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120
Declarative information extraction using Datalog with embedded extraction predicates
- in VLDB
, 1997
"... In this paper we argue that developing information extraction (IE) programs using Datalog with embedded procedural extraction predicates is a good way to proceed. First, compared to current ad-hoc composition using, e.g., Perl or C++, Datalog provides a cleaner and more powerful way to compose small ..."
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Cited by 77 (11 self)
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In this paper we argue that developing information extraction (IE) programs using Datalog with embedded procedural extraction predicates is a good way to proceed. First, compared to current ad-hoc composition using, e.g., Perl or C++, Datalog provides a cleaner and more powerful way to compose small extraction modules into larger programs. Thus, writing IE programs this way retains and enhances the important advantages of current approaches: programs are easy to understand, debug, and modify. Second, once we write IE programs in this framework, we can apply query optimization techniques to them. This gives programs that, when run over a variety of data sets, are more efficient than any monolithic program because they are optimized based on the statistics of the data on which they are invoked. We show how optimizing such programs raises challenges specific to text data that cannot be accommodated in the current relational optimization framework, then provide initial solutions. Extensive experiments over real-world data demonstrate that optimization is indeed vital for IE programs and that we can effectively optimize IE programs written in this proposed framework. 1.
Declarative Networking
, 2009
"... Declarative Networking is a programming methodology that enables developers to concisely specify network protocols and services, which are directly compiled to a dataflow framework that executes the specifications. This paper provides an introduction to basic issues in declarative networking, includ ..."
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Cited by 76 (31 self)
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Declarative Networking is a programming methodology that enables developers to concisely specify network protocols and services, which are directly compiled to a dataflow framework that executes the specifications. This paper provides an introduction to basic issues in declarative networking, including language design, optimization and dataflow execution. We present the intuition behind declarative programming of networks, including roots in Datalog, extensions for networked environments, and the semantics of long-running queries over network state. We focus on a sublanguage we call Network Datalog (NDlog), including execution strategies that provide crisp eventual consistency semantics with significant flexibility in execution. We also describe a more general language called Overlog, which makes some compromises between expressive richness and semantic guarantees. We provide an overview of declarative network protocols, with a focus on routing protocols and overlay networks. Finally, we highlight related work in declarative networking, and new declarative approaches to related problems.
The Declarative Imperative Experiences and Conjectures in Distributed Logic
"... The rise of multicore processors and cloud computing is putting enormous pressure on the software community to find solutions to the difficulty of parallel and distributed programming. At the same time, there is more—and more varied—interest in data-centric programming languages than at any time in ..."
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Cited by 50 (5 self)
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The rise of multicore processors and cloud computing is putting enormous pressure on the software community to find solutions to the difficulty of parallel and distributed programming. At the same time, there is more—and more varied—interest in data-centric programming languages than at any time in computing history, in part because these languages parallelize naturally. This juxtaposition raises the possibility that the theory of declarative database query languages can provide a foundation for the next generation of parallel and distributed programming languages. In this paper I reflect on my group’s experience over seven years using Datalog extensions to build networking protocols and distributed systems. Based on that experience, I present a number of theoretical conjectures that may both interest the database community, and clarify important practical issues in distributed computing. Most importantly, I make a case for database researchers to take a leadership role in addressing the impending programming crisis. This is an extended version of an invited lecture at the ACM PODS 2010 conference [32]. 1.
Naiad: A Timely Dataflow System
"... Naiad is a distributed system for executing data parallel, cyclic dataflow programs. It offers the high throughput of batch processors, the low latency of stream processors, and the ability to perform iterative and incremental computations. Although existing systems offer some of these features, app ..."
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Cited by 48 (1 self)
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Naiad is a distributed system for executing data parallel, cyclic dataflow programs. It offers the high throughput of batch processors, the low latency of stream processors, and the ability to perform iterative and incremental computations. Although existing systems offer some of these features, applications that require all three have relied on multiple platforms, at the expense of efficiency, maintainability, and simplicity. Naiad resolves the complexities of combining these features in one framework. A new computational model, timely dataflow, underlies Naiad and captures opportunities for parallelism across a wide class of algorithms. This model enriches dataflow computation with timestamps that represent logical points in the computation and provide the basis for an efficient, lightweight coordination mechanism. We show that many powerful high-level programming models can be built on Naiad’s low-level primitives, enabling such diverse tasks as streaming data analysis, iterative machine learning, and interactive graph mining. Naiad outperforms specialized systems in their target application domains, and its unique features enable the development of new high-performance applications. 1
Efficient Querying and Maintenance of Network Provenance at Internet-Scale
, 2010
"... Network accountability, forensic analysis, and failure diagnosis are becoming increasingly important for network management and security. Such capabilities often utilize network provenance – the ability to issue queries over network meta-data. For example, network provenance may be used to trace the ..."
