The opportunity of application of the device of Petri nets to modeling decision-making process (DMP) and management by it is considered. DMP is based on question-answer (QA) structures received as a result of work with the shaper of the QA-structures "WIQA for Windows 95", developed on faculty "Computer Facilities" of Ulyanovsk State technical university.
The QA-structure reflects actually technique DMP and represents activity network (event network), as which tops units of activity (task, question, answer etc.) designer (group of the designers), registered in a real time scale during the decision of any problem. Therefore, DMP, actually, there is a question-answer process.
The QA-structure can conditionally be broken on two semantic parts: questions, describing the script of work and answers, containing the decisions. The modeling of question-answer process occurs under the beforehand prepared script (technique of designing). The script can be given by the designer (chief of design works) as a pattern for the future decision or the script of the ready decision received earlier can be used. Thus is used a question part of QA-structure and during modeling is formed answer-back.
During modeling is admitted to change the script, that makes DMP more flexible and does not put the designer in rigid dependence on a technique of reception of the reference decision. At the same time, on set of potential techniques it is possible to formulate a task of a choice with determined criterions, ensuring allocation optimal ways of the decision. The formulation of such task on representation of QA-structures as Petri nets is offered.
The provisional sketch of a technique of acceptance of the decision on the basis of the WIQA-script is those:
Choice of the script of modeling. It is possible to use or question a part of the ready WIQA-project, or to open the new project and to create a pattern of the script.
Choice of one of the following variants of continuation of work:
Transition in mode of operations with the contents particular, chosen from the offered list of front of works, unit of designing (reception of the local answer). Till end, in case of giving to work of the status «work is completed», start of transition appropriate to performance of work and transition to item 2.
Change of the formulation (contents) of one of works offered for a choice. Till end transition to item 3.
Change of structure of the script. In this case there can be some possible variants of continuation: 1) transitions in usual mode of operations with the termination of modeling; 2) transitions in a mode of editing a question part of the project, till end - nullification of a condition of modeling (i. e., dump of all parameters) and transition to item 2
Undo on a step back and transition to item 3 with the previous condition of the project.
Analysis of the received project. At this stage the representation of QA-structure as the PERT-graphics can be used.
In the multiuser version the chief of design works can break the script on groups according to the one whom from the designers this or that particular work will be charged to (i. e., to each element question of a part the author is attributed and in each step of modeling the list from those works is offered on the decision to the designer which to it were nominated by the chief).
Use of the device of Petri nets for modeling DMP allows essentially to raise its productivity and efficiency due to precise organization of work according to logic of the script, its flexibility, opportunity backspacing and passage of several variants of ways of reception of the decision.
P. I. Sosnin, D. S. Verbichenko MULTI-USER VERSION OF QUESTION-ANSWER PROCESSOR WIQA (WORKING IN QUESTIONS AND ANSWERS)
Question-Answer (QA) processor WIQA was developed in Computer Science Department of Ulyanovsk State Technical University. The main purpose of this system is interactive registration of CAD user activity during design process. The result of this registration is representation of designer experience in the form of question-answer structures (QA-structures). Further processing, analyzing and visualization of these structures provide means of sharing experience in designer’s workgroups during solving similar problems in future.
Till now WIQA was single user application, running on a local machine. Each designer had his personal database; process of sharing QA-structures with other designers was complex and inefficient. In spring 1999 was released first multi-user version of WIQA system. It run’s under Windows 9X and Windows NT platforms.
Multi-user version of WIQA system is based on client-sever technology and using TCP/IP as a transport protocol. WIQA server manages project database and provides extended administrative functions. Client part of WIQA system is a combination of full functional local version WIQA system and a client part that provides access to network services of WIQA server.
Fig.1 (Block structure of multi-user WIQA system) Large projects can have very complex structure consisting of big amount of QA-nodes. Each node can also have associated objects embedded with OLE 2 technology. This ability allows to embed into project any documents generated by user’s CAD system, and if it also OLE server functions user can in-place activate embedded documents from WIQA, using standard OLE mechanism. Each node can have associated dossier with non-limited number items in it. Each item also supports OLE embedding features. Dossier is used to hold information used during work on this part of the project. It can include help information, electronic books & articles (for example from Internet), illustrations, CAD files etc. Format of these items makes no difference because they are embedded as OLE documents or as ordinary files. (Note: OLE embedding feature is realized only in 4.0 version of WIQA)
Due to the problem of “traffic jam” because of the large amount of project information need to be sending over the network, specific attention was devoted to design optimal dataflow algorithms. The most critical and frequently used project information is cached on the local workstations during initial project opening and initializing procedures. All embedded objects and dossier item are loaded on demand when user wants to open them. Opened objects are also cached so reopening them don’t need to call request to server. In the current state of WIQA system the necessity of regenerating cached item is determined by version number of the node, which still requires many calls to server in case of big number of project nodes. Soon it is planned to organize the notification service that commands client workstations to regenerate their caches. It is also planned to incorporate some intellectual functions in client cache regenerating routines, for example: to load in order their be needed during execution of the current process, or load small nodes first to minimize waiting time.
A policy of multi-user interaction and conflict resolution provided by server guaranties data integrity and excludes it ambiguity. Each user has it personal login and set of rights depending on his role in project design process.
With the help of multi-user support WIQA systems has new expanded capabilities of organizing operative experience sharing process in a designers group and simplify task of centralizing QA-structures processing and storing. Project manager now can monitor progress of designing project in real-time and don’t need to collect data from all workstations. Now multi-user version of WIQA system is on the stage of beta testing.