Loo, Boon Thau
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Publication Towards Secure Cloud Data Management(2010-01-01) Zhou, Wenchao; Marczak, William R.; Sherr, Micah; Tao, Tao; Loo, Boon Thau; Zhang, Zhuoyao; Lee, InsupThis paper explores the security challenges posed by data-intensive applications deployed in cloud environments that span administrative and network domains. We propose a data-centric view of cloud security and discuss data management challenges in the areas of secure distributed data processing, end-to-end query result verification, and cross-user trust policy management. In addition, we describe our current and future efforts to investigate security challenges in cloud data management using the Declarative Secure Distributed Systems (DS2) platform, a declarative infrastructure for specifying, analyzing, and deploying secure information systems.Publication An Empirical Analysis of Scheduling Techniques for Real-Time Cloud-Based Data Processing(2011-12-01) Phan, Linh T.X.; Loo, Boon Thau; Zhang, Zhuoyao; Lee, Insup; Zheng, QiIn this paper, we explore the challenges and needs of current cloud infrastructures, to better support cloud-based data-intensive applications that are not only latency-sensitive but also require strong timing guarantees. These applications have strict deadlines (e.g., to perform time-dependent mission critical tasks or to complete real-time control decisions using a human-in-the-loop), and deadline misses are undesirable. To highlight the challenges in this space, we provide a case study of the online scheduling of MapReduce jobs executed by Hadoop. Our evaluations on Amazon EC2 show that the existing Hadoop scheduler is ill-equipped to handle jobs with deadlines. However, by adapting existing multiprocessor scheduling techniques for the cloud environment, we observe significant performance improvements in minimizing missed deadlines and tardiness. Based on our case study, we discuss a range of challenges in this domain posed by virtualization and scale, and propose our research agenda centered around the application of advanced real-time scheduling techniques in the cloud environment.Publication Analyzing P2P Overlays with Recursive Queries(2003-11-01) Loo, Boon Thau; Huebsch, Ryan; Hellerstein, Joseph M; Roscoe, Timothy; Stoica, IonWe explore the utility and execution of recursive queries as an interface for querying distributed network graph structures. To illustrate the power of recursive queries, we give several examples of computing structural properties of a P2P network such as reachability and resilience. To demonstrate the feasibility of our proposal, we sketch execution strategies for these queries using PIER, a P2P relational query processor over Distributed Hash Tables (DHTs). Finally, we discuss the relationship between in-network query processing and distance-vector like routing protocols.Publication Provenance-Aware Declarative Secure Networks(2007-12-05) Zhou, Wenchao; Cronin, Eric; Loo, Boon ThauIn recent years, network accountability and forensic analysis have become increasingly important, as a means of performing network diagnostics, identifying malicious nodes, enforcing trust management policies, and imposing diverse billing over the Internet. This has lead to a series of work to provide better network support for accountability, and efficient mechanisms to trace packets and information flows through the Internet. In this paper, we make the following contributions. First, we show that network accountability and forensic analysis can be posed generally as data provenance computations and queries over distributed streams. In particular, one can utilize provenance-aware declarative networks with appropriate security extensions to provide a flexible declarative framework for specifying, analyzing and auditing networks. Second, we propose a taxonomy of data provenance along multiple axes, and show that they map naturally to different use cases in networks. Third, we suggest techniques to efficiently compute and store network provenance, and provide an initial performance evaluation on the P2 declarative networking system with modifications to support provenance and authenticated communication.Publication Experiences in Teaching an Educational User-Level Operating Systems Implementation Project(2012-01-01) Aviv, Adam J; Mannino, Vin; Owlarn, Thanat; Shannin, Seth; Xu, Kevin; Loo, Boon ThauThe importance of a comprehensive implementation component for undergraduate Operating Systems (OS) courses cannot be understated. Students not only develop deep insight and understanding of OS fundamentals, but they also learn key software engineering skills that only a large development project, such as implementing an OS, can teach. There are clear benefits to traditional OS projects where students program or alter real (Linux) kernel source or extend educational OS implementations; however, in our experience, bootstrapping such a project is a huge undertaking that may not be accessible in many classrooms. In this paper, we describe a different approach to the OS implementation assignment: A user-level Operating System simulation based on UNIX preemptive signaling and threading constructs called ucontext. We believe that this variation of the implementation assignment provides many of the same educational benefits as traditional low-level projects without many of the expensive start-up costs. This project has been taught for a number of years at the University of Pennsylvania and was recently overhauled for the Fall 2011 semester. This paper describes the current version of the project and our experiences teaching it to a class of 54 students.Publication MOSAIC: Multiple Overlay Selection and Intelligent Composition(2007-10-24) Loo, Boon Thau; Ives, Zachary G; Mao, Yun; Smith, Jonathan MToday, the most effective mechanism for remedying shortcomings of the Internet, or augmenting it with new networking capabilities, is to develop and deploy a new overlay network. This leads to the problem of multiple networking infrastructures, each with independent advantages, and each developed in isolation. A greatly preferable solution is to have a single infrastructure under which new overlays can be developed, deployed, selected, and combined according to application