A framework for web-based product data management using J2EE

Transcription

1 Int J Adv Manuf Technol (2004) 24: DOI /s ORIGINAL ARTICLE M.Y. Huang Y.J. Lin Hu Xu A framework for web-based product data management using J2EE Received: 8 October 2002 / Accepted: 13 March 2003 / Published online: 27 October 2004 Springer-Verlag London Limited 2004 Abstract Because emanufacturing is motivated by the emerging need for distant collaborative design required among R&D centres and manufacturers of global-based enterprises, web-based product data management becomes an essential tool for realising the technology. In this paper, the design of a web-based product data management (WPDM) system is presented. The developed WPDM is aimed at achieving the goal of emanufacturing by providing an effective tool for product database management through the Internet utilising JAVA and J2EE technologies. In our scenarios, all the involved engineering and management team members who need WPDM are inherently located dispersedly. The ultimate goal is to optimise product cycle time and upgrade a traditional PDM system to face the challenge of the new era of global business competition. Basically, the proposed WPDM is developed in such a way that it allows designers/users to create, view and manipulate product data through the World Wide Web, while founding the architecture of the web application on a three-tier client/server system. The current WPDM of our design mainly uses servlets and JSP to handle user inputs and manage and retrieve product data from the database through the JDBC driver, with the server components stored on a middleware program called Tomcat. Within this environment, all parties involved in product design and manufacture can access the WPDM log-in page with the given URL after a successful identity authorisation. Consequently, these users can create, search and/or manipulate the desired engineering data through the enabled WPDM. The WPDM developed in this work has been experimentally tested in the lab. Keywords emanufacturing J2EE PDM Web-based product data management M.Y. Huang ( ) Y.J. Lin H. Xu Department of Mechanical Engineering, The University of Akron, Akron, OH , USA ylin@uakron.edu Tel.: Fax: Introduction Product data management (PDM) is the essential technology of concurrent engineering. It manages and controls engineering information and can function as a tool to integrate many different product-related pieces of information. A PDM system is a software framework which provides the mechanism to capture and enforce a specific product development process consistently according to how an organization does business. In today s business world, when global business mandates that design and manufacturing facilities be dispersedly located, the traditional PDM system is insufficient and has the following potential shortfalls: 1. It cannot provide access to users at different locations, especially those on different networks. In each implementation of the PDM, the network configurations must be homogeneous. Hence, a bottleneck emerges for global companies wishing to implement PDM. 2. The PDM client applications are platform dependent, which means either all users must use the same computer platform or a specific application must be provided for each user platform. In the new business model, it is nearly impossible to mandate that all the potential users choose the same platform or the same operation system. 3. The current PDM system is not easy to extend. Whenever new features are demanded, users must re-install or upgrade the client application completely. Therefore, it increases the maintenance cost when a company is becoming globally based. In view of the deficiencies of the traditional PDM systems, we should take advantage of the rapidly improving Internet technology and incorporate it into current PDM systems to meet our needs. The advantages of integrating the Internet into PDM systems are obvious, namely: 1. The Internet provides a mechanism for worldwide electronic information sharing and reshapes PDM systems. Thus, it can offer business-centred solutions and provide global communication effortlessly.

2 There are many similarities between web-based technologies and PDM methodology as PDM systems move toward a three-tiered distributed architecture. This makes using webbased technologies in PDM systems a logical move. 3. Building PDM-based systems on web technologies could easily provide platform-independent features, which would avoid the overhead cost for implementing PDM in different networks on various computing platforms. In this paper, product data management is reviewed first. Then J2EE technology is introduced, followed by the elaboration of the proposed web-based product data management (WPDM). WPDM is a web application aimed at developing a web-based collaborative PDM environment, using the Internet as the application infrastructure to allow the involvement of multiple parties in geographically dispersed locations during a product s life cycle. The possibilities of building WPDM on J2EE technology is discussed, and an example implementation is introduced to illustrate the work flow. By comparing it with traditional PDM, it is anticipated that building web-based PDM systems based on cross-platform Java and J2EE technologies will bring fresh ideas to this field. Finally, a conclusion is drawn and future research discussed. 2 PDM technology Product data management (PDM) plays an important role in tracking products among different engineering groups. When successfully implemented, it can reduce time to market, increase product quality and reduce total cost. PDM controls, manages and can distribute product data automatically to the people who need them. A PDM system is typically used within an enterprise to organise, access and control data related to its products and to manage the life cycles of those products [1]. 2.1 PDM functionality requirement It is not easy to choose a good PDM system which satisfies the timing needs of a company and offer the flexibility to grow as the company grows. The functionality a company requires depends on many things. For example, the type of product, its organisation, the systems which are in use, the skills of the people who will support the PDM system, and the progress that has been made toward an effective engineering environment [2]. PDM users include those people working in such applications as CAD/CAM and people working directly in a PDM environment. A user can send requests to the PDM system by computer; the PDM server then handles the requested tasks, using the metadatabase search engine to search through the managed files, and sends the response back to the user. Figure 1 shows a functional view of a PDM system. To implement a good PDM system, some basic functionality requirements must be met [2]: A PDM system must be fully scalable to provide flexibility because every organisation has different priorities and a different implementation. Fig. 1. Functional view of a PDM system [2] The system must be easy to use. This requirement is fundamental to all software and is no less relevant in the context of PDM than it is to, for example, CAD/CAM software. The system must have an open architecture. This allows users to integrate it with the tools they currently use for design, engineering and manufacturing and to avoid a repurchase of expensive technologies, time-consuming transfer of data, training, etc., which are inherent disadvantages of switching technology suppliers. The system must be available on a wide variety of platforms and functions across heterogeneous networks to assure a common, concurrent engineering environment. The system must be rule-based and event-driven. This implies that users create the rules controlling how the system functions. They are not forced to adhere to the constraints imposed by the software. To ensure that these requirements are met, the specific PDM should include the following user functions [2]: Design release management: Provides security and access control, establishment of data relationships, check-in and check-out, global release definitions, user lists and meta-data management. Change management: Specifies process definitions, in other words, who approves what, and when. Product structure management: Provides part list and bill of material functions, part definitions, part relationship attributes, and the ability to associate product defining art with parts and structures. Classification: Provides tools to search for and retrieve standard parts and existing design data. Program management: Creates work breakdown structures and schedules resources. Furthermore, a PDM system should also provide some utility functions such as data transport, data translation, image service, system administration and data communication. PDM brings many benefits when successfully implemented, which can be summarised as follows (courtesy of Hewlett- Packard, Understanding Product Data Management ): Reduced time to market, Improved design productivity, Improved design and manufacturing accuracy,

