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41
Web Dynamic
- Software Focus
, 2001
"... The global usage and continuing exponential growth of the World-Wide-Web poses a host of challenges to the research community. In particular, thereis an urgent need to understand and manage the dynamics of the Web, in order to develop new techniques which will make the Web tractable. We provide an o ..."
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Cited by 16 (2 self)
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The global usage and continuing exponential growth of the World-Wide-Web poses a host of challenges to the research community. In particular, thereis an urgent need to understand and manage the dynamics of the Web, in order to develop new techniques which will make the Web tractable. We provide an overview of recent statistics relating to the size of the Web graph and its growth. We then briefly review some of the key areas relating to Webdynamics with reference to the recent literature. Finally, we summarise the talks given in a recent workshop devoted to Webdynamics which was held in the beginning of January 2001 at the University of London. Keywords. Web dynamics, Web graph, information retrieval, collaborative filtering, Web navigation,Website design, data-intensive Web applications, workflow management, e-commerce,mobile computation.
Automatic Verification of Database-Driven Systems: A New Frontier
"... We describe a novel approach to verification of software systems centered around an underlying database. Instead of applying general-purpose techniques with only partial guarantees of success, it identifies restricted but reasonably expressive classes of applications and properties for which sound a ..."
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We describe a novel approach to verification of software systems centered around an underlying database. Instead of applying general-purpose techniques with only partial guarantees of success, it identifies restricted but reasonably expressive classes of applications and properties for which sound and complete verification can be performed in a fully automatic way. This leverages the emergence of high-level specification tools for database-centered applications that not only allow fast prototyping and improved programmer productivity but, as a side effect, provide convenient targets for automatic verification. We present theoretical and practical results on verification of database-driven systems. The results are quite encouraging and suggest that, unlike arbitrary software systems, significant classes of databasedriven systems may be amenable to automatic verification. This relies on a novel marriage of database and model checking techniques, of relevance to both the database and the computer aided verification communities. 1.
Inferring mixtures of markov chains
- 2004 Black, Paul E. “Markov Chain.” National Institute of Standards and Technology
, 2002
"... Abstract. We define the problem of inferring a “mixture of Markov chains ” based on observing a stream of interleaved outputs from these chains. We show a sharp characterization of the inference process. The problems we consider also has applications such as gene finding, intrusion detection, etc., ..."
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Abstract. We define the problem of inferring a “mixture of Markov chains ” based on observing a stream of interleaved outputs from these chains. We show a sharp characterization of the inference process. The problems we consider also has applications such as gene finding, intrusion detection, etc., and more generally in analyzing interleaved sequences. 1
Comparing Workflow Specification Languages: A Matter of Views
, 2011
"... We address the problem of comparing the expressiveness of workflow specification formalisms using a notion of view of a workflow. Views allow to compare widely different workflow systems by mapping them to a common representation capturing the observables relevant to the comparison. Using this frame ..."
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Cited by 9 (4 self)
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We address the problem of comparing the expressiveness of workflow specification formalisms using a notion of view of a workflow. Views allow to compare widely different workflow systems by mapping them to a common representation capturing the observables relevant to the comparison. Using this framework, we compare the expressiveness of several workflow specification mechanisms, including automata, temporal constraints, and pre-and-post conditions, with XML and relational databases as underlying datamodels. One surprising result shows the considerable power of static constraints to simulate apparently much richer workflow control mechanisms.
A Quest for Beauty and Wealth (or, Business Processes for Database Researchers)
, 2011
"... While classic data management focuses on the data itself, research on Business Processes considers also the context in which this data is generated and manipulated, namely the processes, the users, and the goals that this data serves. This allows the analysts a better perspective of the organization ..."
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Cited by 7 (1 self)
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While classic data management focuses on the data itself, research on Business Processes considers also the context in which this data is generated and manipulated, namely the processes, the users, and the goals that this data serves. This allows the analysts a better perspective of the organizational needs centered around the data. As such, this research is of fundamental importance. Much of the success of database systems in the last decade is due to the beauty and elegance of the relational model and its declarative query languages, combined with a rich spectrum of underlying evaluation and optimization techniques, and efficient implementations. This, in turn, has lead to an economic wealth for both the users and vendors of database systems. Similar beauty and wealth are sought for in the context of Business Processes. Much like the case for traditional database research, elegant modeling and rich underlying technology are likely to bring economic wealth for the Business Process owners and their users; both can benefit from easy formulation and analysis of the processes. While there have been many important advances in this research in recent years, there is still much to be desired: specifically, there have been many works that focus on the processes behavior (flow), and many that focus on its data, but only very few works have dealt with both. We will discuss here the important advantages of a holistic flow-and-data framework for Business Processes, the progress towards such a framework, and highlight the current gaps and research directions.
