Designing and Developing Web-Based DSS
A decision-oriented diagnosis approach is important for Web-Based and Inter-organizational DSS. Simply making an existing DSS accessible using a Web browser or accessible to customers or other external stakeholders will often lead to unsatisfactory results. Once diagnosis is complete, a feasibility analysis is definitely needed for an enterprise-wide and any other potentially large-scale DSS. A systematic development approach must be explicitly chosen and managers must be involved in the development process.
Developing the user interface, models and data store for Web-Based DSS remain major tasks. A user interface remains important in a Web development environment and it probably becomes more important because so many users of various levels of sophistication can potentially access some or all DSS capabilities. The representations available to user interface designers of Web-Based DSS are comparable to those for standalone DSS, but the available operations expand enormously with the additions of hyperlinks and the availability of external data and document sources. Control and memory aids also change somewhat in a Web development environment.
The actual architecture implemented is usually simple. Most Web-Based DSS are built using a three or four-tier architecture. A person using a Web browser sends a request using the hypertext transfer protocol (HTTP) to a Web server. The Web server processes the request using a program or script. The script may implement or link to a model, process a database request, or format a document. The results are returned to the userís Web browser for display (see Figure 11.1). Web applications are designed to allow any authorized user, with a WWW browser and an Internet connection, to interact with them. The application code usually sits on a remote server and the user interface is presented at the clientís WWW browser.
Figure 11.1 Web-Based DSS architecture
Extensible Markup Language (XML) is a general syntax for describing hierarchical data. It is applicable to a wide range of DSS applications, including applications with databases, web documents, and searching. It is similar to HTML; however, in XML you can create your own tags to show a documentís structure. For example, in a document consisting of employee information, we could have tags like <name> </name>, <position> </position>, and <streetaddress> </streetaddress>. In HTML, we could only separate the information with <br> or <p></p> tags. XML allows Decision Support Systems to process documents, data, and information faster and more efficiently.
Common Gateway Interface (CGI) applications are server-executed programs used to dynamically create HTML documents. Many World Wide Web sites use CGI applications for dynamic web page creation, for taking values from Web forms, and for providing a Web-based interface to other applications, such as databases. CGI programs provide the back-end processing for many Web-Based Decision Aids and DSS.
Java is a general-purpose programming language. In "The Java Language: A White Paper," (Sun, The Java Language: An Overview, 1996) Sun describes Java as "A simple, object-oriented, distributed, interpreted, robust, secure, architecture neutral, portable, high-performance, multithreaded, and dynamic language." It is related to C and C++ but some capabilities are omitted and a few ideas from other languages are included. Java is a high-level programming language. Compiled Java code is architecture-neutral, so Java applications are ideal for diverse operating system environments like the Internet. The Java language provides a powerful addition to the DSS development tools for programmers. The official Java web site ishttp://java.sun.com/. The largest directory of Java applets and Java-related web sites is http://www.gamelan.com/.
Many desktop productivity tools like Microsoft Access, Excel and PowerPoint have the capability to create Web documents. These HTML generator tools can let managers and analysts share decision support materials prepared on their personal PCs with others in their company. In general, managers need to become more involved in the development of Web sites and DSS applications on Intranets and Extranets.
A number of specialized tools can help implement Web-Based DSS including Microsoft Front Page, Cold Fusion from Allaire (www.allaire.com) and Web DSS development software like dbProbe (internetivity.com). These tools can assist some experienced developers, but they can actually result in poorly developed DSS when used by people inexperienced in building DSS. End-users will build Web-Based DSS using Front Page or even Cold Fusion, but these DSS will probably have more detractors than advocates.
When a company embarks on building Web-Based DSS some problems can be anticipated and minimized. First, Web-Based DSS applications will probably encounter some peak load problems. During the business day many managers will want to access the Corporate Intranet and so a "high performance" hardware architecture that can expand to serve a large number of concurrent users is needed. This load problem is associated with the "scalability" of the hardware and software and the planning of the developers.
Second, the Web is a "stateless" environment that does not automatically keep track of configuration settings, transaction information or any other data for the next page request. To avoid requiring users to re-enter information such as user name and password, Web-Based DSS applications must keep state information from one Web page to another. This creates new security issues for companies wishing to make sensitive internal data accessible to users. User authorization and authentication are challenging in the Web environment because of the large number of potential users.
Third, we are all having trouble keeping up with changing Web technologies. We need to learn rapidly in this environment. Both managers and technical staff need to learn about Web technologies and then be prepared to keep up with new developments as they occur. Despite these problems or challenges the Web is and should be the platform of choice for new Decision Support Systems.