Shankar, A. Udaya
Overview
Works:  51 works in 98 publications in 1 language and 642 library holdings 

Roles:  Author 
Classifications:  QA76.M3, 005.1 
Publication Timeline
.
Most widely held works by
A. Udaya Shankar
Distributed programming : theory and practice by
A. Udaya Shankar(
Book
)
12 editions published between 2012 and 2013 in English and held by 87 WorldCat member libraries worldwide
Distributed programming: theory and practice presents a practical and rigorous method to develop distributed programs that correctly implement their specifications. The method also covers how to write specifications and how to use them. Numerous examples such as bounded buffers, distributed locks, messagepassing services, and distributed termination detection illustrate the method. Larger examples include data transfer protocols, distributed shared memory, and TCP network sockets. Distributed Programming: Theory and Practice bridges the gap between books that focus on specific concurrent programming languages and books that focus on distributed algorithms. Programs are written in a "reallife" programming notation, along the lines of Java and Python with explicit instantiation of threads and programs. Students and programmers will see these as programs and not "merely" algorithms in pseudocode. The programs implement interesting algorithms and solve problems that are large enough to serve as projects in programming classes and software engineering classes. Exercises and examples are included at the end of each chapter with online access to the solutions. Distributed Programming: Theory and Practice is designed as an advancedlevel text book for students in computer science and electrical engineering. Programmers, software engineers and researchers working in this field will also find this book usefulPublisher
12 editions published between 2012 and 2013 in English and held by 87 WorldCat member libraries worldwide
Distributed programming: theory and practice presents a practical and rigorous method to develop distributed programs that correctly implement their specifications. The method also covers how to write specifications and how to use them. Numerous examples such as bounded buffers, distributed locks, messagepassing services, and distributed termination detection illustrate the method. Larger examples include data transfer protocols, distributed shared memory, and TCP network sockets. Distributed Programming: Theory and Practice bridges the gap between books that focus on specific concurrent programming languages and books that focus on distributed algorithms. Programs are written in a "reallife" programming notation, along the lines of Java and Python with explicit instantiation of threads and programs. Students and programmers will see these as programs and not "merely" algorithms in pseudocode. The programs implement interesting algorithms and solve problems that are large enough to serve as projects in programming classes and software engineering classes. Exercises and examples are included at the end of each chapter with online access to the solutions. Distributed Programming: Theory and Practice is designed as an advancedlevel text book for students in computer science and electrical engineering. Programmers, software engineers and researchers working in this field will also find this book usefulPublisher
A stepwise refinement heuristic for protocol construction by
A. Udaya Shankar(
Book
)
6 editions published between 1987 and 1990 in English and held by 10 WorldCat member libraries worldwide
Abstract: "We present a stepwise refinement heuristic to construct distributed systems. The heuristic is based upon a conditional refinement relation between system specifications, and a 'Marking'. It is applied to construct four sliding window protocols that provide reliable data transfer over unreliable communication channels. The protocols use moduloN sequence numbers. The first protocol is for channels that can only lose messages in transit. By refining this protocol, we obtain three protocols for channels that can lose, reorder and duplicate messages in transit. The protocols herein are less restrictive and easier to implement than sliding window protocols previously studied in the protocol verification literature."
6 editions published between 1987 and 1990 in English and held by 10 WorldCat member libraries worldwide
Abstract: "We present a stepwise refinement heuristic to construct distributed systems. The heuristic is based upon a conditional refinement relation between system specifications, and a 'Marking'. It is applied to construct four sliding window protocols that provide reliable data transfer over unreliable communication channels. The protocols use moduloN sequence numbers. The first protocol is for channels that can only lose messages in transit. By refining this protocol, we obtain three protocols for channels that can lose, reorder and duplicate messages in transit. The protocols herein are less restrictive and easier to implement than sliding window protocols previously studied in the protocol verification literature."
