2596226
Towards an Internet-Scale XML Dissemination Service
Publish/subscribe systems have demonstrated the ability to scale to large numbers of users and high data rates when providing content-based data dissemination services on the Internet. However, their services are limited by the data semantics and query expressiveness that they support. On the other hand, the recent work on selective dissemination of XML data has made significant progress in moving from XML filtering to the richer functionality of transformation for result customization, but in general has ignored the challenges of deploying such XML-based services on an Internet-scale. In this paper, we address these challenges in the context of incorporating the rich functionality of XML data dissemination in a highly scalable system. We present the architectural design of ONYX, a system based on an overlay network. We identify the salient technical challenges in supporting XML filtering and transformation in this environment and propose techniques for solving them.
2033914
Data Staging for On-Demand Broadcast
:A>@<b_DCGAdPBEG>R<:c\A8:Q@L]J.A8<0H(L[MOz:CTL0PBc:zbP[<bc4EGADCG ? >@_DA8EHGbP[HP[CTA>@<::ADCTAD<.HTQRJz:CTL0PBcb_DPBEwHw_DPBbP[zbQRA bP0EqPBc\A>Uc\ADPBCGAdP$c:P]HFP z:CGL.PBc:_8PBEwHP[<P]HGHGCFPB_ HG>@?BA4c:P]HFP c\A8QR>@?BA8CGJ P[QRHGA8CG<kP]HG>@?BA2MSLBCQ@PBCG0A&_Q@>RA8<.H  LB:a:QUP]HT>RL0<bE8`v:ADCTAbP0Evz ADAD<Ew>@B<:>Rk_8P[<.HvyL0CGZ HGL]P[CFc:EOc\A8?BA8QRL0:>R<b$LB<\QR>@<:Az:CTL0P0c:_DP0EKHET_F:Adc\a:QR >@<:P[Q@BLBCT>RHG:E MSLBCEGJ\EKHTADE :ADCTA!P[Q@Q c:P]HFP >RHGADEOPBCGAyCGAdPBc\>@QRJPY?]PB>RQUP[z:Q@A>@<¡HG:AEGADCT?BADCd¢ E6P[>@< ADLBCTJB` :A8EGA£EwHGabc:>RAdE(>@B<bLBCTA HG:Ac:P]HFP2P[<: P[0ADAD<.H>UETEwa:AdEOHTbP]HP[CT>@EGA:A8<HG:A c:P[HTP HTL£z A z:CTL0P0c:_DP0EKH£akEKH&z A L0z\HTPB>R<bA8c MSCGL0¤EGA8_DLB<bcbP[CTJ EwHGLBCFP[0A LBC,CTADL[HTA Q@L\_DP]HT>RL0<bE8`¥<¦HT:>@E4bPBkA8C8V  A§:CTLB L0EGA HG:CTADA_LB:Q@ADA8<0HFP[CTJ ̈EGLBQ@a\HG>@LB<kE HGL EGab_F ̈©Ba[«a ¬­«aD®B ̄±°.®_L0<b_A8CG<kED2§L0: LBCGHGa:<:>UEw HG>U_ ET_F:A8c:a:QR>@<:kVEGADCT?BA8C2_DP0_F:>R<bbVP[<bc bCGADMSAHT_F: >@<:b`&bA8EGAHGA8_Fb<:>@3.a:AdE$A ́\:Q@LB>RH:>@<.HTE$:CTL]? >@c:A8c z J,HG:AET_F:A8c\abQR>@<:,P[Q@BLBCT>RHG:,`$μ¶c:AHTPB>RQ@A8c kA8Cw MSLBCTP[<b_DA AD?]P[Q@abP]HT>RL0< akEw>@<:P[<·¥K ̧o1 a:QRHG>U_DPBEwHw zbP0EwAdc HGAdEKHTzkAdc EG:L]vE$HTbP]HHG:AdEwA4c:P]HFP EwHTPBB>@<: HGAd_F:<:>U3.a:A8Ev_8P[< c\CFP[P]HT>@_8P[Q@QRJA8<:bPB<b_A HT:A$kA8Cw MSLBCTP[<b_DA L[M£P Q@PBCG0AEG_8P[Q@A,LB<\c\ADPB<bcz:CTL0P0c  _DP0EKHvEGJ\EKHTAD,`
7889988
Crash recovery in client-server EXODUS
In this paper, we address the correctness and performance issues that arise when implementing logging and crash recovery in a page-server environment. The issues result from two characteristics of page-server systems: 1) the fact that data is modified and cached in client database buffers that are not accessible by the server, and 2) the performance and cost trade-offs that are inherent in a client-server environment. We describe a recovery system that we have implemented for the client-server version of the EXODUS storage manager. The implementation supports efficient buffer management policies, allows flexibility in the interaction between clients and the server, and reduces the server load by generating log records at clients. We also present a preliminary performance analysis of the implementation.
