B. Randell, A. Romanovsky, R. Stroud, J. Xu and A.F. Zorzo, "Coordinated Atomic Actions: from Concept to Implementation," Technical Report, Department of Computer Science, University of Newcastle upon Tyne, no.595, 1997.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....the commit logic so that the wishes of all the participating clients must be 58 taken into accound We assume that all clients must agree on committing a transaction but that any client can force the abort of a transaction. This is similar in concept to the semantics of Coordinated Atomic Actions [74, 58] where participants must either agree on a normal or exceptional outcome, or abort the entire action. As our model of multi party transactions does not currently consider exceptions then the agreement must be on whether to commit. If there is no agreement to commit then the transaction is aborted. ....

B. Randell, A. Romanovsky, R. J. Stroud, J. Xu, and A. F. Zorzo. Coordinated atomic actions: from concept to implementation. Technical Report TR 595, Department of Computing, University of Newcastle upon Tyne, 1997.

....Distributed systems, CA actions, concurrency control, communicating sequential processes, fault tolerance, nondeterminism, partial and total correctness, verification, divergence, formal semantics. 1 Introduction 1. 1 Coordinated Atomic actions The Coordinated Atomic (CA) action concept [11, 15, 16] is an approach to structuring complex concurrent activities in a distributed environment, aimed at supporting fault tolerance in objectoriented systems. In its current presentation, the CA action model provides a conceptual framework in which fault tolerance is achieved by integrating the ....

Randell, B., Romanovsky, A., Stroud, R., Xu, J., Zorzo, A.F.: Coordinated Atomic Actions: From Concept to Implementation. Submitted to Special Issue of IEEE Transactions on Computers, (1997).

.... Distributed checkpointing algorithms are being developed since ChandyLamport [3] Strom Yemini [21] to the recent work at Illinois and Bell Laboratories [27] and at Texas A M [25] We use concepts of coordinated atomic actions and conversation model in this paper from the work done at Newcastle [18] and in [10] Research at LAAS and Newcastle [7, 8] originally used reflection for object level fault tolerance. Checkpointing libraries have been implemented for single threaded programs and for distributed systems. libckpt[17] the condor project at Wisconsin [23] probabilistic checkpointing ....

....assertions) is used. 5.3 Linguistic and Platform Relates Issues The concepts discussed in earlier sections are generic enough for use with any OO programming language. Earlier work on fault tolerance for conversation models and object oriented programs has used CSP [10] C [8] Ada and Java[18]. We find that the richness of features of C help in developing satisfactory solutions to many of the issues in the development that could be problems in other languages. However, it is this feature richness of C , that makes it difficult to cover all language features satisfactorily. For a ....

B. Randell, A. Romanovsky, R.J. Stroud, J. Xu, and A.F. Zorzo. Co-ordinated atomic actions: from concept to implementation. Technical Report TR 595, Computing Dept. , University of Newcastle upon Tyne, 1997.

....the pid server in parallel to the most external block (as for a global variable declaration) with the scoping on actions transmit , kill , allocpid , freepid and PS t . 6 Conclusion Concurrent exceptions has been addressed in literature, for instance in the context of Coordinated Atomic Actions [14] or Place Charts Nets [8] In this paper, we introduced static exceptions in a parallel programming language, B(PN) 2 , which is provided with a concurrent semantics based on Petri nets and for which implemented tools can be used [7] It turned out that combining these exceptions with ....

B. Randell, A. Romanovsky, R. J. Stroud, J. Xu and A. F. Zorzo. Coordinated Atomic Actions: from concept to implementation. Submitted to IEEE TC Special issue.

....a modi ed two phase commit protocol (2PC) 27] We allow multiple clients initiate the protocol. We assume that all clients must agree on committing a transaction but that any client can force the abort of a transaction. This is similar in concept to the semantics of Coordinated Atomic Actions [52, 36] where participants must either agree on a normal or exceptional outcome, or abort the entire action. As our model of multi party transactions does not currently consider exceptions then the agreement must be on whether to commit. If there is no agreement to commit then the transaction is aborted. ....

