scholarly journals CONCEPTUAL REPRESENTATIONS AND MODIFICATIONS OF PETRI NETS FOR APPLICATIONS IN THE AREA OF SYNTHESIS OF A FUNCTIONAL ARCHITECTURE OF DISTRIBUTED COMPUTATIONAL SYSTEMS WITH VARIABLE STRUCTURE

2019 ◽  
Vol 22 (6) ◽  
pp. 143-167
Author(s):  
S. A. Zinkin ◽  
Mustafa Sadeq Jaafar ◽  
N. S. Karamysheva
Keyword(s):  
Distributed Computing ◽  
Petri Nets ◽  
Computer Network ◽  
Variable Structure ◽  
Semantic Networks ◽  
Conceptual Graphs ◽  
Network Computing ◽  
Functional Architecture ◽  
Distributed Computing Systems ◽  
Computing Systems

Background. The object of the research is the functional architecture of distributed computing systems with a variable (reconfigurable) structure characteristic of hybrid systems of cloud-network (grid) type. Despite the fact that Petri nets have long been studied both theoretically and practically, the methods of their interpretation continue to develop intensively. At present, the problem of embedding Petri nets in the architecture of distributed network applications used to implement global computing in modern mixed cloud, grid and cluster systems has not been sufficiently studied. It is shown that in modern studies, Petri nets are used mainly in the simulation of discrete systems and processes, and not as the basis for formalized specifications in the development of distributed applications. In this regard, the interpretation of Petri nets in applications to the functional architecture of distributed computing systems with a variable structure based on the network software of the intermediate class (middleware class) is relevant. The aim of the work was the integration of graphical representations of conceptual graphs, semantic networks, scenarios and Petri nets, which made it possible to create effective tools with graphical support for designing a functional architecture of distributed computing systems with a variable structure and, in particular, a cloudy architecture of the NCaaSoD type - Network Computing as a Service on Demand (network computing as a cloud service at the request of the user).Materials and methods. The conceptual models of distributed processes that are a graphical interpretation of the first-order predicate calculus are used. Conceptual graphs for distributed Petri nets of mixed type have been proposed, which allow describing computation processes in global computational networks with a view to their subsequent implementation. Results. Based on the integration of graphical representations of conceptual graphs, semantic networks, scenarios and Petri nets, conceptual representations of distributed reconfigurable Petri nets are proposed, allowing them to be directly integrated into the architecture of the computer network.Results. New conceptual-behavioral models based on conceptual graphs of distributed Petri nets have been proposed to determine the system and functional architectures of distributed computing systems with a variable structure provided to the user as a hybrid cloud-based network service; these models are distinguished by the possibility of operational reconfiguration and immediate execution.Conclusion. A method was proposed and formalized for embedding conceptual Petri nets into the architecture of cloud-networked computer systems such as NCaaSoD — network (cloud) computing as a service organized at the user's request. The rules for obtaining relations of connectivity between the positions and transitions of the Petri net, placed on the nodes of the physical computer network, are proposed.

scholarly journals DEVELOPMENT OF INFORMATION AND COMMUNICATION INFRASTRUCTURE OF DISTRIBUTED COMPUTING SYSTEMS BASED ON THE CONCEPT "THE NETWORK IS THE COMPUTER"

2018 ◽  
Vol 22 (4) ◽  
pp. 75-93 ◽  
Author(s):  
S. A. Zinkin ◽  
Mustafa Sadeq Jaafar
Keyword(s):  
Distributed Computing ◽  
Cloud Service ◽  
Third Party ◽  
Hybrid Cloud ◽  
Network Computing ◽  
Functional Architecture ◽  
Distributed Computing Systems ◽  
Computing Systems ◽  
Network Computer ◽  
Meta Information

