Software Deployment

Legacy software installations in the past were developed in a variety of ways. Setup developers designed their install programs to concentrate on their own products which often impacted on programs that were already installed on the PC.

With legacy installations in the past, there might be two applications using the same file, but one might be designed to run on an older version.

This led to “DLL hell” where the installation/uninstallation of one application would cause other applications to stop working

Hi,

In simple words :)

For instance there is an application (A) with the dll version 1.0 which is already installed on the machine, there is another application (B) with the same dll name but different version, let us take it as 2.0.
When the application B is installed on the system which has App A installed, it overwrites the dll file to version 2.0 and if the app B is uninstalled the Dll also gets uninstalled, hence failing to launch Application A as well.

This conflict between the dll file is know as DLL hell.

I am not pasting the page in, read the link

http://en.wikipedia.org/wiki/DLL_Hell

Jagadeish has explained it well. Just wanted to say that there is a tool called Conflict Manager which comes with WISE package Studio which can be used to detect DLL Hell issues. Also Merge Modules and following some component rules can help resolve DLL Hell.

By using Merge modules also we can resolve the Dll Hell problem.