Chapter 1. An Introduction to APEX

Oracle Application Express APEX for short, or by its former name HTML DB is a declarative, Web-based RAD (Rapid Application development) tool. It is used to develop native Web-based, data centric applications.

Let's clarify some of these terms, and understand what they mean in the APEX context.

Web-based

The term Web-based appears in the description of both the development tool and its product the APEX application. We are using a Web browser to both develop and run our applications. The advantages are obvious. Web browsers are installed, almost by default, on most of the workstations we are using, independently of the workstation hardware or operating system. It means that on the client side, we don't need anything else to start developing with APEX, or to run APEX applications. Moreover, it means very easy access to our applications, both internally using Intranet or externally, using the Internet. If we add all the modern smart phones and other PDAs on the market today, which include built-in Web browsers, we'll come to the conclusion that the range of options to access our APEX applications is very wide.

Another important advantage when using a Web browser is the ability to free us from hardware and local operating system dependencies. As the APEX Application Builder actually generates HTML code, we (as developers) don't have to worry about the hardware specifications, or the local operating system our end users will be using, to run our APEX application. As long as they have access to an HTML supporting Web browser, we are covered.

However, Web based application development can also be a drawback. Unfortunately, not all Web browser manufacturers have fully adopted all the international standards in this field. As a result, there are cases in which different Web browsers will display the same code page differently. The variety of Web browsers in the market today, like Internet Explorer, Firefox, Chrome, Opera and Safari, just to name a few, support and implement HTML, XHTML, CSS and JavaScript versions and levels, in different ways and styles. There are known cases where even the same Web browser brand, but in different versions, or across local operating systems, delivers different results with the same code. We need to be aware of this, and take actions to resolve it if we want to ensure cross-browser compatibility code for our applications (which will apply to greater numbers of potential users). Sometimes we need to take hard decisions and waive the support of certain web browsers in order to keep our code simple and maintainable.

A list of supported Web browsers can be found in the APEX release notes. For version 3.2, which is the latest APEX version at the time of writing this book, it can be found at http://download.oracle.com/docs/cd/E14373_01/relnotes.32/e13365/toc.htm#BGBCEGBI