The concept "network is a computer" that has been further developed in the form of a paradigm of cloud applications that have the properties of "multi-lease"and "live" database migration is considered. Of particular interest in this regard is the development of a middleware for large reconfigurable clustered server systems as part of the support of the "big data" concept. Therefore, an approach is being developed to design a reconfigurable and parametrically tuned system and functional architecture of distributed computing systems. In some cases, the implementation of this approach can provide increased efficiency and cost reduction of large software and hardware systems. The article categorizes distributed computing systems when taking into account the specifics of cloud, grid, cluster and other types of communal, parallel and distributed computations. It is recommended to use as a basis hybrid architectures that combine the positive properties of cloud, grid and cluster distributed computing systems. The concept of organization of distributed network computing as services, implemented at the client's request, is developed. A network model that describes the work of a hybrid cloud grid system with third-party auditors and cloud service providers, is proposed. A distinctive feature of the proposed model is that when implementing as a concept NCaaSoD (network architecture as a service on the user's request) before the execution of a request, such as Upload (uploading data to the cloud), meta-information about available resources in order to further create a virtual cluster from the available nodes of the network of the cloud service provider, and before requesting the download type request (request information from the cloud), information is requested about the nodes that store the results. Meta-information can be obtained not only from a third-party auditor, but also from a remote monitoring service. To further develop the proposed concepts to real technology, it is advisable to develop a methodology for transforming conceptual models of the system and functional architecture into specifications suitable for the formation of virtual topologies of a network computer such as NCaaSoD in a hybrid cloud environment.

scholarly journals Research and Organization of Priority Modes in a Network Distributed Computing System with Cloud Service Architecture

2019 ◽  
Vol 23 (2) ◽  
pp. 153-173
Author(s):  
M. Sadeq Jaafar
Keyword(s):  
Distributed Computing ◽  
Petri Nets ◽  
Storage System ◽  
Cloud Service ◽  
Computing System ◽  
Cloud Services ◽  
Service Architecture ◽  
Distributed Computing Systems ◽  
Computing Systems ◽  
Replicated Databases

Purpose of research. The object of the study is a network cloud service built on the basis of a replicated database. Data in distributed computing systems are replicated in order to ensure the reliability of their storage, facilitate access to data as well as to improve the storage system performance. In this regard, the problem of analyzing the effectiveness of processing the queries to replicated databases in a network-based cloud environment, and, in particular, the problem of organizing priority query queues for updating databae copies (update requests) and for searching and reading information in databases (query-requests). The purpose of this work is to study and organize priority modes in a network distributed computing system with cloud service architecture.Methods. The study was conducted on the basis of two types of behavioural patterns: models based on Petri nets to describe and verify the functioning of a distributed computing system with replicated databases represented as a pool of resource units with several units, and models based on the GPSS simulation language for possible evaluation of passage of query time of each type in queues depending on the priority of queries.Results. Based on two simulation methods, the operation of a cloud system with database replicas was analyzed. In this system two distributed cloud computing systems interact: MANET Cloud based on a wireless network and Internet Cloud based on the Internet. These databases together are the basis of the DBaaSoD (Data Bases as a Service on Demand) cloud service (databases as a service organized at user’s query). To study this system the models of two classes were developed. The model based on Petri nets is designed to test the simulated distributed application for proper functioning. The decisions on the mapping of Petri nets on the architecture of computer networks are discussed. The simulation statistical model is used to compare the priority and non-priority maintenance modes of query- and update-requests by the criterion of average passage of time of queries in queues.Conclusion. System models based on Petri nets were tested, which showed their liveness and security, which makes it possible to move from models to building formalized specifications for network applications for network cloud services in distributed computing systems with replicated databases. The study of GPSS-model showed that in the case of priority service of update-requests, the time of passage for them is reduced by about 2 to 4 times compared with query-requests, depending on the intensity of the query-requests. In the non-priority mode, the serving conditions for update-queries deteriorate and the time of passage in the queue for them increases by about 2 to 6 times as compared with query-requests depending on the intensity of the query-requests.

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