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Cited by 48 (26 self)
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Network accountability, forensic analysis, and failure diagnosis are becoming increasingly important for network management and security. Such capabilities often utilize network provenance – the ability to issue queries over network meta-data. For example, network provenance may be used to trace the path a message traverses on the network as well as to determine how message data were derived and which parties were involved in its derivation. This paper presents the design and implementation of ExSPAN, a generic and extensible framework that achieves efficient network provenance in a distributed environment. We utilize the database notion of data provenance to “explain ” the existence of any network state, providing a versatile mechanism for network provenance. To achieve such flexibility at Internet-scale, ExSPAN uses declarative networking in which network protocols can be modeled as continuous queries over distributed streams and specified concisely in a declarative query language. We extend existing data models for provenance developed in database literature to enable distribution at Internet-scale, and investigate numerous optimization techniques to maintain and query distributed network provenance efficiently. The ExSPAN prototype is developed using Rapid-Net, a declarative networking platform based on the emerging ns-3 toolkit. Experiments over a simulated network and an actual deployment in a testbed environment demonstrate that our system supports a wide range of distributed provenance computations efficiently, resulting in significant reductions in bandwidth costs compared to traditional approaches.
DKAL: Distributed-Knowledge Authorization Language.
- In Proc. of CSF
, 2008
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“Networking is IPC”: A Guiding Principle to a Better Internet
, 2008
"... This position paper outlines a new network architecture, i.e., a style of construction that identifies the objects and how they relate. We do not specify particular protocol implementations or specific interfaces and policies. After all, it should be possible to change protocols in an architecture w ..."
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Cited by 38 (25 self)
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This position paper outlines a new network architecture, i.e., a style of construction that identifies the objects and how they relate. We do not specify particular protocol implementations or specific interfaces and policies. After all, it should be possible to change protocols in an architecture without changing the architecture. Rather we outline the repeating patterns and structures, and how the proposed model would cope with the challenges faced by today’s Internet (and that of the future). Our new architecture is based on the following principle: Application processes communicate via a distributed interprocess communication (IPC) facility. The application processes that make up this facility provide a protocol that implements an IPC mechanism, and a protocol for managing distributed IPC (routing, security and other management tasks). Existing implementation strategies, algorithms, and protocols can be cast and used within our proposed new structure.
Meld: A declarative approach to programming ensembles
- In Proceedings of the IEEE International Conference on Robots and Systems IROS ’07
, 2007
"... Abstract — This paper presents Meld, a programming language for modular robots, i.e., for independently executing robots where inter-robot communication is limited to immediate neighbors. Meld is a declarative language, based on P2, a logicprogramming language originally designed for programming ove ..."
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Cited by 37 (8 self)
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Abstract — This paper presents Meld, a programming language for modular robots, i.e., for independently executing robots where inter-robot communication is limited to immediate neighbors. Meld is a declarative language, based on P2, a logicprogramming language originally designed for programming overlay networks. By using logic programming, the code for an ensemble of robots can be written from a global perspective, as opposed to a large collection of independent robot views. This greatly simplifies the thought process needed for programming large ensembles. Initial experience shows that this also leads to a considerable reduction in code size and complexity. An initial implementation of Meld has been completed and has been used to demonstrate its effectiveness in the Claytronics simulator. Early results indicate that Meld programs are considerably more concise (more than 20x shorter) than programs written in C++, while running nearly as efficiently. I.
Declarative Network Verification
, 2009
"... In this paper, we present our initial design and implementation of a declarative network verifier (DNV). DNV utilizes theorem proving, a well established verification technique where logic-based axioms that automatically capture network semantics are generated, and a userdriven proof process is used ..."
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Cited by 35 (16 self)
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In this paper, we present our initial design and implementation of a declarative network verifier (DNV). DNV utilizes theorem proving, a well established verification technique where logic-based axioms that automatically capture network semantics are generated, and a userdriven proof process is used to establish network correctness properties. DNV takes as input declarative networking specifications written in the Network Datalog (NDlog) query language, and maps that automatically into logical axioms that can be directly used in existing theorem provers to validate protocol correctness. DNV is a significant improvement compared to existing use case of theorem proving which typically require several man-months to construct the system specifications. Moreover, NDlog, a high-level specification, whose semantics are precisely compiled into DNV without loss, can be directly executed as implementations, hence bridging specifications, verification, and implementation. To validate the use of DNV, we present case studies using DNV in conjunction with the PVS theorem prover to verify routing protocols, including eventual properties of protocols in dynamic settings.