A leastsquares approximation technique with an application to the transient M/M/1 queue by
JeanChrysostome Bolot(
Book
)
2 editions published in 1991 in English and held by 9 WorldCat member libraries worldwide
Abstract: "Many timedependent quantities in queueing systems have very complicated closedform analytic expressions but relatively simple Laplace transforms. We present an approximation technique that exploits this property. The technique is based on Parseval's theorem and integration in the complex plane using the residue theorem. It yields simple approximations that are optimal in a leastsquares sense. Furthermore, it yields analytic expressions for the leastsquares error between the approximations and the exact solutions. The technique is demonstrated on the M/M/1 queue. We obtain approximations to the transient expected queue size for arbitrary values of the traffic intensity, assuming that the queue is initially empty
2 editions published in 1991 in English and held by 9 WorldCat member libraries worldwide
Abstract: "Many timedependent quantities in queueing systems have very complicated closedform analytic expressions but relatively simple Laplace transforms. We present an approximation technique that exploits this property. The technique is based on Parseval's theorem and integration in the complex plane using the residue theorem. It yields simple approximations that are optimal in a leastsquares sense. Furthermore, it yields analytic expressions for the leastsquares error between the approximations and the exact solutions. The technique is demonstrated on the M/M/1 queue. We obtain approximations to the transient expected queue size for arbitrary values of the traffic intensity, assuming that the queue is initially empty
Stepwise assertional design of distancevector routing algorithms by Cengiz Alaettinoğlu(
Book
)
2 editions published between 1992 and 1993 in English and held by 8 WorldCat member libraries worldwide
Abstract: "There are many kinds of distancevector algorithms for adaptive routing in widearea computer networks, ranging from the classical Distributed BellmanFord to several recent algorithms that have better performance. However, these algorithms have very complicated behaviors and their analyses in the literature has been incomplete (and operational). In this paper, we present a stepwise assertional design of a recently proposed distancevector algorithm. Our design starts with the Distributed BellmanFord and goes through two intermediate algorithms. The properties established for each algorithm hold for the succeeding algorithms."
2 editions published between 1992 and 1993 in English and held by 8 WorldCat member libraries worldwide
Abstract: "There are many kinds of distancevector algorithms for adaptive routing in widearea computer networks, ranging from the classical Distributed BellmanFord to several recent algorithms that have better performance. However, these algorithms have very complicated behaviors and their analyses in the literature has been incomplete (and operational). In this paper, we present a stepwise assertional design of a recently proposed distancevector algorithm. Our design starts with the Distributed BellmanFord and goes through two intermediate algorithms. The properties established for each algorithm hold for the succeeding algorithms."
An assertional proof of correctness and serializability of a distributed mutual exclusion algorithm based on path reversal by D Ginat(
Book
)
3 editions published in 1988 in English and held by 8 WorldCat member libraries worldwide
3 editions published in 1988 in English and held by 8 WorldCat member libraries worldwide
An introduction to assertional reasoning for safety properties of concurrent systems by
A. Udaya Shankar(
Book
)
2 editions published between 1990 and 1991 in English and held by 8 WorldCat member libraries worldwide
Abstract: "In this report, a concurrent system is modeled by a state transition system and fairness requirements. We reason about such systems using a subset of lineartime temporal logic, specifically, weakest preconditions, invariant assertions and leadsto assertions. This theory is applied to numerous examples."
2 editions published between 1990 and 1991 in English and held by 8 WorldCat member libraries worldwide
Abstract: "In this report, a concurrent system is modeled by a state transition system and fairness requirements. We reason about such systems using a subset of lineartime temporal logic, specifically, weakest preconditions, invariant assertions and leadsto assertions. This theory is applied to numerous examples."
Hierarchical interdomain routing protocol with ondemand ToS and policy resolution by Cengiz Alaettinoğlu(
Book
)
2 editions published between 1993 and 1994 in English and held by 8 WorldCat member libraries worldwide
Our protocol handles topology changes, including node/link failures that partition superdomains."
2 editions published between 1993 and 1994 in English and held by 8 WorldCat member libraries worldwide
Our protocol handles topology changes, including node/link failures that partition superdomains."
Modular design principles for protocols with an application to the transport layer by
A. Udaya Shankar(
Book
)
2 editions published between 1990 and 1991 in English and held by 6 WorldCat member libraries worldwide
Each specification offers both connection management and connectionbased data transfer. We show how any connectionless data transfer protocol can be transformed to offer connectionbased data transfer service."
2 editions published between 1990 and 1991 in English and held by 6 WorldCat member libraries worldwide
Each specification offers both connection management and connectionbased data transfer. We show how any connectionless data transfer protocol can be transformed to offer connectionbased data transfer service."
Viewserver hierarchy : a scalable and adaptive interdomain routing protocol by Cengiz Alaettinoğlu(
Book
)
2 editions published in 1993 in English and held by 6 WorldCat member libraries worldwide
Domainlevel views are maintained by special nodes called viewservers. Each viewserver maintains a domainlevel view of a surrounding precinct. Viewservers are organized hierarchically. To obtain domainlevel source routes, the views of one or more viewservers are merged (upto [sic] a maximum of twice the levels in the hierarchy)."