B. Randell, A. Romanovsky, R. J. Stroud, J. Xu, and A. F. Zorzo. Coordinated atomic actions: from concept to implementation. Technical Report TR 595, Department of Computing, University of Newcastle upon Tyne, 1997.

....systems such as process control or real time control applications, and concentrate on the issues of factoring and organizing the interactions between process without addressing the problem of consistency of shared objects accessed by these process. The concept of coordinated atomic action [12, 20] (or CA actions) is the rst attempt to integrate transactions and conversations into a single conceptual framework for coping with di erent kinds of concurrency and achieving fault tolerance. The CA action concept thus encompasses strategies for dealing with hardware and software faults to ....

B. Randell, A. Romanovsky, R.J. Stroud, J. Xu, and A.F. Zorzo. Coordinated Atomic Actions: from Concept to Implementation. Technical Report 595, Department of Computing Science, University of Newcastle upon Tyne, UK, 1997.

.... ACID) is the main concern. Processes want to access resources (objects, files, DBs, servers) as if they were at their exclusive disposal. Although transactional support allows concurrent access, this is transparent for processes. 2. Coordinated Atomic Actions The coordinated atomic (CA) action [7, 8] concept was introduced as a unified approach to structuring complex concurrent activities and supporting error recovery between multiple interacting objects in a object oriented (OO) system. This paradigm provides a conceptual framework for dealing with both kinds of concurrency (cooperative and ....

Randell, B., Romanovsky, A., Stroud, R., Xu, J., Zorzo, A.F. Coordinated atomic actions: from concept to implementation. DeVa TR-36, 1996 http://www.newcastle.research.ec.org/deva/trs/index.html

....Coordinated Atomic Actions to Design Dependable Distributed Object Systems A.Zorzo 1 , A.Romanovsky, J.Xu, B.Randell, R.Stroud, and I. Welch Department of Computing Science, University of Newcastle upon Tyne, UK 1 Introduction The Coordinated Atomic (CA) action concept [1] [2] is a unified approach to structuring complex concurrent activities and supporting error recovery between multiple interacting objects in an object oriented system. This paradigm provides a conceptual framework for supporting both cooperating and competing concurrency and achieving fault ....

....by objects composed of a set of role objects, a set of local objects, and a set of external objects. The CA action mechanism is responsible for managing synchronous entry and exit to actions, global exception handling, recovery, consistency and atomicity of external and local objects, and so on[1]. Figure 4 shows how the components of a CA action are distributed in our approach. host 6 object shared local from other CA Actions private local object corresponding role responsible the roles under control for its recovery host 1 external object atomic host 5 CA action connects ....

B. Randell, A. Romanovsky, R. J. Stroud, J. Xu, and A. F. Zorzo. "Coordinated Atomic Actions: from Concept to Implementation". Submitted to Special Issue of IEEE Transactions on Computers, 1997.

....use of the many advantages of object oriented programming while designing new object oriented atomic action schemes (including their supports) and applying them. 2. 5 Structuring Systems with Cooperative and Competitive Concurrency Developers of the Coordinated Atomic action (CA action) concept [25, 33] realised that many realistic systems to be modelled controlled by software have elements of both cooperation and competition and that it is important to allow them to be combined within one system. CA actions provide a framework for dealing with different kinds of concurrency and achieving fault ....

....exception, e1, is raised concurrently in this context, and these two exceptions have to be resolved before cooperative handling starts at the level of this action 5. 3 Exception Handling in Systems with Cooperative and Competitive Concurrency Conceptually, exception handling in CA actions [25] (Fig. 8) is very similar to that in atomic actions [4] all action participants are involved in cooperative handling of any internal exception, internal exceptions raised concurrently are resolved, external exceptions are explicitly propagated by action participants, etc. Fig. 9) The main ....