3 849 Better use of creative team skills, Comfortable use, Safeguarded data integrity, Better control over projects, Better management of engineering changes, Major step toward total quality management. 2.2 Why web-based PDM? With the maturing of web technologies, the Internet plays an important role in developing PDM systems; web-based PDM can be seen as a natural extension. The Internet provides worldwide data sharing, and web browsers provide a simple interface that is inexpensive, easy to use and capable of supporting all users. Traditional PDM systems are usually built on local area networks (LANs); thus the user must be on a specific network to access the PDM services, but in today s business model, PDM users tend to be located in remote locations. In traditional PDM systems, C/C++ is the major building language, which is dependent on the hardware platform, so a client program must be installed for each user platform. This means whenever a new platform is added, there must be a new version of the client application, thus increasing the maintenance and upgrade cost. Web-based PDM will allow any users with Internet access to use the PDM services if users are granted permission, and for web applications, web browsers are used as the client application; PDM users need not install specific programmes to access the PDM system, so developers can avoid the overhead of upgrading client programmes for each platform. In addition, web technology is quite similar to PDM technology in both architecture and conceptual module. Figure 2 shows a comparison of web and PDM logical architecture. In some sense, PDM will be more adaptive if run on the web infrastructure. PDM and the web will enhance each other s capabilities and performance [3]. Therefore, web technology is an enabling tool for solving the problems and challenges faced by traditional PDM systems; it can provide platform independence, easy access of users and global communication among engineering team members located dispersedly; it can also improve the PDM s capabilities and performance. 3 J2EE technology J2EE is a Java 2 Platform, Enterprise Edition, developed by Sun Microsystems. It defines the standard for developing multitier enterprise applications and simplifies enterprise applications by basing them on standardised, modular components, by providing a complete set of services to those components, and by handling many details of application behaviour automatically, without complex programming. J2EE not only has many features in common with Java 2 Platform, Standard Edition, such as Write Once, Run Anywhere portability, JDBC API for database access, CORBA technology for interaction with existing enterprise resources, and a security model that protects data even in Internet applications, but also adds full support for Enterprise JavaBeans components, Java Servlets API, JavaServer Pages and XML technology [4]. The J2EE application model is a multi-tier model which goes beyond the limitation of a classical two-tier client-server application model. In the two-tier, client-server application model, installation and maintenance of business logic on every user machine cause administrative problems and delivering enterprise information systems (EIS) services to every user is a complex task. However, in a multi-tier application model, a middleware program communicates between the first-tier client and EIS, thus shielding the first-tier client from the complexity involved in dealing with the EIS tier. Figure 3 shows the major components of the J2EE architecture. Fig. 2. Comparison of web and PDM logical architecture [3] Fig. 3. J2EE architecture