2 editions published in 1993 in English and held by 6 WorldCat member libraries worldwide
Domainlevel views are maintained by special nodes called viewservers. Each viewserver maintains a domainlevel view of a surrounding precinct. Viewservers are organized hierarchically. To obtain domainlevel source routes, the views of one or more viewservers are merged (upto [sic] a maximum of twice the levels in the hierarchy)."
A relational notation for state transition systems by
Simon S Lam(
Book
)
3 editions published between 1988 and 1989 in English and held by 6 WorldCat member libraries worldwide
The relational notation has two basic constructs: state formulas that represent sets of states, and event formulas that represent sets of state transitions. A relational specification consists of a state transition system, given in the relational notation, and a set of fairness assumptions. Several refinement relations between specifications are defined. To illustrate our concepts and methods, three specifications of the alternatingbit protocol are given. We also apply the theory to explain auxiliary variables. Other applications of the theory to protocol verification, composition, and conversion are discussed. Our approach is compared with the approaches of other authors
3 editions published between 1988 and 1989 in English and held by 6 WorldCat member libraries worldwide
The relational notation has two basic constructs: state formulas that represent sets of states, and event formulas that represent sets of state transitions. A relational specification consists of a state transition system, given in the relational notation, and a set of fairness assumptions. Several refinement relations between specifications are defined. To illustrate our concepts and methods, three specifications of the alternatingbit protocol are given. We also apply the theory to explain auxiliary variables. Other applications of the theory to protocol verification, composition, and conversion are discussed. Our approach is compared with the approaches of other authors
Specifying modules to satisfy interfaces : a state transition system approach by
Simon S Lam(
Book
)
3 editions published between 1988 and 1991 in English and held by 6 WorldCat member libraries worldwide
We then provide specifications of two modules, one based upon twophase locking and the other multiversion timestamps; the twophase locking module uses an interface offered by a physical database. We prove that each module offers the serializable interface."
3 editions published between 1988 and 1991 in English and held by 6 WorldCat member libraries worldwide
We then provide specifications of two modules, one based upon twophase locking and the other multiversion timestamps; the twophase locking module uses an interface offered by a physical database. We prove that each module offers the serializable interface."
A simple nearoptimal solution to the drinking philosophers problem by D Ginat(
Book
)
2 editions published in 1989 in English and held by 5 WorldCat member libraries worldwide
Abstract: "We provide a solution to the drinking philosophers problem, defined by Chandy and Misra [1]. Our solution, unlike theirs, does not have a dining layer. By using bounded session numbers with occasional resets, we are able to reduce the message complexity per drinking session from the order of neighbors a philosopher has to the order of bottles he needs for drinking."
2 editions published in 1989 in English and held by 5 WorldCat member libraries worldwide
Abstract: "We provide a solution to the drinking philosophers problem, defined by Chandy and Misra [1]. Our solution, unlike theirs, does not have a dining layer. By using bounded session numbers with occasional resets, we are able to reduce the message complexity per drinking session from the order of neighbors a philosopher has to the order of bottles he needs for drinking."
Performance comparison of routing protocols using MaRS : distancevector versus linkstate(
Book
)
1 edition published in 1991 in English and held by 5 WorldCat member libraries worldwide
Abstract: "There are two approaches to adaptive routing protocols for widearea storeandforward networks: distancevector and linkstate. Distancevector algorithms use O(N x e) storage at each node, whereas linkstate algorithms use O(N²), where N is the number of nodes in the network and e is the average degree of a node. The ARPANET started with a distancevector algorithm (Distributed BellmanFord), but because of longlived loops, changed to a linkstate algorithm (SPF). We show, using a recently developed network simulator, MaRS, that a newly proposed distancevector algorithm (ExBF) performs as well as SPF. This suggests that distancevector algorithms are appropriate for very large widearea networks."
1 edition published in 1991 in English and held by 5 WorldCat member libraries worldwide
Abstract: "There are two approaches to adaptive routing protocols for widearea storeandforward networks: distancevector and linkstate. Distancevector algorithms use O(N x e) storage at each node, whereas linkstate algorithms use O(N²), where N is the number of nodes in the network and e is the average degree of a node. The ARPANET started with a distancevector algorithm (Distributed BellmanFord), but because of longlived loops, changed to a linkstate algorithm (SPF). We show, using a recently developed network simulator, MaRS, that a newly proposed distancevector algorithm (ExBF) performs as well as SPF. This suggests that distancevector algorithms are appropriate for very large widearea networks."