Randell, B., Romanovsky, A., Stroud, R.J., Xu, J., Zorzo, A.F.: Coordinated Atomic Actions: from Concept to Implementation. Computing Dept., University of Newcastle upon Tyne. Technical Report 595 (1997)

....applied directly to implement reliable systems (see [8] However, sometimes it is necessary to adopt a more restricted form of exception handling in which case our framework can be used to implement a more constrained programming abstraction with stronger exception handling semantics. CA actions [9, 10] are an example of such an abstraction. In this section, we describe the exception handling semantics of CA actions and explain how a CA action mechanism can be implemented using our framework. However, it would equally be possible to use our framework to implement other abstractions such as ....

....one action at a time. Actions in DisCo describe the transformation of the system state represented by the participants. DisCo does not allow actions to be nested and does not consider the possibility of failures during the execution of actions. Recently, the Coordinated Atomic (CA) action concept [9, 10] has been introduced as a unified approach to structuring complex concurrent activities and supporting error recovery between multiple interacting objects in an objectoriented system. Although the CA action mechanism is a very good approach for providing multiparty interactions in a dependable ....

B. Randell, A. Romanovsky, R. J. Stroud, J. Xu, and A. F. Zorzo. "Coordinated Atomic Actions: from Concept to Implementation". Department of Computing Science, Technical Report TR595, University of Newcastle upon Tyne, 1997.

....one action at a time. Actions in DisCo describe the transformation of the system state represented by the participants. DisCo does not allow actions to be nested and do not consider the possibility of failures during the execution of actions. Recently, the Coordinated Atomic (CA) action concept [14, 15] has been introduced as a unified approach to structuring complex concurrent activities and supporting error recovery between multiple interacting objects in an object oriented system. Although the CA action mechanism is a very good approach for providing multiparty interactions in a dependable ....

B. Randell, A. Romanovsky, R. J. Stroud, J. Xu, and A. F. Zorzo. "Coordinated Atomic Actions: from Concept to Implementation". Department of Computing Science, Technical Report TR595, University of Newcastle upon Tyne, 1997.

....sides, a black rectangle for each method. Labelled arrows between places and internal transitions or between places and methods give the flow relations (what is consumed and what is added to a place when an internal transition or a method is fired) 2. 2 Coordinated Atomic Actions The CA action [1, 8] concept was introduced as a unified approach for structuring complex concurrent activities and supporting error recovery of multiple interacting objects in an object oriented system. This paradigm provides a conceptual framework for dealing with both kinds of concurrency (cooperative and ....

B. Randell, A. Romanovsky, R. J. Stroud, J. Xu, and A. F. Zorzo. Coordinated Atomic Actions: from Concept to Implementation. Computing Dept., University of Newcastle upon Tyne, TR 595, 1997. http://www.cs.ncl.ac.uk/research/trs/papers/595.ps

....to sequential processes. Moreover, a set of method calls can be concurrently performed on the same object. The step semantics of CO OPN 2 allows the expression of true concurrency which is not possible using an interleaving semantics. 1. 2 Coordinated Atomic Actions The Coordinated Atomic action [1, 2] concept was introduced as a unified approach for structuring complex concurrent activities and supporting error recovery between multiple interacting objects in an object oriented system. This paradigm provides a conceptual framework for dealing with both kinds of concurrency (cooperative and ....

B. Randell, A. Romanovsky, R. J. Stroud, J. Xu, and A. F. Zorzo. Coordinated Atomic Actions: from Concept to Implementation. http://www.cs.ncl.ac.uk/research/trs/papers/595.ps Computing Dept., University of Newcastle upon Tyne, TR 595, 1997.

....firing of several methods. An HML formula is satisfied by the model of a CO OPN 2 specification if the sequence of events defined by the formula correspond to a possible sequence of events of the model of the specification. 2.3. Dependable Design: Coordinated Atomic Actions The CA action [1, 8] concept was introduced as a unified approach for structuring complex concurrent activities and supporting error recovery of multiple interacting objects in an object oriented system. This paradigm provides a conceptual framework for dealing with both kinds of concurrency (cooperative and ....

