A Formal Methodology for the Specification of Distributed Systems From an Object Perspective.

Distributed computing systems are systems in which multiple processors run independently by communicating with each other. The design of distributed systems is difficult to achieve as the execution patterns of distributed system are typically more complex than those of non-distributed computing systems. The application of object-oriented techniques to the design of distributed systems has the potential to increase the power of modeling and computing. A formal methodology which includes a specification language, developed from an object perspective, for the development of distributed systems is presented. The formal specification language, DOSL (Distributed Object-based Specification Language), represents the specification of distributed systems from an object perspective. DOSL has a hybrid format which combines the property-oriented approach and the model-oriented approach. In particular, it has strong features for message passing specification. The semantics of DOSL is defined formally by two operational semantics methods: transition systems and Petri nets. In addition, a formal object-based methodology for the specification of distributed systems is given. The methodology presents a framework for using the DOSL specification language and includes an integrated formalized method for identification of objects, their operations and behaviors from multiple modeling formats. The implementation of the methodology is supported by assistance with a knowledge base

A Technique for Distributed Systems Specification

In this paper we show how an object-oriented specification language is usefvl for the specification of distributed systems. The main constructors in this language are the objects. An object consists of a state, a behaviour and a set of transition rules between states. The specification is composed by three sections: definition of algebraic data types to represent the domain of object attributes, definition of classes that group objects with common features, and definition of relationships among classes. We show two possible styles for defining the behaviour of objects, in one hand we use a transition system (state oriented) and in the other hand we use an algebraic model of processes description (constraint oriented). We illustrate the paper with the specification of the dining philosophers problem, a typical example in distributed programming

Requirements analysis of the VoD application using the tools in TRADE

This report contains a specification of requirements for a video-on-demand (VoD) application developed at Belgacom, used as a trial application in the 2RARE project. The specification contains three parts: an informal specification in natural language; a semiformal specification consisting of a number of diagrams intended to illustrate the informal specification; and a formal specification that makes the requiremants on the desired software system precise. The informal specification is structured in such a way that it resembles official specification documents conforming to standards such as that of IEEE or ESA. The semiformal specification uses some of the tools in from a requirements engineering toolkit called TRADE (Toolkit for Requirements And Design Engineering). The purpose of TRADE is to combine the best ideas in current structured and object-oriented analysis and design methods within a traditional systems engineering framework. In the case of the VoD system, the systems engineering framework is useful because it provides techniques for allocation and flowdown of system functions to components. TRADE consists of semiformal techniques taken from structured and object-oriented analysis as well as a formal specification langyage, which provides constructs that correspond to the semiformal constructs. The formal specification used in TRADE is LCM (Language for Conceptual Modeling), which is a syntactically sugared version of order-sorted dynamic logic with equality. The purpose of this report is to illustrate and validate the TRADE/LCM approach in the specification of distributed, communication-intensive systems

A hierarchical distributed control model for coordinating intelligent systems

A hierarchical distributed control (HDC) model for coordinating cooperative problem-solving among intelligent systems is described. The model was implemented using SOCIAL, an innovative object-oriented tool for integrating heterogeneous, distributed software systems. SOCIAL embeds applications in 'wrapper' objects called Agents, which supply predefined capabilities for distributed communication, control, data specification, and translation. The HDC model is realized in SOCIAL as a 'Manager'Agent that coordinates interactions among application Agents. The HDC Manager: indexes the capabilities of application Agents; routes request messages to suitable server Agents; and stores results in a commonly accessible 'Bulletin-Board'. This centralized control model is illustrated in a fault diagnosis application for launch operations support of the Space Shuttle fleet at NASA, Kennedy Space Center