Performance comparison of routing protocols under dynamic and static file transfer connections(
Book
)
1 edition published in 1992 in English and held by 5 WorldCat member libraries worldwide
Abstract: "We compare the performance of two recently proposed distancevector algorithms (MerlinSegall and Extended BellmanFord) with a linkstate algorithm (SPF), under varying file transfer workload. (Unlike the traditional distancevector algorithms, these new distancevector algorithms do not suffer from longlived loops.) Our comparison is done using a recently developed network simulator, MaRS. We consider both dynamic and static file transfer connections, and both uniform and hotspot distributions of sourcesink pairs. Our conclusion is that Extended BellmanFord performs as well as SPF. This suggests that distancevector algorithms are appropriate for very large widearea networks, since their space requirements are less than that of linkstate algorithms."
1 edition published in 1992 in English and held by 5 WorldCat member libraries worldwide
Abstract: "We compare the performance of two recently proposed distancevector algorithms (MerlinSegall and Extended BellmanFord) with a linkstate algorithm (SPF), under varying file transfer workload. (Unlike the traditional distancevector algorithms, these new distancevector algorithms do not suffer from longlived loops.) Our comparison is done using a recently developed network simulator, MaRS. We consider both dynamic and static file transfer connections, and both uniform and hotspot distributions of sourcesink pairs. Our conclusion is that Extended BellmanFord performs as well as SPF. This suggests that distancevector algorithms are appropriate for very large widearea networks, since their space requirements are less than that of linkstate algorithms."
Typeofservice in adaptive nexthop routing by
Ibrahim Matta(
Book
)
1 edition published in 1992 in English and held by 5 WorldCat member libraries worldwide
We compare our approach with the traditional approach using a recently developed routing testbed, MaRS. The proposed approach offers lower endtoend delay to the delaysensitive traffic. A related property is that the routes for the delaysensitive traffic are more stable, i.e. less oscillations. An unexpected property is that the throughputsensitive traffic also has lower delays; this is because the link utilization metric makes the traffic move away to underutilized routes, thus isolating the two traffic classes and yielding a better overall network performance."
1 edition published in 1992 in English and held by 5 WorldCat member libraries worldwide
We compare our approach with the traditional approach using a recently developed routing testbed, MaRS. The proposed approach offers lower endtoend delay to the delaysensitive traffic. A related property is that the routes for the delaysensitive traffic are more stable, i.e. less oscillations. An unexpected property is that the throughputsensitive traffic also has lower delays; this is because the link utilization metric makes the traffic move away to underutilized routes, thus isolating the two traffic classes and yielding a better overall network performance."
Specifying an implementation to satisfy interface specifications : a state transition approach by
Simon S Lam(
Book
)
5 editions published between 1988 and 1989 in English and Undetermined and held by 5 WorldCat member libraries worldwide
We present a solution to the problem posed by Leslie Lamport to participants of the Specification Logics session in the 1987 Lake Arrowhead workshop. Formal specifications are given for a database interface offering serializable access to concurrent client programs, a twophase locking implementation of the client interface, and the physicaldatabase interface accessed by the implementation. We sketch a proof that the implementation satisfies the client interface specification, assuming that the physicaldatabase interface specification holds
5 editions published between 1988 and 1989 in English and Undetermined and held by 5 WorldCat member libraries worldwide
We present a solution to the problem posed by Leslie Lamport to participants of the Specification Logics session in the 1987 Lake Arrowhead workshop. Formal specifications are given for a database interface offering serializable access to concurrent client programs, a twophase locking implementation of the client interface, and the physicaldatabase interface accessed by the implementation. We sketch a proof that the implementation satisfies the client interface specification, assuming that the physicaldatabase interface specification holds
A simple assertional proof system for realtime systems by
A. Udaya Shankar(
Book
)
1 edition published in 1992 in English and held by 5 WorldCat member libraries worldwide
Abstract: "We present a simple proof system for a realtime system model similar to that of timed I/O automata. By introducing state variables indicating the last event occurrence time and event deadline time, we can express realtime properties in terms of traditional safety and progress assertions (e.g. invariant, unless, and leadsto) which are interpreted in the standard way. As a result, we can prove them using traditional proof rules (with weak fairness assumptions being replaced by finite upper bound timing assumptions). Unlike other approaches, we do not use a 'current time' variable. The proof system is illustrated on a real time mutual exclusion algorithm. We have also applied it to examples from the timed I/O automata literature."