....how the exception ReactionException would be handled, i.e. the two integers are stored in the queue of the participant performing the consumer role. Any exception raised during the handling of an exception will cause the CA action mechanism to raise a failure exception to the enclosing context [8]. private void consumer(Participant p) throws Exception f Exception exception = null; Integer num1, num2; int sum; try f num1 = Integer) p1Channel.receive( num2 = Integer) p2Channel.receive( sum = num1.intValue( num2.intValue( p.remoteQueuePut(sum) g catch (Exception e) f ....

B. Randell, A. Romanovsky, R. J. Stroud, J. Xu, and A. F. Zorzo: `Coordinated atomic actions: from concept to implementation. ' Technical report TR 595, Department of Computing Science, University of Newcastle upon Tyne, 1997. (http://www.cs.ncl.ac.uk/research/trs/papers/595.ps)

....with other actions concurrently, must be atomic and individually responsible for their own integrity. In a sense CA actions can be seen as a disciplined approach to using multi threaded nested transactions, and to providing them with well structured exception handling. For further details see [Randell et al. 1997]. Figure 1 shows a simple example in which two threads enter a CA action asynchronously through different entry points. Within the CA action the threads communicate with each other and cooperate in pursuit of some common goal. However, during the execution of the CA 6 action, an exception e is ....

B. Randell, A. Romanovsky, R. Stroud, J. Xu and A.F. Zorzo, "Coordinated Atomic Actions: from Concept to Implementation," Technical Report, Department of Computer Science, University of Newcastle upon Tyne, no.595, 1997.

....studies we use in this paper, and describe how we designed both systems using CA actions. In Section 4 we describe an object oriented framework for implementing CA actions in Java. Finally Section 5 draws some conclusions. 1. 1 Coordinated Atomic Actions The Coordinated Atomic (CA) action concept [3] [4] is a unified approach to structuring complex concurrent activities and supporting error recovery between multiple interacting objects in an object oriented system. This paradigm provides a conceptual framework for supporting both cooperative and competitive concurrency and for achieving fault ....

....one manager object, a set of role objects, a set of local objects, and a set of external objects. The CA action mechanism is responsible for managing synchronous action entry and exit, global exception handling, recovery, consistency and atomicity of external and local objects, and so on [3]. We have implemented both shared local object action object manager the roles under control connects the controller and role 1 object from other CA Actions external object atomic host 5 host 1 CA action role uses this object private local object shows that the role 2 object host 3 host 6 ....

[Article contains additional citation context not shown here]

B. Randell, A. Romanovsky, R. J. Stroud, J. Xu, and A. F. Zorzo. "Coordinated Atomic Actions: from Concept to Implementation". Department of Computing Science, TR595, University of Newcastle upon Tyne, UK.

....atomicity, consistency, isolation and durability. This mechanism allows processes to access resources (objects, files, DBs, servers) as if they were at their exclusive disposal, and although transactional support allows concurrent access, this is transparent for processes. The CA action [Xu 95, Randell 97] concept was introduced as a unified approach to structuring complex concurrent activities and supporting error recovery between multiple interacting objects in an OO system. This paradigm provides a conceptual framework for dealing with both kinds of concurrency (cooperative and competitive ....

....detail of the latter ones. A reason to adopt this differentiation is that, at the initial stages of the software lifecycle it is too early to refer to notions like operations on objects, syntactic threads, and run time abstractions, which make part of the thread definition in a CA action [Randell 97] Instead, at the early stages of a lifecycle there is a need to represent objects and their cooperations in terms of properties without getting into the detail how these will be implemented. The motivation for adopting CA actions, as an abstraction for modelling cooperations between objects, ....

B. Randell, A. Romanovsky, R.J. Stroud, J. Xu, and A.F. Zorzo. Coordinated Atomic Actions: from Concept to Implementation. Technical Report 595. Department of Computing Science. University of Newcastle upon Tyne, UK. 1997.

....to extract from the specification of an object those issues which are related with its collaborative activities, thus avoiding that a specification of a cooperation be scattered among the specifications of the objects. CO actions are a variant of Coordinated Atomic Actions (CA actions) Xu 95, Randell 97] which are design mechanisms for structuring complex concurrent activities and supporting error recovery between multiple interacting objects in an OO system. The main intent behind the cooperative object oriented approach for software development is to use modified versions of structuring ....

