Formalization of discovery and communication mechanisms of Tuple Space based Mobile Middleware for underlying unreliable infrastructure

Middleware Reconfiguration Relying on Formal Methods

Abstract: Adaptive middleware is a software for developing and executing distributed applications and can be reconfigured at runtime without its complete stop. The need of reconfiguration is usually triggered by changes in application's requirements and environmental conditions, to fix bugs or to extend the middleware's functionality. The development of an adaptive middleware still being a challenge due to the complexity of dealing with adaptation issues, such as how, when and where to reconfigure the middleware. Existing solutions to build adaptive middleware concentrate on the use of software mechanisms like aspect oriented programming and computational reflection to face the issues behind the reconfiguration. In this paper, we propose to reconfigure the middleware by moving adaptation decisions and actions from the middleware to an external and formally-based element. The whole adaptation process is performed based on the behavioural analysis of the middleware execution trace. In order to evaluate the proposed approach, we carried experimental experiments to check the effectiveness of the proposed adaptation mechanism and measure the overhead caused by the proposed adaptation mechanism.

Consistent Coordination Decoupling in Tuple Space Based Mobile Middleware: Design and Formal Specifications

Abstract: Tuple Space based Mobile Middleware (TSMM), with tuple space as its coordination medium, provides multiple decoupled behaviors for coordinating interactions between different agents of supported applications However, maintaining consistency in TSMM is a challenging problem, considering its underlying infrastructure with unpredictable host mobility, sporadic network dynamics, and unreliability in communication links Existing TSMM maintains consistency by coupling interacting agents, which in turn reduces decoupling abilities of TSMM, thereby restricting development of robust and flexible applications This paper addresses consistency problems while decoupling agent interactions in TSMM, which renders complete decoupling of interactions It proposes mechanisms to resolve consistency problems in a fully-decoupled TSMM Both OUT-consistency and IN-consistency problems are handled in proposed mechanisms This paper also suggests an approach for formalizing proposed consistency mechanisms in TSMM in order to appropriately analyze reliability and robustness of TSMM as coordination platform for mobile applications Formalization is carried out using Mobile UNITY

The many faces of publish/subscribe

Abstract: Well adapted to the loosely coupled nature of distributed interaction in large-scale applications, the publish/subscribe communication paradigm has recently received increasing attention. With systems based on the publish/subscribe interaction scheme, subscribers register their interest in an event, or a pattern of events, and are subsequently asynchronously notified of events generated by publishers. Many variants of the paradigm have recently been proposed, each variant being specifically adapted to some given application or network model. This paper factors out the common denominator underlying these variants: full decoupling of the communicating entities in time, space, and synchronization. We use these three decoupling dimensions to better identify commonalities and divergences with traditional interaction paradigms. The many variations on the theme of publish/subscribe are classified and synthesized. In particular, their respective benefits and shortcomings are discussed both in terms of interfaces and implementations.

Generative communication in Linda

Abstract: Generative communication is the basis of a new distributed programming langauge that is intended for systems programming in distributed settings generally and on integrated network computers in particular. It differs from previous interprocess communication models in specifying that messages be added in tuple-structured form to the computation environment, where they exist as named, independent entities until some process chooses to receive them. Generative communication results in a number of distinguishing properties in the new language, Linda, that is built around it. Linda is fully distributed in space and distributed in time; it allows distributed sharing, continuation passing, and structured naming. We discuss these properties and their implications, then give a series of examples. Linda presents novel implementation problems that we discuss in Part II. We are particularly concerned with implementation of the dynamic global name space that the generative communication model requires.

Parallel Program Design: A Foundation

Abstract: Introducing a new hobby for other people may inspire them to join with you. Reading, as one of mutual hobby, is considered as the very easy hobby to do. But, many people are not interested in this hobby. Why? Boring is the reason of why. However, this feel actually can deal with the book and time of you reading. Yeah, one that we will refer to break the boredom in reading is choosing parallel program design a foundation as the reading material.

LIME: A coordination model and middleware supporting mobility of hosts and agents

Abstract: LIME (Linda in a mobile environment) is a model and middleware supporting the development of applications that exhibit the physical mobility of hosts, logical mobility of agents, or both. LIME adopts a coordination perspective inspired by work on the Linda model. The context for computation, represented in Linda by a globally accessible persistent tuple space, is refined in LIME to transient sharing of the identically named tuple spaces carried by individual mobile units. Tuple spaces are also extended with a notion of location and programs are given the ability to react to specified states. The resulting model provides a minimalist set of abstractions that facilitates the rapid and dependable development of mobile applications. In this article we illustrate the model underlying LIME, provide a formal semantic characterization for the operations it makes available to the application developer, present its current design and implementation, and discuss lessons learned in developing applications that involve physical mobility.