Imperial College London

ProfessorAlexanderWolf

Faculty of EngineeringDepartment of Computing

Visiting Professor
 
 
 
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Contact

 

+44 (0)20 7594 8211a.wolf Website

 
 
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Assistant

 

Mr Sam Hesketh +44 (0)20 7594 8303

 
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Location

 

569Huxley BuildingSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

115 results found

Novotny P, Ko B-J, Wolf AL, 2018, Locating faults in MANET-hosted software systems, IEEE Transactions on Dependable and Secure Systems, Vol: 15, Pages: 452-465, ISSN: 1545-5971

We present a method to locate faults in service-based software systems hosted on mobile ad hoc networks (MANETs). Insuch systems, computations are structured as interdependent services distributed across the network, collaborating to satisfy clientrequests. Faults, which may occur at either or both the service and network layers, propagate by cascading through some subset of theservices, from their root causes back to the clients that initiate requests. Fault localization in this environment is especially challengingbecause the systems are typically subject to a wider variety and higher incidence of faults than those deployed in fixed networks, theresources available to collect and store analysis data are severely limited, and many of the sources of faults are by their naturetransient. Our method makes use of service-dependence and fault data that are harvested in the network through decentralized,run-time observations of service interactions and fault symptoms. We have designed timing- and Bayesian-based reasoningtechniques to analyze the data in the context of a specific fault propagation model. The analysis provides a ranked list of candidate faultlocations. Through extensive simulations, we evaluate the performance of our method in terms of its accuracy in correctly ranking rootcauses under a wide range of operational conditions.

JOURNAL ARTICLE

Pietzuch PR, Koliousis A, Weidlich M, Costa P, Wolf A, Castro Fernandez Ret al., 2016, Demo- The SABER system for window-based hybrid stream processing with GPGPUs, DEBS 2016, Publisher: Association for Computing Machinery, Pages: 354-357

Heterogeneous architectures that combine multi-core CPUs withmany-core GPGPUs have the potential to improve the performanceof data-intensive stream processing applications. Yet, a stream pro-cessing engine must execute streaming SQL queries with sufficientdata-parallelism to fully utilise the available heterogeneous proces-sors, and decide how to use each processor in the most effectiveway. Addressing these challenges, we demonstrate SABER, ahybrid high-performance relational stream processing engine forCPUs and GPGPUs. SABER executes window-based streaming SQL queries in a data-parallel fashion and employs an adaptive scheduling strategy to balance the load on the different types of processors. To hidedata movement costs, SABER pipelines the transfer of stream databetween CPU and GPGPU memory. In this paper, we review thedesign principles of SABER in terms of its hybrid stream processingmodel and its architecture for query execution. We also present aweb front-end that monitors processing throughput.

CONFERENCE PAPER

Koliousis A, Weidlich M, Fernandez R, Wolf A, Costa P, Pietzuch Pet al., 2016, Saber: Window-based Hybrid Stream Processing for Heterogeneous Architectures, 2016 ACM SIGMOD/PODS Conference, Publisher: ACM

Modern servers have become heterogeneous, often combining multicoreCPUs with many-core GPGPUs. Such heterogeneous architectureshave the potential to improve the performance of data-intensivestream processing applications, but they are not supported by currentrelational stream processing engines. For an engine to exploit aheterogeneous architecture, it must execute streaming SQL querieswith sufficient data-parallelism to fully utilise all available heterogeneousprocessors, and decide how to use each in the most effectiveway. It must do this while respecting the semantics of streamingSQL queries, in particular with regard to window handling.We describe SABER, a hybrid high-performance relational streamprocessing engine for CPUs and GPGPUs. SABER executes windowbasedstreaming SQL queries in a data-parallel fashion using allavailable CPU and GPGPU cores. Instead of statically assigningquery operators to heterogeneous processors, SABER employs anew adaptive heterogeneous lookahead scheduling strategy, whichincreases the share of queries executing on the processor that yieldsthe highest performance. To hide data movement costs, SABERpipelines the transfer of stream data between different memory typesand the CPU/GPGPU. Our experimental comparison against state-ofthe-artengines shows that SABER increases processing throughputwhile maintaining low latency for a wide range of streaming SQLqueries with small and large windows sizes.

CONFERENCE PAPER

Wolf AL, 2016, Moving Forward, Communications of the ACM, Vol: 59, Pages: 5-5, ISSN: 0001-0782

JOURNAL ARTICLE

Wolf AL, 2015, A New Chief Executive Officer and Executive Director of ACM, COMMUNICATIONS OF THE ACM, Vol: 58, Pages: 4-5, ISSN: 0001-0782

JOURNAL ARTICLE

Novotny P, Ko BJ, Wolf AL, 2015, On-Demand Discovery of Software Service Dependencies in MANETs, IEEE TRANSACTIONS ON NETWORK AND SERVICE MANAGEMENT, Vol: 12, Pages: 278-292, ISSN: 1932-4537