and administrator needs. MOSAIC is an extensible infrastructure that enables not only the specification of new overlay networks, but also dynamic selection and composition of such overlays. MOSAIC provides declarative networking: it uses a unified declarative language (Mozlog) and runtime system to enable specification of new overlay networks, as well as their composition in both the control and data planes. Importantly, it permits dynamic compositions with both existing overlay networks and legacy applications. This paper demonstrates the dynamic selection and composition capabilities of MOSAIC with a variety of declarative overlays: an indirection overlay that supports mobility (i3), a resilient overlay (RON), and a transport-layer proxy. Using a remarkably concise specification, MOSAIC provides the benefits of runtime composition to simultaneously deliver application-aware mobility, NAT traversal and reliability with low performance overhead, demonstrated with deployment and measurement on both a local cluster and the PlanetLab testbed.Publication Declarative Automated Cloud Resource Orchestration(2011-10-01) Liu, CHangbin; Loo, Boon Thau; Mao, YunAs cloud computing becomes widely deployed, one of the challenges faced involves the ability to orchestrate a highly complex set of subsystems (compute, storage, network resources) that span large geographic areas serving diverse clients. To ease this process, we present COPE (Cloud Orchestration Policy Engine), a distributed platform that allows cloud providers to perform declarative automated cloud resource orchestration. In COPE, cloud providers specify system-wide constraints and goals using COPElog, a declarative policy language geared towards specifying distributed constraint optimizations. COPE takes policy specifications and cloud system states as input and then optimizes compute, storage and network resource allocations within the cloud such that provider operational objectives and customer SLAs can be better met. We describe our proposed integration with a cloud orchestration platform, and present initial evaluation results that demonstrate the viability of COPE using production traces from a large hosting company in the US. We further discuss an orchestration scenario that involves geographically distributed data centers, and conclude with an ongoing status of our work.Publication DMaC: Distributed Monitoring and Checking(2009-06-01) Zhou, Wenchao; Sokolsky, Oleg; Loo, Boon Thau; Lee, InsupWe consider monitoring and checking formally specified properties in a network. We are addressing the problem of deploying the checkers on different network nodes that provide correct and efficient checking. We present the DMaC system that builds upon two bodies of work: the Monitoring and Checking (MaC) framework, which provides means to monitor and check running systems against formally specified requirements, and declarative networking, a declarative domain-specific approach for specifying and implementing distributed network protocols. DMaC uses a declarative networking system for both specifying network protocols and performing checker execution. High-level properties are automatically translated from safety property specifications in the MaC framework into declarative networking queries and integrated into the rest of the network for monitoring the safety properties. We evaluate the flexibility and efficiency of DMaC using simple but realistic network protocols and their propertiesPublication Ontologies for Distributed Command and Control Messaging(2010-05-01) Nguyen, Duc N.; Kopena, Joseph B.; Loo, Boon Thau; Regli, William C.This paper presents the development of a set of ontologies for use in messaging systems within military and emergency first responder command and control applications. These ontologies are used to annotate and subscribe to messages within a content delivery and service discovery middleware connecting sensors, services, and agents on the network. Ontologies serve an important role in this middleware in providing for flexible addressing and querying that increases the decoupling between senders and receivers afforded by the middleware. This is particularly important in the target applications, which feature heterogenous components and software versions spanning development organizations and deployment time. Discussed here are application uses, development methodology, evaluation criteria, and other notes on these ontologies and their creation. The goal of this paper is to provide useful input to others engaged in similar development efforts.Publication Declarative Networking: Language, Execution and Optimization(2006-06-01) Loo, Boon Thau; Condie, Tyson; Garofalakis, Minos; Gay, David E; Hellerstein, Joseph M; Maniatis, Petros; Ramakrishnan, Raghu; Roscoe, Timothy; Stoica, IonThe networking and distributed systems communities have recently explored a variety of new network architectures, both for application-level overlay networks, and as prototypes for a next-generation Internet architecture. In this context, we have investigated declarative networking: the use of a distributed recursive query engine as a powerful vehicle for accelerating innovation in network architectures [23, 24, 33]. Declarative networking represents a significant new application area for database research on recursive query processing. In this paper, we address fundamental database issues in this domain. First, we motivate and formally define the Network Datalog (NDlog) language for declarative network specifiations. Second, we introduce and prove correct relaxed versions of the traditional semi-naïve query evaluation technique, to overcome fundamental problems of the traditional technique in an asynchronous distributed setting. Third, we consider the dynamics of network state, and formalize the “"eventual consistency"” of our programs even when bursts of updates can arrive in the midst of query execution. Fourth, we present a number of query optimization opportunities that arise in the declarative networking context, including applications of traditional techniques as well as new optimizations. Last, we present evaluation results of the above ideas implemented in our P2 declarative networking system, running on 100 machines over the Emulab network testbed.