INTERNATIONAL DESIGN CONFERENCE - DESIGN 2000 Dubrovnik, May 23 - 26, 2000
THE IMPLEMENTATION OF WEB-BASED
TECHNOLOGIES IN ENGINEERING DATA
MANAGEMENT
Pavlić Davor, Dorian Marjanović, Štorga Mario Keywords: EDP/PDM, WWW
Abstract: There are various data archive related problems occurring in medium-size companies. Larger companies have been preventing such situations by implementing different EDP/PDM systems. Smaller companies find such commercial EDP/PDM systems too expensive when compared to the number of employed users, that enable them to handle the archive manually. Due to its rather general setting, various EDP/PDM systems often cannot meet all the specific requirements of the small user. SME archives relies on a larger number of users who commonly encounter operational problems. Such is the case with companies that have no strictly defined archive principles or browsing systems. On the sample of a medium size company of power transformers, we have studied the parameters necessary for the design of a software that would implement web based technologies in order to enable simpler and more precise the bill of material be created. The advantage of applying web technologies in data management is that the user needs no other software application besides the web browser as already installed in his computer. In addition to that, the user is not limited by his choice of operating system (Windows, Unix).
1. Introduction
Striving to improve and optimze the production process, companies have been increasingly computerizing certain areas of business management. One of the leading producers of power transformers facilities has introduced basic 2D CAD system in the Design Department to meet the time reduction requirements. Although, designer engineers have been using well-known drafting systems, the goal was not reached. The problem was identified in the organizational aspects of the design process. One of the proposed solution was based on market omnipresent general-purpose EDM/PDM systems. However, the high prices and incapability to meet various specific needs of the users, have all together speeded up the decision making on developing a specialized system that would better fulfill the requirements. This article is presenting the authors’ approach to the problem and applied solution. In the second chapter a present situation is described. After that, certain outlines are given to help one chooses the principle solution in dealing with the path of reaching the final one. The production process of a power transformers could be described as a low volume production of valuable products composed of in function highly standardized assemblies. The range of products has been standardized by variations in structure form and performance. The standardized bill of material as a part of a layout drawing is top-level document of the product available to the purchase and maintaince.
2. The existing design process
The first stage of a project was a study of existing procedure in the design office. The study was conducted by interviews. The method we have used was based on the interviews with the members of a design department. The study was limited to the mechanical engineering design department. The power transformer was build from the following assemblies: Core, Tank , Windings, Main insulation, Leads, Tank cover and Conservator.
On the basis of the interview the picture of a existing design process a merge and relations among the personnel: Head of Design Department, Senior Designers and Designers, their duties and the workflow became apparent (Figure 1).
Head of the Design Department
Senior Designer
Designer
Senior Designer
Designer
Figure 1. Personnel of Design Department
Head of Design Department is in charge of starting new projects according to the data received from the Project Department officers. The new project is then assigned to one of the Senior Designers. The problem noted at this stage, was that there are lake information available on workload of each of the Senior Designer due to the lack of one comprehensive source of such information gained there. The Senior Designer is responsible for the products’ conceptual design. A serious lack of information available is evident: it is difficult to gain sufficient information for basic conceptual design. We assume the information gap is a result of nonexistent device for comprehensive database of ready-made solutions that could be applied in new conceptual design projects. With the conceptual design being done, the Head of Design Department assignees other designers with specialized tasks of developing particular assembiles. We face the problem of insufficient or nonexistent information on both parameters required for the project be completed and staff members’ workload.
2.1 Identified problems
Base on the data gathered in the interviews we have been able to identified several problems within ME design department. We have grouped problems in organizational and technical category. The organizational problems were:
• Lack of the standardized design process and instructions
• Lack of the standardized projects’ data, archiving and retrieving
The technical problems were:
• The bill of material was created fully manual
• Lack of methodically categorized e-documentation
Within a group, all individual items were numbered manually, without stored records on actually applied numbers, leading to the holes in numbering system. The records on already designed parts were not categorized so the information cannot be retrieved for further use. Such a situation causes that already available elements are left idle. The above mentioned problems emphasized two steps in Design Department re-engineering. The first one provided support in information management within Design Department, which we have defined as the major issue and object of the research in this article. The second step is the implementation of a fully 3D modeling system integrated with the informational management system. At the present state the both systems have passed the initial tests for the subset of the products’ domain.
3. Handling Data in the Engineering management
The major objection to the situation found is lack of the systematic management scheme applied to the data manipulation at he department level. Most of documents are created in various computer applications, thus being quite manageable. The documents are only used, but there is no mention of system control, security measures or backup.
There are four main activities to be defined while developing a software system:
• A step by step defining procedure for the particular group of users
• Creating database required for specific data management
• Choosing a development environment, developing required procedures and defining the user’s interface
• Implementing the security systems
We have already described the defining process for the particular user group and will therefore avoid reverting to this subject in more details. Applying a number of related databases could do data storing in Engineering Management: the database of particular power transformers, template database, common database and database of standard parts. Such a comprehensive approach would enable faster data handling and browsing, smaller size database and the option of individual backup per each of the power transformers.