JOURNAL ARTICLE

Pamboris A, Báguena M, Wolf AL, Manzoni P, Pietzuch Pet al., 2015, Demo: NOMAD: an edge cloud platform for hyper-responsive mobile apps, 13th Annual International Conference on Mobile Systems, Applications, and Services (MobiSys 2015), Publisher: Association for Computing Machinery, Pages: 459-459

CONFERENCE PAPER

Novotny P, Ko BJ, Wolf AL, 2015, Delay Tolerant Harvesting of Monitoring Data for MANET-Hosted Service-Based Systems, 12th IEEE International Conference on Services Computing (SCC), Publisher: IEEE, Pages: 9-16

CONFERENCE PAPER

Silvestri S, Holbert B, Novotny P, La Porta T, Wolf A, Swami Aet al., 2015, Inferring Network Topologies in MANETs Applied to Service Redeployment, International Conference on Computer Communications and Networks ICCCN, Publisher: IEEE, ISSN: 1095-2055

CONFERENCE PAPER

Novotny P, Urgaonkar R, Wolf AL, Ko Bet al., 2015, Dynamic Placement of Composite Software Services in Hybrid Wireless Networks, 34th IEEE Annual Military Communications Conference (MILCOM) on Leveraging Technology - The Joint Imperative, Publisher: IEEE, Pages: 1052-1057, ISSN: 2155-7578

CONFERENCE PAPER

Foukas X, Carzaniga A, Wolf AL, 2015, Measuring the Mixing Time of a Network, 34th IEEE Conference on Computer Communications (INFOCOM), Publisher: IEEE, ISSN: 0743-166X

CONFERENCE PAPER

Pietzuch PR, Mai L, Rupprecht L, Alim A, Costa P, Migliavacca M, Pietzuch P, Wolf Aet al., 2014, NetAgg: Middleboxes for Application-Specific Traffic Aggregation, 10th International Conference on Emerging Networking Experiments and Technologies (CoNEXT), Publisher: ACM, Pages: 249-262

CONFERENCE PAPER

Carzaniga A, Wolf AL, IEEE Conference on Computer Communications (INFOCOM), IEEE Conference on Computer Communications (INFOCOM)

CONFERENCE PAPER

Papalini M, Carzaniga A, Khazaei K, Wolf ALet al., 2014, Scalable routing for tag-based information-centric networking, Pages: 17-26

Routing in information-centric networking remains an open problem. The main issue is scalability. Traditional IP routing can be used with name prefixes, but it is believed that the number of prefixes will grow too large. A related problem is the use of per-packet in-network state (to cut loops and return data to consumers). We develop a routing scheme that solves these problems. The service model of our information-centric network supports information pull and push using tag sets as information descriptors. Within this service model, we propose a routing scheme that supports forwarding along multiple loop-free paths, aggregates addresses for scalability, does not require per-packet network state, and leads to near-optimal paths on average. We evaluate the scalability of our routing scheme, both in terms of memory and computational complexity, on the full Internet AS-level topology and on the internal networks of representative ASes using realistic distributions of content and users extrapolated from traces of popular applications. For example, a population of 500 million users requires a routing information base of 3.8GB with an almost at growth and, in this case, a routing update (one content descriptor) can be processed in 2ms on commodity hardware. We conclude that information-centric networking is feasible, even with (or perhaps thanks to) addresses consisting of expressive content descriptors.

CONFERENCE PAPER

Carzaniga A, Khazaei K, Papalini M, Wolf ALet al., 2013, Is Information-Centric Multi-Tree Routing Feasible?, ACM SIGCOMM COMPUTER COMMUNICATION REVIEW, Vol: 43, ISSN: 0146-4833

JOURNAL ARTICLE

Mai L, Rupprecht L, Costa P, Migliavacca M, Pietzuch P, Wolf ALet al., 2013, Supporting Application-specific In-network Processing in Data Centres, ACM SIGCOMM COMPUTER COMMUNICATION REVIEW, Vol: 43, Pages: 519-520, ISSN: 0146-4833

JOURNAL ARTICLE

Carzaniga A, Khazaei K, Papalini M, Wolf ALet al., 2013, Is information-centric multi-tree routing feasible?, Pages: 3-8

We have argued that an information-centric network should natively support publish/subscribe event notification in addition to on-demand content delivery. We have also argued that both primitives could use the same forwarding information base and, furthermore, that both primitives can easily support addresses that are more expressive than simple hierarchical names. In this paper we present a concrete routing scheme that realizes this: "push" as well as "pull" communication; anycast as well as multicast; and descriptor-based (as opposed to name-based) addressing. The scheme is founded on multiple tree covers that can be arranged and composed hierarchically following the structure of network domains. On each tree, the scheme combines addresses so as to reduce forwarding state. We demonstrate the feasibility and scalability of the scheme through simulations on Internet-scale workloads in realistic network settings. Copyright © 2013 ACM.