4 850 From Fig. 3 we see that the middle layer is a J2EE server, which includes the EJB container and web container. The EJB container is the run-time environment which controls the enterprise beans and provides them with important system-level services. The web container is the run-time environment for JSP files and servlets. 4 Web-based product data management (WPDM) experiment Because of the advantage of the three-tier application model of J2EE, web-based product data management (WPDM) is built on it. The current WPDM mainly uses servlets, and uses JSP to handle user input, manage and retrieve data from the database through the JDBC driver; in addition, the server components are stored on a middleware programme Tomcat. Users can access the WPDM login page with the given URL and then build or search the engineering data after successful identity authorisation. The schematics of the entire architecture of the WPDM is illustrated in Fig Three-layer design of WPDM Since WPDM uses a three-tier application model, there are some basic designs in each layer for exploring the possibilities of building WPDM on J2EE technology Back-end database The back-end database management system (DBMS) of a PDM system is used to store and manage product attribute data and documentary information, as well as the relationships between data. It is like a data vault of the whole system. The DBMS is usually a relational database system which provides complete functionalities to manage the product. Since WPDM is built on Java technologies, any database could be used as long as the DBMS provided Java database connectivity (JDBC), which allows Java server programmes to access the relational database through a standard library. In our research, IBM DB2 is chosen for storing product data. A typical engineering database should contain information that allows users to browser or search the database to understand very easily the relationship between parts and products, such as product bill of material, part ID, part name, part drawings, etc. Since WPDM is aimed at implementing web technology on a PDM domain, a small but typical database is designed to meet this objective. For example, one table stores a list of parts with relevant attributes such as part ID numbers and part name which can reflect the major engineering information of the product Middle layer of WPDM The middle layer works as a control centre between back-end database and front-end user. When a user requests information, the middle layer will communicate with the back-end database, get the needed information, and then send it back to the front-end user. The middle layer shields the user from dealing with backoffice systems and databases, thereby increasing the flexibility and security of the web application. The WPDM user will use a web browser to access the WPDM at a specified URL; the user may send a request such as find a part with part name, to the server. The request is sent to the web server through HTTP; the web server will pass the request to the WPDM components, which could be as complex as EJB or as simple as a servlet/jsp; the server components are designed to handle the HTTP request from the client. Figure 5 shows in detail how the WPDM middle layer server components handle user requests: In this figure, the components are servlets and JSP located on a Tomcat application server. Tomcat is the official reference implementation of the Servlet 2.2 and JSP 1.1 specifications. It can be used as a small stand-alone server for testing servlets and JSP pages, or it can be integrated into the Apache Web server [5]. The application server works as a run-time environment for the servlets and JSP. The servlets or JSP will talk to the database server through JDBC, perform the transaction and send the response to the client in HTML format. WPDM could be designed with greater flexibility and more security with the powerful J2EE packages. Based on the J2EE ar- Fig. 4. Schematic of entire architecture of WPDM Fig. 5. WPDM architecture

5 851 chitecture, the ideal design is to use EJBs to communicate with DBMS through JDBC, using servlets and JSP to control how to present the result to the end user. In this way, the business logic for implementing PDM and method of representing the result to users could be separated from each other, providing the flexibility for users to customise the PDM based on their own product s characteristics Front-end design Front-end clients usually just use a web browser to access WPDM but do not limit themselves to the web browser. The J2EE architecture provides very extensive features, and web applications based on it could provide accessibility to any client meeting the specification, such as a Java application designed for a hand-held device. Major users will access WPDM through web browsers, so the user interfaces are mainly HTML pages and forms. Java applets and Javascript could all be used to provide an appealing graphical user interface on the web. Fig. 7. Screen shot of CREATE page of WPDM 4.2 Overview of WPDM functionalities To implement collaborative data management, the server-side functionalities are created to manage the concurrent access of multiple users. Figure 6 illustrates a basic overview of WPDM functionalities. Here we assume there are two engineers working on the WPDM, and several servlets are designed to handle the various user requests: 1. User successfully logs in on WPDM. 2. When the user creates a new part with relevant engineering information, the Create servlet is called to add the information to the database. Figure 7 shows a screen shot of a CREATE page. 3. If the user needs to find an existing part s information, the Find servlet will be triggered. 4. If the user wants to edit the existing part information, then the Edit servlet is called. 5. The user can find the engineering change information using the Echange servlet. Other functionalities included or to be included in WPDM are listed as follows: 6. From the Edit page, the user can view the CAD drawing through the link with the part name if this part has a drawing file. Figure 8 shows a screen shot of this page. 7. When the data of an existing part are being edited by one user, the record will be locked so it is read-only for other users. If other users try to access the data for editing before Fig. 6. Basic overview of WPDM functionalities Fig. 8. Screen shot of CAD drawing page of WPDM

6 852 the previous user checks it in, the server will reject the job request. 8. If one user changes the product data while the other users are accessing it, the server should send a message to them to notify them of the update information. 9. The server should keep track of all user transactions. 5 Conclusion and future research In this E-era the World Wide Web is growing rapidly, which changes the way we develop our products. The changes offer new opportunities in the product data management software business in that it is possible to implement web-based product data management with moderate performance. The proposed web-based product data management (WPDM) application presented in this paper was developed using Java and J2EE to take advantage of the newly emerging web technology. WPDM is based on a J2EE three-tier web application model to provide security and flexibility and allows designers/users to create, view and manipulate product data through World Wide Web. In addition, WPDM is developed solely with Java, so that it is independent of the operating system and computer platform. In the future, WPDM will be extended to integrate with other applications such as CAD and ERP to provide a complete web-based enterprise concurrent engineering environment. References 1. CIMdata (1993) PDM Buyer s Guide, CIM data, Ann Arbor, MI 2. Gascoigne B (1995) PDM: the essential technology for concurrent engineering. World Class Des Manuf 2(1): Chu S, Fan Y (1999) Product data management based on web technology. Integr Manuf Sys 10:

7