3.1 Common database
The common database contains information on projects, users, task division, browsing parameters and standard parts. All the mentioned elements are collected within the database, since they are all together necessary for project completion in Design Department. The data rarely change but can be easily updated. Information on standard parts can be saved in a separate database, yet being generally the same for all projects; it is not necessary to extract them in particular. The project data cover information on ID number and project title, Senior Designer and current status of the pending project. The project can be saved in the archive or active, but also showing information on conceptual design. The information on standard parts is divided into a couple of mutually related tables. The standard parts itself are grouped by assemblies. It is necessary to consider the possibility of one standard part being represented in a number of assemblies. The ”∞ to ∞” relation established between the two tables treats this problem. Each of the standard parts may have a couple of versions, which makes the ”∞ to
∞” relation a prerequisite between the tables as well. The data presented in the Standard Parts tables contain the ID number, name of the standard part and title of the document saved in PDF format, most advisable. Such a format is extremely useful for mixed documents, i.e. containing text and graphics. The problem of numbering by default is the already mentioned one of nonavailable records on the last used digit, but writing down the last applied number into a special table can solve this.
3.2 Template base of power transformers and individual database
Information on hierarchy of the parts referring to the standard models of assemblies is contained in the template database. This enables us to choose among the standardized assemblies in conceptual
designing process. The data on it are copied from the template base into the active project one. The structure of a particular base must be identical to the template base structure, since they are mutually copied. The template structure is founded on data about assemblies and parts. The assemblies (A) stands of the parts (P)/sub-assemblies (A), including an element with subordinate elements (children’s) whereas the part (P) refers to the one and inseparable element. The scheme of the template base structure is explained as a network structure presented on the figure 2.
A1
A2
A3
A4
A
A5
A2
P1
P2
P3
A6
P3
P4
A
Figure 2. Template base network structure
In such a network structure, it is possible that one assembly (A2) is present in a number of assemblies, just as a assemblie can contain of a few assemblies. The structure is reached by applying the ”∞ to ∞” relation between assemblies and assemblies and assemblies and parts. The ”∞ to ∞” relation used between assemblies and assemblies, and assemblies and parts presumes that the assemblies may have a subordinate group of assemblies/parts (children’s) but it is also possible for one assembly (A4) or part (P1) to operate with a number of superordined assemblies (parents).
4. Choosing the Web architectures
Due to multiple users and dislocated design departments, 2-tier client-server model seems to be the most natural choice [Williams, Evans]. The client-server architecture consists of one or more client applications communicating requests to another application, which is designated as the server. The client-server model comes in various flavors, but the concept (working principle) is always the same:
1. The client initiates a request to the server, which is waiting for requests being stand-by 2. When the server receives the request, it manages and carries it out. Then it sends a
response message back to the requesting client.
3. The response may come as a group of records, an error message or a Boolean value indicating whether the statement has been executed successfully.
Another variation of the client-server model is a thin client–fat server and a fat client–thin server. In the fat client–thin server model, most of the functionality and business logic resides on the client, which creates more network traffic. A thin client–fat server implies that both functionality and business logic mostly reside on the server. Business logic consists of a rule that describes the way data
should be handled. A great deal of this business logic is probably handled by the stored procedures. The advantages and disadvantages of fat client and fat server models are presented in the tables 1. and 2.
Table 1. Advantages of fat client and fat server models
Fat client – thin server Fat server – thin client
Architecture is simple to design and build Upgrade multiple machines with little effort Relieves server from handling business logic Allows for smaller executables on the client
Table 2. Disadvantages of fat client and fat server models
Fat client – thin server Fat server – thin client
Increased network traffic Requires the server to do more processing May require a more powerful machine Requires a Database Administrator to build and
maintain the business logic Difficult and time-consuming in upgrade for
multiple clients Complex development environment
The ultimate expression of a thin client–fat server model is the World Wide Web. Browsers have generic information on how to handle each response to a request, so when a new request is received, the server processes it according to its stored logic.Architecture implemented in project and presented in this article involves 2-tier thin client–fat server architecture. The 2-tier architectures consist of one or more client browsers directly connected to the server. Such a design is presented on the figure 3.
DATA STORED PROCEDURES TRIGGERS BUSSINES LOGIC FILE SERVER HTML DOCUMENTS ASP DOCUMENTS ACTIVE X COMPONENTS VB SCRIPTS JAVA SCRIPTS EMAIL DATABASE SERVER WEB SERVER THIN CLIENT WEB BROWSER EMAIL CLIENT
SERVER
THIN CLIENT WEB BROWSER EMAIL CLIENT Re quest Resu lts Requ est Re sultsFigure 3. Application - Web Architecture
On the figure 3 the following server's components are depicted:
• Database server
• Web server
• File server
Database server is a relation database that contains data, software business logic and procedures. The function of an Web server is presenting HTML and ASP documents. An ASP page is HTML page that
includes server-side script. After the server-side script on an ASP page runs, the result are returned to the client browser in the form of a standard HTML document. The server-side scripts are VB scripts or Java scripts. Also, an ASP page can call ActiveX components to perform tasks.
5. Conclusion
This paper is a result of a comprehensive research in project development time reduction in Design Department. The problems faced within the Department have been stressed here and the necessity of introducing the computers help handling the backup process. This goal can be achieved by saving the data in the archive using a number of related databases, the operation environment being WWW. The main advantage of the WWW technology is that it enables the user to rely on just the Web browser, without limiting his choice of operating system. After we have analyzed both advantages and disadvantages of different client-server architectures, we chose the 2-tier thin client–fat server architecture. Future problem related studies should focus on implementation of the particular user’s operations through software procedures defining of the user’s interface and security systems.
References
Rieg, F.,”The Paperless Technical Department”, Proceedings of the International Conference on Engineering Design,Munich 1999
Williams, C. “Professional Visual Basic 6 Databases”, 1999
Evans, N. & Miller, K. & Spencer, K. “Programming Microsoft Visual InterDev 6.0”, 1999
Davor Pavlić, B.Sc.
University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture Design Department
10000 ZAGREB, CROATIA Phone. +385 1 61 68 369 E-mail: davor.pavlic@fsb.hr
