Rational ClearCase is a tool for software configuration management (SCM). Once it hit the market in early 1990s, it was a revolutionary tool. One of the most remarkable features were dynamic views, which enabled viewing different versions of a product without downloading the files to the developer's computer.
Since then, ClearCase powers software development in many large- and medium-size enterprises. However, since IBM purchased Rational in 2003, development of new features slowed down, and the new generation of developers switched to new tools, like Git.
Recently, IBM entered into a partnership with HCL, which hopefully will bring about development of new ClearCase features. Let's wait and see...
Before ClearCase, there was essentially no configuration management, and a developer often did not know which version of the product was most recent, what was delivered to what client and on what version were his colleagues working.
Imagine a group of programmers that write some software, delivers it to a customer and then continues to develop new features. All of the sudden the customer reports a bug. What do you do? How do you find the version delivered to him? Your software is already changed but the development of the new release is not yet completed.
OK, responsible team leaders used to do some manual management, like keeping each version of the software in a separate folder. But it was very inconvenient.
For example, if I fixed a bug in an old version, there was no easy way to apply that solution to the new development (which quite probably, it had inherited that bug).
Therefore when we started using ClearCase, it was like a miracle. It saved all versions of your software, it let you tag releases, it gave tools for parallel development and much more.
