This chapter explained some of the basics that will be presented in future chapters. It essentially explained that software engineering using the Commons is a task-driven approach, not a pure object-oriented approach. Using tasks is similar to using patterns, except that the tasks are defined in more generic terms.
The Commons includes a number of components that have proven their worth in other projects. That is the point of the Commons. In the charter of the Commons, it is a requirement that the component already be popular before it is accepted. In fact, before being even accepted into the Sandbox, the component must have some type of following.
Many people say that the advantage of Open Source is that you have the sources and can modify them to suit your needs. Some people say that this is a disadvantage and makes for second-rate or unprofessional software. The truth of the matter is that Open Source has nothing to do with quality. There is bad Open Source software and good Open Source software, just as there is good and bad Closed Source software. You can distinguish Open Source and Closed Source by thinking of it like this: imagine you are checking the oil in your car. With Open Source, you can check and add your own oil. You could even change your own oil. It is your choice. With Closed Source, you don t have these options; a specialized technician needs to handle every change and update.
When you are in the process of selecting which Open Source to use, of course you need to look at its quality. As a consumer of components, you will probably not select a package that does not compile out of the box. If a couple of tweaks related to jar locations are required, then that is acceptable, but it s unacceptable if the Open Source requires manual source code or build file updates.
If you are willing to invest the time to update the component, that is acceptable. However, if you can t update the Open Source component within five minutes, it most likely will not compile out of the box. If you must update it, that may take between a day and a week, assuming that you are very knowledgeable in the field.
One problem that the Commons could run into is that it could be overrun by thousands of potential frameworks that solve all of the problems of the software world. Therefore, the requirement that the component has to already be popular and used ensures that only the most useful and versatile of components will enter the Commons. Maybe this policy discriminates against new components, but the Commons wants to ensure that only the best of breed survive. This only enhances the value of the components in the Commons for end users.
On the CD The CD-ROM contains all of the sources accompanying this book. If a complete Java 1.4.x SDK and Java J2EE SDK environment is installed, the remaining needed tools are provided by the accompanying CD-ROM. At the end of each chapter the location of the appropriate sources that demonstrate the concepts shown in the chapter are given. At the URL http://www.devspace.com/content/ jseng .htm the latest changes and updates to the sources can be found.