As a developer one likes to have applications that can be distributed in easy, installable setups. Since the installation setup is the first
interaction of the user with your application, you would like to have all installation tasks be done like a breeze. Nullsoft has come out with a script-based
program, NSIS, that helps you create such an installer (i.e. setup.exe).

Nullsoft Scriptable Install System (NSIS) is an Open Source package that allows programmers to make Windows-based installers for their applications. NSIS has two components-script and a compiler. In order to create an installer for your software, you need to write a script which will decide as to how the installer will behave. For example, the path for installing the software and what all registry changes it needs to have.

Plus, the shortcuts it will create on the desktop.

Once you have written the installer script, you need to compile it in the given compiler, which will give you the final distribution as a 'setup.exe' file. Installer created with NSIS is compatible with all versions of Windows (be it 95 or Vista).

Getting started
We have given the NSIS package installer on this month's PCQ Professional CD. Copy the NSIS package installer on your Windows machine first. After installing the NSIS package, you need to create a script. For this open a Note pad and start writing the installation script for your software. Let's see how a script to build an installer for a JAVA program works.

It makes an installer setup for a simple Java program that does the following tasks:

• Copies all class files into the installer package.
• Creates Start Menu icons for running the demo application.
• Creates a Desktop shortcut for running the demo application.
• Checks whether JRE is present or not.
• Creates registry entries for uninstallability of application through Add/Remove programs.
• Makes the application uninstallable.