2567437
Dynamic Query Operator Scheduling for Wide-Area Remote Access
Distributed databases operating over wide-area networks such as the Internet, must deal with the unpredictable nature of the performance of communication. The response times of accessing remote sources can vary widely due to network congestion, link failure, and other problems. In such an unpredictable environment, the traditional iterator-based query execution model performs poorly. We have developed a class of methods, called query scrambling, for dealing explicitly with the problem of unpredictable response times. Query scrambling dynamically modifies query execution plans on-the-fly in reaction to unexpected delays in data access. In this paper we focus on the dynamic scheduling of query operators in the context of query scrambling. We explore various choices for dynamic scheduling and examine, through a detailed simulation, the effects of these choices. Our experimental environment considers pipelined and non-pipelined join processing in a client with multiple remote data sources and delayed or possibly bursty arrivals of data. Our performance results show that scrambling rescheduling is effective in hiding the impact of delays on query response time for a number of different delay scenarios.
2815522
Efficient Filtering of XML Documents for Selective Dissemination of Information
Information Dissemination applications are gaining increasing popularity due to dramatic improvements in communications bandwidth and ubiquity. The sheer volume of data available necessitates the use of selective approaches to dissemination in order to avoid overwhelming users with unnecessaryinformation. Existing mechanisms for selective dissemination typically rely on simple keyword matching or “bag of words” information retrieval techniques. The advent of XML as a standard for information exchangeand the development of query languages for XML data enables the development of more sophisticated filtering mechanisms that take structure information into account. We have developed several index organizations and search algorithms for performing efficient filtering of XML documents for large-scale information dissemination systems. In this paper we describe these techniques and examine their performance across a range of document, workload, and scale scenarios.
1006062
The design of an acquisitional query processor for sensor networks
We discuss the design of an acquisitional query processor for data collection in sensor networks. Acquisitional issues are those that pertain to where, when, and how often data is physically acquired (sampled) and delivered to query processing operators. By focusing on the locations and costs of acquiring data, we are able to significantly reduce power consumption over traditional passive systems that assume the a priori existence of data. We discuss simple extensions to SQL for controlling data acquisition, and show how acquisitional issues influence query optimization, dissemination, and execution. We evaluate these issues in the context of TinyDB, a distributed query processor for smart sensor devices, and show how acquisitional techniques can provide significant reductions in power consumption on our sensor devices.
3112017
Distribution chain security
Digital content distribution systems will enable business models in the near future that cannot be predicted today. In this paper, we identify a new security problem that can be crucial to this enablement. The problem arises from the con icting privacy and integrity goals of middlemen in digital distribution chains. Our solution is a novel system design that incorporates obfuscated digital contracts, semi-trusted contract certi ers, and zero-knowledge proofs of arithmetic relations. Our implementation and timing experiments demonstrate that our solution is practical and eÆcient.
61655346
Statistics on Logic Simulation
The high costs associated with logic simulation of large VLSI based systems have led to the need for new computer architectures tailored to the simulation task. Such architectures have the potential for significant speedups over standard software based logic simulators. Several commercial simulation engines have been produced to satisfy needs in this area. To properly explore the space of alternative simulation architectures, data is required on the simulation process itself. This paper presents a framework for such data gathering activity by first examining possible sources of speedup in the logic simulation task, examining the sort of data needed in the design of simulation engines, and then presenting such data. The data contained in the paper includes information on subtask times found in standard discrete event simulation algorithms, event intensities, queue length distributions and simultaneous event distributions.
18311613
Fair scheduling in an optical interconnection network
Existing fair scheduling schemes have focused primarily on scheduling multiple flows to a single output. The limited work that has focused on scheduling multiple flows to multiple outputs has assumed a non-blocking, slotted-time, cell-based network with a centralized controller. This paper presents a fair scheduler suitable for use in bufferless circuit-switched blocking networks operating with distributed, asynchronous controllers and variable length messages. We begin by describing the potential for starvation in the Gemini interconnect network, an optical, circuit-switched network. A proposed distributed fair scheduler is presented and shown to solve this problem. The tradeoffs and limitations of performing many-to-many fair scheduling in general, and that of our fair scheduler in particular, are discussed.
5720179
Enhancing privacy and trust in electronic communities
A major impediment to using recommendation systems and collective knowledge for electronic commerce is the reluctance of individuals to reveal preferences in order to find groups of people that share them. An equally important barrier to fluid electronic commerce is the lack of agreed upon trusted third parties. We propose new non-third party mechanisms to overcome these barriers. Our solutions facilitate finding shared preferences, discovering communities with shared values, removing disincentives posed by liabilities, and negotiating on behalf of a group. We adapt known techniques from the cryptographic literature to enable these new capabilities.
14211318
An architecture for fast processing of large unstructured data sets
This paper presents a general system architecture tailored to perform searching, filtering, compression, encryption, and other operations on unstructured data streaming from a disk system. The system achieves high performance on such applications by providing for parallelism, hardware-application specialization and reconfiguration, and hardware placement near the disk systems. A limited prototype of a single compute node has been implemented and is described. The prototype is tailored to applications involving complex searching and its performance is compared to a pure software implementation having the same search capabilities. Performance is considered in terms of data set size, query string hit rate and query complexity. Performance results as a function of these parameters are presented and the results indicate that, for data set sizes above 1.4 MB, the prototype compute node is between one and two orders of magnitude faster than a pure software implementation. At high data set sizes, on an individual node, speedups of about 200 and a sustained throughput of 300 MB/sec have been achieved.