Automatic Generation of Distributed System Simulations from UML

Nowadays, an object-oriented approach is commonly used for building computer systems. The benefits of the object-oriented method, such as scalability, stability and reusability, make this method suitable for building complex systems, including those in the distributed system area. A distributed system application usually needs to satisfy quite stringent requirements such as reliability, availability, security, etc. and the cost of building such an application will be quite high. It is therefore desirable to be able to predict the performance of the proposed system before the construction begins. In order to do this, it is important to evaluate the requirements of the new system and translate them into a specification (design). The design process helps the system developers to understand the requirements better as well as to avoid misconceptions about the system. From the specification, a simulation program can be built to mimic the execution of the proposed system. The simulation run provides some data about the states of the system and from these data, the performance of the system can be predicted and analysed. UML (Unified Modeling Language) is one example of the object-oriented design methods that has been widely used for specifying system requirements. There are also some object-oriented simulation languages/packages available, for example, SIMULA or C++SIM package, but it is often difficult to transform the system’ s requirements into a simulation program without sound knowledge of some simulation techniques. On top of that, a new simulation program needs to be built each time for different systems, which can be quite tedious. The currently available UML tools do not provide a feature to generate simulation programs automatically from UML specifications. In this paper, we describe a tool for constructing simulation programs in a generic way, based on a simple specification (preferably in a UML notation) by identifying the simulation components and their structure

Engineering telecommunication services with SDL

If formal techniques are to be more widely accepted then they should evolve as current software engineering approaches evolve. Current techniques in the development of distributed systems use interface definition languages (IDLs) as a basis for the underlying communication and also as an abstraction tool. Object-oriented technologies [6] and the idea of engineering software through frameworks [5] are also widely accepted approaches in developing software. In this paper we show how the formal specification language SDL and associated tool support have been applied in the TOSCA1 project to engineer telecommunication services using these current techniques

A Specification Environment That Supports the Prototyping of Distributed Systems Using an Object-Oriented Model.

High-speed computer networking, interactive service, and incremental growth for computing are some of the motivations for developing a distributed system. Despite the inherent benefits of a distributed system, the development of software support is more difficult for distributed systems than for sequential systems. In either case, difficulties may arise from the communication problems between two groups of people with different backgrounds trying to formulate requirements for the system. This process depends on feedback and may take many iterations to converge. Customers can usually recognize the features they need when they start using a system, which makes prototyping an important tool in requirement analysis. Many prototyping goals, objectives, and approaches are possible. Executable formal specifications are the most attractive ones. This unification of specification and prototyping by having code generators has advantages of providing consistency and prototyping at higher levels of abstraction. Thus, a methodology for executing the DOSL (Distributed Object-based Specification Language) is defined and a prototype system is developed. DOSL is extended as a new formal distributed object-oriented specification language, DOSL-II. DOSL-II is object-oriented rather than object-based, and includes class, inheritance, simple I/O, stream I/O, concurrent I/O, and new constructs for object communication

A distributed object-oriented graphical programming system

technical reportThis report presents the design of a distributed parallel object system (DPOS) and its implementation using a graphical editing interface. DPOS brings together concepts of object-oriented programming and graphical programming with aspects of modern functional languages. Programs are defined as networks of active processes called "Process Objects" and interconnecting communications lines. These active objects are independent single threaded programs that employ much of the modularity, encapsulation of function, and encapsulation of data found in sequential object-oriented programming. The system defines a clear and simple approach to generating and managing parallelism and interprocess communication in a distributed parallel environment. DPOS contributes several new solutions to the problems of distributed parallel programming that are improvements over existing systems. The key improvements of this system include: a more complete and versatile means of dynamic process creation; the specification of complex network topologies in an intuitively clear and understandable way; seperation of the management of parallelism from the definition of computation; automatic resolution of low level critical section issues; the ability to design and develop separate processes as traditional single threaded programs; the encapsulation and incremental development of programs subnetworks; application of graphical programming concepts to high level programming

Discrete Simulation of Distributed Systems - Performance Evaluation of a Notification Channel Federation

