Assessing the Reliability and Cost of Web and Grid Orchestrations

Stewart, A L; Clint, Maurice; Harmer, Terence J.; Kilpatrick, Peter; Perrott, Ronald H.; Gabarró, Joaquim

doi:10.1109/ares.2008.39

Cited by 5 publications

(4 citation statements)

References 6 publications

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“…And, the availability of an Orc description makes possible the analysis of system variants with respect to cost and reliability using techniques described in [15].…”

Section: Resultsmentioning

confidence: 99%

Management in Distributed Systems: A Semi-formal Approach

Aldinucci

Danelutto

Kilpatrick

2007

Euro-Par 2007 Parallel Processing

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Abstract. The reverse engineering of a skeleton based programming environment and redesign to distribute management activities of the system and thereby remove a potential single point of failure is considered. The Orc notation is used to facilitate abstraction of the design and analysis of its properties. It is argued that Orc is particularly suited to this role as this type of management is essentially an orchestration activity. The Orc specification of the original version of the system is modified via a series of semi-formally justified derivation steps to obtain a specification of the decentralized management version which is then used as a basis for its implementation. Analysis of the two specifications allows qualitative prediction of the expected performance of the derived version with respect to the original, and this prediction is borne out in practice.

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“…And, the availability of an Orc description makes possible the analysis of system variants with respect to cost and reliability using techniques described in [15].…”

Section: Resultsmentioning

confidence: 99%

Management in Distributed Systems: A Semi-formal Approach

Aldinucci

Danelutto

Kilpatrick

2007

Euro-Par 2007 Parallel Processing

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“…We have found only very few non experimental papers dealing with our topic of interest. In [24] the study of orchestrations in unreliable environments with known probabilities has been undertaken using finite Markov chains. Here we develop an alternative approach based on probabilistic environments.…”

Section: Elementaryorcmentioning

confidence: 99%

The computational complexity of QoS measures for orchestrations

2017

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We consider Web services defined by orchestrations in the Orc language and two natural quality of services measures, the number of outputs and a discrete version of the first response time. We analyse first those subfamilies of finite orchestrations in which the measures are well defined and consider their evaluation in both reliable and probabilistic unreliable environments. On those subfamilies in which the QoS measures are well defined, we consider a set of natural related problems and analyse its computational complexity. In general our results show a clear picture of the difficulty of computing the proposed QoS measures with respect to the expressiveness of the subfamilies of Orc. Only in few cases the problems are solvable in polynomial time pointing out the computational difficulty of evaluating QoS measures even in simplified models.

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“…Therefore, the Angel-Daemon game associated to a uncertainty profile for a given Orc expression E, allows to analyse the behaviour of orchestrations over unreliable environments. For such an analysis, the risk profile 1 concept [44] has been introduced, where a distinction is made between risk and uncertainty [106].…”

Section: Angel-daemon Games and Web Orchestrationsmentioning

confidence: 99%

“…-The behaviour of an orchestration under failures can also be studied using a probabilistic approach [106].…”

Section: Morphisms In Gamesmentioning

confidence: 99%

The Complexity of angel-daemons and game isomorphism

García Chacón

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The analysis of the computational aspects of strategic situations is a basic field in Computer Sciences. Two main topics related to strategic games have been developed. First, introduction and analysis of a class of games (so called angel/daemon games) designed to asses web applications, have been considered. Second, the problem of isomorphism between strategic games has been analysed. Both parts have been separately considered. Angel-Daemon Games A service is a computational method that is made available for general use through a wide area network. The performance of web-services may fluctuate; at times of stress the performance of some services may be degraded (in extreme cases, to the point of failure). In this thesis uncertainty profiles and Angel-Daemon games are used to analyse servicebased behaviours in situations where probabilistic reasoning may not be appropriate. In such a game, an angel player acts on a bounded number of ¿angelic¿ services in a beneficial way while a daemon player acts on a bounded number of ¿daemonic¿ services in a negative way. Examples are used to illustrate how game theory can be used to analyse service-based scenarios in a realistic way that lies between over-optimism and over-pessimism. The resilience of an orchestration to service failure has been analysed - here angels and daemons are used to model services which can fail when placed under stress. The Nash equilibria of a corresponding Angel-Daemon game may be used to assign a ¿robustness¿ value to an orchestration. Finally, the complexity of equilibria problems for Angel-Daemon games has been analysed. It turns out that Angel-Daemon games are, at the best of our knowledge, the first natural example of zero-sum succinct games. The fact that deciding the existence of a pure Nash equilibrium or a dominant strategy for a given player is Sp 2-complete has been proven. Furthermore, computing the value of an Angel-Daemon game is EXP-complete. Thus, matching the already known complexity results of the corresponding problems for the generic families of succinctly represented games with exponential number of actions. Game Isomorphism The question of whether two multi-player strategic games are equivalent and the computational complexity of deciding such a property has been addressed. Three notions of isomorphisms, strong, weak and local have been considered. Each one of these isomorphisms preserves a different structure of the game. Strong isomorphism is defined to preserve the utility functions and Nash equilibria. Weak isomorphism preserves only the player preference relations and thus pure Nash equilibria. Local isomorphism preserves preferences defined only on ¿close¿ neighbourhood of strategy profiles. The problem of the computational complexity of game isomorphism, which depends on the level of succinctness of the description of the input games but it is independent of the isomorphism to consider, has been shown. Utilities in games can be given succinctly by Turing machines, boolean circuits or boolean formulas, or explicitly by tables. Actions can be given also explicitly or succinctly. When the games are given in general form, an explicit description of actions and a succinct description of utilities have been assumed. It is has been established that the game isomorphism problem for general form games is equivalent to the circuit isomorphism when utilities are described by Turing Machines; and to the boolean formula isomorphism problem when utilities are described by formulas. When the game is given in explicit form, it is has been proven that the game isomorphism problem is equivalent to the graph isomorphism problem. Finally, an equivalence classes of small games and their graphical representation have been also examined.

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Assessing the Reliability and Cost of Web and Grid Orchestrations

Abstract: Abstract

Cited by 5 publications

References 6 publications

Management in Distributed Systems: A Semi-formal Approach

Management in Distributed Systems: A Semi-formal Approach

The computational complexity of QoS measures for orchestrations

The Complexity of angel-daemons and game isomorphism

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