Reza Ziaei

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SynchNet: A Petri Net Based Coordination Language for Distributed Objects

Lecture Notes in Computer Science, 2003

We present SynchNet, a compositional meta-level language for coordination of distributed. Its des... more We present SynchNet, a compositional meta-level language for coordination of distributed. Its design is based on the principle of separation of concerns, namely separation of the coordination from computational aspects. SynchNet can be used in combination with any objectbased language capable of expressing sequential behavior of objects. SynchNet, which is inspired by Petri nets, has a simple syntax and semantics, but is expressive enough to code many of the commonly used coordination patterns. The level of abstraction that it provides allows tools and techniques developed for Petri nets to be readily applied to analysis and verification of the specified coordination patterns.

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A Theory of May Testing for Asynchronous Calculi with Locality and No Name Matching

Lecture Notes in Computer Science, 2002

We present a theory of may testing for asynchronous calculi with locality and no name matching. L... more We present a theory of may testing for asynchronous calculi with locality and no name matching. Locality is a non-interference property that is common in systems based on object-paradigm. Concurrent languages such as Join and Pict disallow name matching, which is akin to pointer comparison in imperative languages, to provide for an abstract semantics that would allow useful program transformations.

A Theory of May Testing for Actors

Formal Methods for Open Object-Based Distributed Systems V, 2002

SynchNet: A Petri Net Based Coordination Language for Distributed Objects

Lecture Notes in Computer Science, 2003

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An equational logic and a coordination language for distributed objects

Building reliable distributed object-based systems is challenging. The work presented in this dis... more Building reliable distributed object-based systems is challenging. The work presented in this dissertation investigates two approaches to address some of these challenges: logical and linguistic. The first part of the dissertation presents a equational theory of may testing equivalence for asynchronous calculi with locality and no name matching. Name matching, which is similar to pointer comparison in imperative languages, is considered a harmful feature that prevents useful program transformations. A trace-based characterization of may testing is provided for a version of asynchronous π-calculus with locality and no name matching (called Lπ). Trace based characterizations simplify reasoning about equivalence of pairs of processes. Using the characterization, a complete axiomatization for the finitary fragment of the calculi is presented. The first part of the dissertation extends the may testing results to the Actor model of distributed object-based computation. The Actor model has been an inspiring model of distributed object-based computation for two decades. This part of the dissertation gives an overview of the Actor model and presents Aπ, a formalization of the Actor model as a typed asynchronous π-calculus. The type system imposes a certain discipline on the use of names to capture actor properties such as uniqueness and persistence. The notion of may testing in Aπ and a trace based characterization of Aπare then investigated. This characterization is compared with that of asynchronous π-calculus, and the differences that arise due to actor properties are highlighted. Even though the Actor model provides a strong foundation for distributed object based computation, its limited coordination capabilities make specification of coordination logics very difficult. To make up for this limitation, the second part of this dissertation presents SynchNet, a compositional meta-level language for coordination of distributed objects that is based on Petri Nets. Its design is based on the principle of separation of concerns, namely separation of the coordination from computational aspects. SynchNet can be used in combination with any object-based language iii capable of expressing sequential behavior of objects. Working towards a Ph.D. has been the most ambitious and challenging project of my life. Going through all these years in the graduate school would not have been possible without the help of many people, to whom I wish to express my gratitude. First and foremost, I am grateful to my advisor, Professor Gul Agha, for his advice and kind support in all stages of the Ph.D program. I thank him because of the way he influenced my research philosophy. He taught me how to balance idealism versus pragmatism in research. I would also like to thank him for his support through the times of personal difficulties. My gratitude goes to the members of my defense committee, professors Mahesh Viswanathan, Jose Meseguer, Michael Loui, and Paul Schupp for their interest in my work and for their useful feedback. Particularly, I would like to thank professor Viswanathan for rekindling the joy of working on formal methods at a time that I was discouraged to pursue this discipline. Our collaboration lead to most of my results in Modal Logics. I would also like to thank professors Jose Meseguer and Michael Loui, not only for their constructive remarks on my dissertation, but also for their unparalleled disciplined and meticulous research attitude that has been an inspiration to me. I am also greatly thankful to Professor Mehdi Harandi whose support in the first year of graduate school helped me go through the difficult process of adjusting to a new and challenging environment. I would always remember his and his wife, Farideh, for their personal support throughout all these years. I would like to thank my colleagues and friends in the department of computer science who in one way or other kept me motivated all along and helped me realize that research is more effective as a group activity. I would like to thank Cesare Tinelli who was not only a great friend but also a great teacher. It was from him that I learned the fundamental meaning of logic and formal methods, which later became my main occupation. I will always remember all the pleasant nights vi we spent in Chicago restaurants with him and his wife Ana. I would also like to thank my colleague Prasanna Thati. Most of the first half of this dissertation is the result of collaboration with him. I am also grateful to all my peers in the department of computer science, especially Gloria Rendon, Duane Searsmith, and Joshua Kaplan. The Open System Laboratory was my research home for over six years. During this time I worked with many people who also made the times at OSL memorable. In particular, I would like to thanks

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Actors: a model for reasoning about open distributed systems

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Security and fault-tolerance in distributed systems: an actor-based approach

Proceedings Computer Security, Dependability, and Assurance: From Needs to Solutions (Cat. No.98EX358)

The inherent complexity of real-world distributed applications makes developing and maintaining s... more The inherent complexity of real-world distributed applications makes developing and maintaining software for these systems difficult and error-prone. We describe an actor-based meta-level model to address the complexity of distributed applications. Specifically, meta-level framework allow code implementing different design concerns to be factored into separate modules-thus enabling the separate development and modification of code for different non-functional requirements such as security and fault-tolerance. This paper reviews current research based on the model and outlines some research directions

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