Chapter 6: Desktop Application Development

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Introduction

In Chapter 5, we discussed some very powerful object-oriented languages. This chapter will give us some in-depth insight into the different concepts of developing Enterprise-class applications, including graphical user interface (GUI) applications such as drag and drop, multiple document interface (MDI) style applications, and database and multi-threaded applications. Development of GUI applications for the traditional UNIX platform has long been merely a dream, due to the complex X-Windows architecture and the cost associated with the required hardware. However, the X-Windows-based development has gained momentum in the past decade and slightly beyond. Several groups have attempted to independently develop X-Windows-based API (Application Programming Interface) for different UNIX versions. Still, the fact that an API developed for one UNIX version might not run for another remained a problem. The evolution of the Linux operating system raised fears in the minds of industry specialists that Linux would add a new dimension to the already complex problems of graphics-based UNIX development tools. Contrary to this belief, Linux has brought a sort of discipline to the open source programmer community and has accelerated the process of developing GUI-based development tools. Undoubtedly, today’s Linux operating system poses tough competition for other GUI-based operating system such as Windows and Mac OS. As a result, the open source initiative (and many other commercial vendors) contributed to expanding the GUI-based development tools to other traditional UNIX operating systems. Examples of such tools include the Tcl/Tk (Tool Command Language & Tool Kit) package and Trolltech’s Qt (pronounced as “Cute”) API. Both these libraries are available on multiple operating systems such as Linux, Windows, and HP-UX, to name a few. There are several other APIs based on these libraries, built by open source groups as well as commercial vendors. In addition, the Java Developer Kit (JDK) and other associated APIs such as J2ME (Java 2 Mobile Edition) and J2EE (Java 2 Enterprise Edition) from Sun Microsystems form another set of popular cross-platform development tools useful for developing desktop and Enterprise class applications. This chapter focuses on the Linux Desktop development using the Borland Kylix tool for Delphi and C++ languages and Borland JBuilder8 tool for Java development. The Kylix tool is built upon the existing Qt library from TrollTech; JBuilder8 is one of the popular Java development IDEs. Other popular Java IDEs include Oracle JDeveloper and IBM WebSphere Application Developer. Although the initial part of the chapter is devoted to Kylix-based development, the Java IDE-based development is discussed in the latter part of the chapter.

The introduction of Kylix development platform has brought a revolution in the development of standalone Linux desktop applications in the native ELF executable code format combined with the RAD nature of Borland tools. Here the word standalone means that the applications built using Kylix platform are not dependent on other libraries. Kylix is shipped with compilers for two of the powerful object-oriented languages that it supports—Delphi and C++. Chapter 5 laid the groundwork for readers to quickly grasp the programming fundamentals required for using this tool. In this chapter, RAD-based development with the Kylix IDE will be discussed to a considerable extent, with the sole purpose of familiarizing developers with this tool. Kylix is available in different editions, including commercial and open editions. Although the commercial editions are available for a price, the open edition seems to be available through the GNU General Public License, based on the information available on their Web site, www.borland.com. As mentioned in Chapter 5, Kylix is equipped with the CLX component library. Also, the Enterprise edition contains the CLX library in full, and the other two—professional and open editions—contain a subset of the components. Borland Corporation should be contacted for more details on these product editions, their prices, and so on.

When using the Kylix IDE, the developers do not have to invoke the command-line compiler (such as dcc or bc++) for compilation. The IDE performs the compilation and all the associated tasks as requested by the programmer by setting compile options visually, and selecting associated menu items from the IDE. The current release of the product is Kylix 3, which is discussed in this book.

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