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The goal of this chapter is to identify certain issues that you must address when building a robust application for your organization. The sample code demonstrates a way to implement a system of user IDs and passwords, and makes use of sessions.
Building and maintaining an application for real-world use is a substantial undertaking. The basis is the understanding of Web technologies and database technologies that you have gained from studying this text, implementing the examples, and working on the exercises. However, most applications will require attention to additional matters. In this section, we will provide a brief introduction to several issues that can be critical to the operation of applications.
The first sentence of this section contained hints of important, but frequently overlooked, aspects of application development. You must not only build an application, you need to maintain it. Furthermore, you are building the application for use in the real world. The context of operation is important. You need to pay attention to how this application relates to everything else going on in your own organization, and how it fits within the life of the users. This involves keeping track of the actual usage and making modifications as required. You might encounter problems of success: your site might have more business than you anticipated. This can cause changes in the storage space allotted on the server for the application. It also could mean that you need to focus on controlling concurrent access to the database by multiple users. You also must provide for problems such as electrical outages and attacks by hackers. Particular instances of such problems might be beyond your control, but it is your responsibility to build a system for detection and recovery. One unpleasant thing to consider is how to guard against mis-use of the information by insiders of your organization.
Facilities exist both in the database management systems (DBMSs) products and in more elaborate coding of PHP and ASP that support the building and maintaining of robust applications. Plug-ins are available for a fee, and open-source developers continue to provide new offerings. Web Services, described briefly in the next chapter, will emerge as an important category of tools. You need to consider and continually monitor the specific circumstances of your situation to determine what is required.