1 edition published in 1992 in English and held by 5 WorldCat member libraries worldwide
Abstract: "We present a simple proof system for a realtime system model similar to that of timed I/O automata. By introducing state variables indicating the last event occurrence time and event deadline time, we can express realtime properties in terms of traditional safety and progress assertions (e.g. invariant, unless, and leadsto) which are interpreted in the standard way. As a result, we can prove them using traditional proof rules (with weak fairness assumptions being replaced by finite upper bound timing assumptions). Unlike other approaches, we do not use a 'current time' variable. The proof system is illustrated on a real time mutual exclusion algorithm. We have also applied it to examples from the timed I/O automata literature."
Construction of sliding window protocols by
A. Udaya Shankar(
Book
)
4 editions published in 1986 in English and held by 4 WorldCat member libraries worldwide
No abstract
4 editions published in 1986 in English and held by 4 WorldCat member libraries worldwide
No abstract
An iterative approach to comprehensive performance evaluation of integrated services networks by
Ibrahim Matta(
Book
)
1 edition published in 1994 in English and held by 4 WorldCat member libraries worldwide
These equations can be solved numerically, allowing the investigation of various control schemes for both transient and steady state performances. Preliminary results indicate that our approach is computationally much cheaper than discreteevent simulation, and yields sufficiently accurate performance measures. We use our model to compare the performance of different routing schemes on the NSFNET backbone topology with a weighted fairqueueing link scheduling discipline and admission control based on bandwidth reservation. We show that a routing scheme that routes connections on paths which are both underutilized and short (in number of hops) gives the highest network throughput."
1 edition published in 1994 in English and held by 4 WorldCat member libraries worldwide
These equations can be solved numerically, allowing the investigation of various control schemes for both transient and steady state performances. Preliminary results indicate that our approach is computationally much cheaper than discreteevent simulation, and yields sufficiently accurate performance measures. We use our model to compare the performance of different routing schemes on the NSFNET backbone topology with a weighted fairqueueing link scheduling discipline and admission control based on bandwidth reservation. We show that a routing scheme that routes connections on paths which are both underutilized and short (in number of hops) gives the highest network throughput."
Reasoning assertionally about realtime systems by
A. Udaya Shankar(
Book
)
1 edition published in 1993 in English and held by 4 WorldCat member libraries worldwide
Our method is illustrated on a nontrivial example consisting of three concurrent programs: a sensor that buffers inputs from the environment, an integrator that periodically integrates the buffered inputs into a database, and a queryhandler that responds to queries from the environment by accessing the database. We model the system for two different programtoprocessor allocations (dedicated processors and shared processors with priority scheduling). We prove that the system satisfies desired properties (e.g. bounded query response time and absence of buffer overflow)
1 edition published in 1993 in English and held by 4 WorldCat member libraries worldwide
Our method is illustrated on a nontrivial example consisting of three concurrent programs: a sensor that buffers inputs from the environment, an integrator that periodically integrates the buffered inputs into a database, and a queryhandler that responds to queries from the environment by accessing the database. We model the system for two different programtoprocessor allocations (dedicated processors and shared processors with priority scheduling). We prove that the system satisfies desired properties (e.g. bounded query response time and absence of buffer overflow)
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Related Identities
 Lam, Simon S. 1947 Author
 Alaettinoğlu, Cengiz Author
 Matta, Ibrahim Author
 Ginat, David Author
 Bolot, JeanChrysostome Author
 Agrawala, Ashok K.
 Murphy, Sandra L. Author
 Lam, S. S.
 Lee, David
 Plateau, Brigitte D.
Associated Subjects
Algorithms Approximation theory Approximation theoryData processing Automatic theorem proving Computer interfaces Computer network protocols Computer networks Computer programming Computer programsCorrectness Computer programsVerification Computer science Computer softwareVerification Conflict management Database management Electronic data processingDistributed processing Heuristic programming Integrated services digital networks Least squares Least squaresData processing Logic design Mathematical notation Packet switching (Data transmission) Parallel processing (Electronic computers) Parallel programming (Computer science) Predicate (Logic) Problem solving Queuing theory Realtime data processing Routingmachines Software engineering TexasAustin User interfaces (Computer systems)
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