Modeling of polygraphic web-service using colored Petri nets

Abstract

The use of Petri Networks as a tool for graphical and mathematical modeling of complex systems and processes has recently been widespread. Visual representation techniques and simulations, such as Petri colored networks, are effective at the development stage of complex systems, since they allow formally to describe and model the system at different levels of abstraction and investigate them dynamically. An example of a dynamic system is web-services. Web services and their components can interact with different applications that meet the standards of web services. As a rule, one service does not meet the needs of users, and services are becoming more and more complex. In fact, a modern web service is created by combining different web services and their components to create a component service that offers a set of new functional services. When combining and sharing Web services the most critical is the interaction of Web services and their components among themselves, which requires a detailed study of the functioning of the processes and modeling their behavior to improve their efficiency.
Polygraphic web-service is a complex program system that organizes the provision of printing services. It works with the client through the Internet and provides an opportunity to find the necessary service at the printing centers for the best possible means, to make an order, to use various services, to pay for services, to choose a means of payment and delivery of printed products. The complex structure of the web-service requires the study and modeling of the interaction of its components to ensure the effectiveness of the operation.
To model the composite web service system, it is necessary to identify the main and auxiliary subsystems by means of structural analysis. The block diagram of a web-service is presented in fig. 1. As a structural analysis tool, we used a data flow diagram (DFD) in the notation of a similar Heine-Sarson notation. A top-level contextual chart contains a set of subsystems connected by data streams.
A model of a polygraphic web-service in the form of Petri's network in a hierarchical form was developed and presented for the purpose of analysis of separate networks of the second level. This enables to analyze all parts of the network separately and use the results to formulate conclusions about the correctness of the construction of the entire network. In the presence of links between networks of the second level, it is necessary to add additional criteria for the analysis of networks, which are connected with the addition of the main network of cities and transitions between networks of the second level, the number of which depends on the number of possible states of interaction between networks of the second level.