CONFERENCE PAPER

Mai L, Rupprecht L, Costa P, Migliavacca M, Pietzuch P, Wolf ALet al., 2013, Supporting application-specific in-network processing in data centres, SIGCOMM 2013 - Proceedings of the ACM SIGCOMM 2013 Conference on Applications, Technologies, Architectures, and Protocols for Computer Communication, Pages: 519-520

JOURNAL ARTICLE

Novotny P, Wolf AL, Ko BJ, 2013, Discovering Service Dependencies in Mobile Ad Hoc Networks, 13th IFIP/IEEE International Symposium on Integrated Network Management (IM), Publisher: IEEE, Pages: 527-533

CONFERENCE PAPER

Tati S, Novotny P, Ko BJ, Wolf A, Swami A, La Porta Tet al., 2013, Diagnosing Degradation of Services in Hybrid Wireless Tactical Networks, Conference on Ground/Air Multisensor Interoperability, Integration, and Networking for Persistent ISR IV, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, ISSN: 0277-786X

CONFERENCE PAPER

Novotny P, Wolf AL, Ko B-J, 2012, Fault Localization in MANET-Hosted Service-Based Systems

CONFERENCE PAPER

Costa P, Migliavacca M, Pietzuch P, Wolf ALet al., 2012, NaaS: Network-as-a-Service in the Cloud, 2nd USENIX Workshop on Hot Topics in Management of Internet, Cloud, and Enterprise Networks and Services

CONFERENCE PAPER

Carzaniga A, Papalini M, Wolf AL, 2011, Content-based publish/subscribe networking and information-centric networking, Pages: 56-61

On-line information comes in different forms and is accessed in different ways and for different purposes. For example, a recording of Beethoven's Ninth Symphony differs from a storm warning from the local weather service. Beethoven's Ninth is a large media file with perpetual validity that is typically accessed on demand by users. By contrast, a storm warning is a small ephemeral message typically pushed by the weather service to all users in a specific geographic area. We argue that both should and would be well supported by an information-centric network. More specifically we argue three points. First, modern applications, reflecting the nature of human communications, use and transmit large and long-lived files as well as small ephemeral messages. Second, accessing those two types of information involves significantly different operations within the network. Third, despite their differences, both types of information would benefit from an addressing scheme based on content rather than on more or less flat identifiers, which means that both should be integrated to some extent within a unified content-based routing infrastructure. © 2011 ACM.

CONFERENCE PAPER

Diaz J, Perez J, Garbajosa J, Wolf ALet al., 2011, Change Impact Analysis in Product-Line Architectures, 5th European Conference on Software Architecture, Pages: 114-129

CONFERENCE PAPER

Tarr PL, Wolf AL, 2011, Engineering of Software, Publisher: Springer-Verlag New York Incorporated, ISBN: 9783642198229

Introduction to “Engineering of Software: The Continuing Contributions of Leon J . Osterweil” Peri L. Tarr and Alexander L. Wolf Peri L. Tarr is at IBM Thomas J. Watson Research Center, PO Box 704, Yorktown Heights, NY 10598 USA, ...

BOOK

Diaz J, Perez J, Garbajosa J, Wolf ALet al., 2011, A Process for Documenting Variability Design Rationale of Flexible and Adaptive PLAs, Confederated International Workshops and Posters: EI2N plus NSF ICE, ICSP plus INBAST, ISDE, ORM, OTMA, SWWS plus MONET plus SeDeS, and VADER, Publisher: SPRINGER-VERLAG BERLIN, Pages: 612-+, ISSN: 0302-9743

CONFERENCE PAPER

Konstantinidis A, Carzaniga A, Wolf AL, 2011, A Content-Based Publish/Subscribe Matching Algorithm for 2D Spatial Objects, ACM/IFIP/USENIX 12th International Middleware Conference, Publisher: Springer, Pages: 208-227, ISSN: 0302-9743

CONFERENCE PAPER

Cadar C, Pietzuch P, Wolf AL, 2010, Multiplicity computing: A vision of software engineering for next-generation computing platform applications, Pages: 81-85

New technologies have recently emerged to challenge the very nature of computing: multicore processors, virtualized operating systems and networks, and data-center clouds. One can view these technologies as forming levels within a new, global computing platform. We aim to open a new area of research, called multiplicity computing, that takes a radically different approach to the engineering of applications for this platform. Unlike other efforts, which are largely focused on innovations within specific levels, multiplicity computing embraces the platform as a virtually unlimited space of essentially redundant resources. This space is formed as a whole from the cross product of resources available at each level in the platform, offering a "multiplicity" of end-to-end resources. We seek to discover fundamentally new ways of exploiting the combinatorial multiplicity of computational, communication, and storage resources to obtain scalable applications exhibiting improved quality, dependability, and security that are both predictable and measurable. Copyright 2010 ACM.

CONFERENCE PAPER

Chaudron MRV, Wolf AL, 2009, Foreword to the doctoral symposium

CONFERENCE PAPER

Carzaniga A, Denaro G, Pezze M, Estublier J, Wolf ALet al., 2009, Toward Deeply Adaptive Societies of Digital Systems, 31st International Conference on Software Engineering New Ideas and Emerging Results Track, Pages: 331-334

CONFERENCE PAPER

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