This paper presents how discrete simulation can be used for performance evaluation of distributed systems. With this methodology it is not needed to implement the system itself, only a model of proper specification is required. Simulation models for distributed systems can be easily adopted from other models which are already used in network simulations with good results. The tool that supports our measurements is a powerful telecom simulation platform, a simulations development environment that supports object-oriented programming. The model used for demonstration represents a notification channel federation including an arbitrary number of event suppliers and event consumers connected to a scalable network. Performance is evaluated for various configurations, and results are presented

A survey on quality of service support on middelware-based distributed messaging systems used in multi agent systems

The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-642-19934-9_10Messaging systems are widely used in distributed systems to hide the details of the communications mechanism to the multi agents systems. However, the Quality of Service is treated in different way depending on the messaging system used. This article presents a review and further analysis of the quality of service treatment in the mainly messaging systems used in distributed multi agent systems. The review covers the issues related to the purpose of the functions provided and the scope of the quality of service offered by every messaging system. We propose ontology for classifying and decide which parameters are relevant to the user. The results of the analysis and the ontology can be used to select the most suitable messaging system to distributed multi agent architecture and to establish the quality of service requirements in a distributed system.The study described in this article is a part of the coordinated project SIDIRELI: Distributed Systems with Limited Resources. Control Kernel and Coordination. Education and Science Department, Spanish Government and European FEDER found. CICYT: MICINN: DPI2008-06737-C02-01/02.Poza-Lujan, J.; Posadas-Yagüe, J.; Simó Ten, JE. (2011). A survey on quality of service support on middelware-based distributed messaging systems used in multi agent systems. En International Symposium on Distributed Computing and Artificial Intelligence. Springer. 77-84. https://doi.org/10.1007/978-3-642-19934-9_10S7784Gaddah, A., Kunz, T.: A survey of middleware paradigms for mobile computing. Technical Report SCE-03-16. Carleton University Systems and Computing Engineering (2003)Foundation for Intelligent Physical Agents, http://www.fipa.org/Java Message Service Specification, http://java.sun.com/products/jms/docs.htmlCommon Object Request Broker Architecture, http://www.corba.org/Data Distribution Service, http://portals.omg.org/dds/Java Agent DEvelopment Framework, http://jade.tilab.com/Agent Oriented Software Pty Ltd., JACK Intelligent Agents: User Guide (1999)Nwana, H., Ndumu, D., Lee, L., Collis, J.: ZEUS: A tool-kit for building distributed multi-agent systems. Applied Artifical Intelligence Journal 13(1), 129–186 (1999)Perdikeas, M.K., Chatzipapadopoulos, F.G., Venieris, I.S., Marino, G.: Mobile Agent Standards and Available Platforms. Computer Networks Journal, Special Issue on ’Mobile Agents in Intelligent Networks and Mobile Communication Systems’ 31(10) (1999)Perrone, P.J., Chaganti, K.: J2EE Developer’s Handbook. Sam’s Publishing, Indianapolis (2003)Apache ActiveMQ, http://activemq.apache.org/IBM WebSphere MQSeries, http://mqseries.net/Object Management Group, http://www.omg.org/RTI Data Distribution Service. RTI corp., http://www.rti.com/OpenSplice DDS. PrismTech Ltd., http://www.prismtech.comVogel, A., Kerherve, B., von Bochmann, G., Gecsei, J.: Distributed Multimedia and QoS: A Survey. IEEE Multimedia 2(2), 10–19 (1995)Crawley, E., Nair, R., Rajagopalan, B.: RFC 2386: A Framework for QoS-based Routing in the Internet. IETF Internet Draft, 1–37 (1998)Foundation for Intelligent Physical Agents. FIPA Quality of Service Ontology Specification. Doc: SC00094A (2002)Sun Microsystems, Inc. Java(TM) Message Service Specification Final Release 1.1 (2002)Object Management Group (OMG). The Common Object Request Broker Architecture and Specification. CORBA 2.4.2 (2001