On software Installation under Windows

Don't want to sleep at night, study the principle of software installation under the Windows system.

Most basic, installing a software will copy the required files to the destination address. If this is the only step, the software can be used, then the software can be called pure green software. This step is a step in any software installation.

Some software installation, will also copy some DLLs to the system directory, so I think because there will be other programs to share these DLLs. Otherwise, you just need to put the DLL and the software execution file in the same directory, execute the file can access to the DLL. At least for the DLL of the function library, it is not clear to me that this is the case for COM. Speaking of which, reminds me of some software installation also need to register some DLLs, as for why to register, I only know that the function library type DLL does not need to register, and COM needs to register, or the system will not be able to access. Why does COM have to register to access it? This, because I do not know the COM very well, so I can not talk nonsense. In fact, the system is registered more DLLs, the system will become slow, so should be those that are no longer required to register the DLL. How to know which DLLs are useless, you can see in the registration table shared DLLs are used by several programs. This is the principle of cleaning up redundant DLLs in Windows Optimizer master.

In addition, many software installations will write some values to the registry. This is probably the user's some settings, registration information and so on.
Finally, before the software installation is complete, in order to facilitate the user to access the software, the installer will also put the program group in the Start menu, place the shortcut on the desktop, of course, this is generally optional.

Another problem is that some software needs to be restarted when it is installed. The reason, in short, is to replace the files that the system is using during the installation process. Before restarting, Windows changed the new file to another name in order to coexist with the old file. After the restart, Windows replaces the old file with the new file based on the recorded information. Some software uninstall also need to restart, because the uninstall process to delete the system is using the file.

In fact, I very much hope that all the software is released in a compressed package, like a lot of users do the green free installation version, with batch to complete the copy of some files to the system directory and write the registry value of the task. The advantage is that after the system re-installed, do not like reloading software as the copy file to the destination address, just a few mouse, the software can be used again. Is it not good to reduce the number of write disks and also to reduce disk fragmentation?

1:06 2007-5-30

On software Installation under Windows