....all its participants) into a know consistent state (corresponding to the exceptional action pre conditions) and to propagate an external exception to higher level (containing) FeedBelt object within which it will be signalled as an object level exception. Existing distributed CA actions schemes [Randell 97] developed for Ada 95 and Java can be used to support programs modelling on the later phases (including their execution) 5. Conclusions In spite of the fact that there are still problems related to using exception handling in the later phases of the life cycle [Miller 97] we consider that this ....

B. Randell, A. Romanovsky, R.J. Stroud, J. Xu, A.F. Zorzo. Co-ordinated Atomic Actions: from Concept to Implementation. Technical Report 595. Dept. of Computing Science. University of Newcastle. UK. 1997.

No context found.

B. Randell, A. Romanovsky, R. Stroud, J. Xu, and A.F. Zorzo, "Coordinated Atomic Actions: from Concept to Implementation," Technical Report, Department of Computer Science, University of Newcastle upon Tyne, no.595, 1997.

....developed in Java, a language that provides explicit support for concurrent and cooperative programming. The detailed problems tackled and results obtained from our case studies and prototypes are however beyond the intended scope of this paper and will be examined in further technical reports [Randell et al. 1997]. 7 Concluding Remarks Real world applications contain many examples of cooperative concurrent activities, but the widely used objects and (trans)actions model does not provide appropriate support for cooperative concurrency. Generalized transaction schemes provide only limited support for ....

B. Randell, A. Romanovsky, R.J. Stroud, J. Xu and A.F. Zorzo, "Coordinated Atomic Actions: From concept to implementation," submitted to IEEE Trans. Computers, 1997.

....studies we use in this paper, and describe how we designed both systems using CA actions. In Section 4 we describe an object oriented framework for implementing CA actions in Java. Finally Section 5 draws some conclusions. 1. 1 Coordinated Atomic Actions The Coordinated Atomic (CA) action concept [Randell et al. 1997] [Xu et al. 1995] is a unified approach to structuring complex concurrent activities and supporting error recovery between multiple interacting objects in an object oriented system. This paradigm provides a conceptual framework for supporting both cooperative and competitive concurrency and for ....

....one manager object, a set of role objects, a set of local objects, and a set of external objects. The CA action mechanism is responsible for managing synchronous action entry and exit, global exception handling, recovery, consistency and atomicity of external and local objects, and so on [Randell et al. 1997]. We have implemented both of the case studies described in Sections 2 and 3 using the Java language [Arnold Gosling 1996] an object oriented language that has been widely used to develop distributed applications over the Internet. We use the Java Remote Method Invocation (RMI) API in order to ....

[Article contains additional citation context not shown here]

B. Randell, A. Romanovsky, R. J. Stroud, J. Xu, and A. F. Zorzo. "Coordinated Atomic Actions: from Concept to Implementation". Department of Computing Science, TR595, University of Newcastle upon Tyne, UK. 1997. http://www.cs.ncl.ac.uk/research/trs/papers/595.ps

No context found.

B. Randell, A. Romanovsky, R. Stroud, J. Xu and A.F. Zorzo, "Coordinated Atomic Actions: from Concept to Implementation," Technical Report, Department of Computer Science, University of Newcastle upon Tyne, no.595, 1997.

No context found.

B. Randell, A. Romanovsky, R. J. Stroud, J. Xu, and A. F. Zorzo. Coordinated Atomic Actions: from Concept to Implementation. Research Report TR 595, University of Newcastle upon Tyne, Newcastle upon Tyne, UK, 1997.

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B. Randell, A. Romanovsky, R.J. Stroud, J. Xu, and A.F. Zorzo. Coordinated Atomic Actions: from Concept to Implementation. Submitted to Special Issue of IEEE Transactions on Computers, 1997.

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B. Randell, A. Romanovsky, R. J. Stroud, J. Xu, and A. F. Zorzo. Coordinated atomic actions: from concept to implementation. Technical Report TR 595, Computing Dept., University of Newcastle upon Tyne, 1997.

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