service running in a cloud environment. In this paper, we present the design and evaluation of an elastic content-based pub/sub system: E-STREAMHUB. Specific contributions of this paper include: (1) a mechanism for dynamic scaling, both out and in, of stateful and stateless pub/sub operators, (2) a local and global elasticity policy enforcer maintaining high system utilization and stable end-to-end latencies, and (3) an evaluation using real-world tick workload from the Frankfurt Stock Exchange and encrypted content-based filtering.
  • Publication
    Métadonnées seulement
    Thrifty Privacy: Efficient Support for Privacy-Preserving Publish/Subscribe
    Content-based publish/subscribe is an appealing paradigm for building large-scale distributed applications. Such applications are often deployed over multiple administrative domains, some of which may not be trusted. Recent attacks in public clouds indicate that a major concern in untrusted domains is the enforcement of privacy. By routing data based on subscriptions evaluated on the content of publications, publish/subscribe systems can expose critical information to unauthorized parties. Information leakage can be avoided by the means of privacy-preserving filtering, which is supported by several mechanisms for encrypted matching. Unfortunately, all existing approaches have in common a high performance overhead and the difficulty to use classical optimization for content-based filtering such as per-attribute containment. In this paper, we propose a novel mechanism that greatly reduces the cost of supporting privacy-preserving filtering based on encrypted matching operators. It is based on a pre-filtering stage that can be combined with containment graphs, if available. Our experiments indicate that pre-filtering is able to significantly reduce the number of encrypted matching for a variety of workloads, and therefore the costs associated with the cryptographic mechanisms. Furthermore, our analysis shows that the additional data structures used for pre-filtering have very limited impact on the effectiveness of privacy preservation.