What causes a computer program to turn into a Big Ball of Mud? Is it possible to recover from this anti-pattern? Are there proven refactoring methods that can be applied?
A Big Ball Of Mud normally occurs because of one of the following:
Change of Requirements - You architect a solution with one set of requirements, which over time change and now, you are probably catering to a different audience who wants to use the same product with slightly different requirements. You bake those requirements into the same product and you end up with a BBOM.
Change of Developers - The original product has been created by one set of developers with certain design and architectural assumptions which are not entirely evident to a whole new set of developers who 'take over' the product for maintainence or further development. The new developers make their own assumptions and over time, the product degrades into a pile of unmaintainable junk.
Incompetency - of the developers (they are unaware of anti-patterns), the management (too demanding, lack of knowledge of the product) or the users (they don't really know what they need). This is hard to solve.
Sometimes, the best solution is simply to rewrite the application catering to the new requirements. But this is normally the worst case scenario. The cumbersome solution is to stop all new development, start by writing a set of tests and then redesign and rearchitect the whole solution. This could take years, depending on the size of the product, though.