Complexity and Composition of Synthesized Web Services
, 2008
"... The paper investigates fundamental decision problems and composition synthesis for Web services commonly found in practice. We propose a notion of synthesized Web services (SWS’s) to specify the behaviors of the services. Upon receiving a sequence of input messages, an SWS issues multiple queries to ..."
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The paper investigates fundamental decision problems and composition synthesis for Web services commonly found in practice. We propose a notion of synthesized Web services (SWS’s) to specify the behaviors of the services. Upon receiving a sequence of input messages, an SWS issues multiple queries to a database and generates actions, in parallel; it produces external messages and database updates by synthesizing the actions parallelly generated. In contrast to previous models for Web services, SWS’s advocate parallel processing and (deterministic) synthesis of actions. We classify SWS’s based on what queries an SWS can issue, how the synthesis of actions is expressed, and whether unbounded input sequences are allowed in a single interaction session. We show that the behaviors of Web services supported by various prior models, data-driven or not, can be specified by different SWS classes. For each of these classes we study the non-emptiness, validation and equivalence problems, and establish matching upper and lower bounds on these problems. We also provide complexity bounds on composition synthesis for these SWS classes, identifying decidable cases.
Model Checking for Database Theoreticians
- IN ICDT’05
, 2005
"... Algorithmic verification is one of the most successful applications of automated reasoning in computer science. In algorithmic verification one uses algorithmic techniques to establish the correctness of the system under verification with respect to a given property. Model checking is an algorithmi ..."
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Cited by 5 (0 self)
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Algorithmic verification is one of the most successful applications of automated reasoning in computer science. In algorithmic verification one uses algorithmic techniques to establish the correctness of the system under verification with respect to a given property. Model checking is an algorithmic-verification technique that is based on a small number of key ideas, tying together graph theory, automata theory, and logic. In this self-contained talk I will describe how this "holy trinity" gave rise to algorithmic-verification tools, and discuss its applicability to database verification.
LTL formalization of BPML semantics and visual notation for linear temporal logic
"... As the Web becomes a platform for implementing complex B2C and B2B applications, the need arises of extending Web conceptual modeling from data-centric applications to data- and process-centric applications. New primitives must be put in place to implement workflows describing business processes. In ..."
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Cited by 4 (1 self)
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As the Web becomes a platform for implementing complex B2C and B2B applications, the need arises of extending Web conceptual modeling from data-centric applications to data- and process-centric applications. New primitives must be put in place to implement workflows describing business processes. In this context, new problems about process safety and verification arise. We study Web sites interacting with users or applications. We provide a formal data-driven model of the application, which can access an underlying database, as well as state information updated as the interaction progresses, and a set of user input. Against this Web application definition, we aim at verifying properties concerning the sequences of events, inputs, states, and actions, resulting from the interaction. In particular, we focus on workflow based properties, describing the execution flow of the tasks within the application. Such properties are expressed in linear or branching-time temporal logics. Since temporal logics properties are difficult to describe by a user, this work presents a visual approach that exploits and extends workflow notations (in particular, BPMN) for describing the rules to be verified. Some results from the same research group involved in this work establish under what conditions automatic verification of
Querying schemas with access restrictions
- PVLDB
"... We study verification of systems whose transitions consist of accesses to a Web-based data-source. An access is a lookup on a relation within a relational database, fixing values for a set of positions in the relation. For example, a transition can represent access to a Web form, where the user is r ..."
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We study verification of systems whose transitions consist of accesses to a Web-based data-source. An access is a lookup on a relation within a relational database, fixing values for a set of positions in the relation. For example, a transition can represent access to a Web form, where the user is re-stricted to filling in values for a particular set of fields. We look at verifying properties of a schema describing the possi-ble accesses of such a system. We present a language where one can describe the properties of an access path, and also specify additional restrictions on accesses that are enforced by the schema. Our main property language, AccLTL, is based on a first-order extension of linear-time temporal logic, interpreting access paths as sequences of relational struc-tures. We also present a lower-level automaton model, A-automata, which AccLTL specifications can compile into. We show that AccLTL and A-automata can express static analysis problems related to “querying with limited access patterns ” that have been studied in the database literature in the past, such as whether an access is relevant to an-swering a query, and whether two queries are equivalent in the accessible data they can return. We prove decidability and complexity results for several restrictions and variants of AccLTL, and explain which properties of paths can be expressed in each restriction. 1.
