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Lessons From Six Software Rewrite Stories (medium.com)
A new take on the age-old question: Should you rewrite your application from scratch, or is that "the single worst strategic mistake that any software company can make"? Turns out there are more than two options for dealing with a mature codebase. Herb Caudill: Almost two decades ago, Joel Spolsky excoriated Netscape for rewriting their codebase in his landmark essay Things You Should Never Do . He concluded that a functioning application should never, ever be rewritten from the ground up. His argument turned on two points: The crufty-looking parts of the application's codebase often embed hard-earned knowledge about corner cases and weird bugs. A rewrite is a lengthy undertaking that keeps you from improving on your existing product, during which time the competition is gaining on you.
For many, Joel's conclusion became an article of faith; I know it had a big effect on my thinking at the time. In the following years, I read a few contrarian takes arguing that, under certain circumstances, it made a lot of sense to rewrite from scratch. For example: Sometimes the legacy codebase really is messed up beyond repair, such that even simple changes require a cascade of changes to other parts of the code. The original technology choices might be preventing you from making necessary improvements. Or, the original technology might be obsolete, making it hard (or expensive) to recruit quality developers.
The correct answer, of course, is that it depends a lot on the circumstances. Yes, sometimes it makes more sense to gradually refactor your legacy code. And yes, sometimes it makes sense to throw it all out and start over. But those aren't the only choices. Let's take a quick look at six stories, and see what lessons we can draw.
For many, Joel's conclusion became an article of faith; I know it had a big effect on my thinking at the time. In the following years, I read a few contrarian takes arguing that, under certain circumstances, it made a lot of sense to rewrite from scratch. For example: Sometimes the legacy codebase really is messed up beyond repair, such that even simple changes require a cascade of changes to other parts of the code. The original technology choices might be preventing you from making necessary improvements. Or, the original technology might be obsolete, making it hard (or expensive) to recruit quality developers.
The correct answer, of course, is that it depends a lot on the circumstances. Yes, sometimes it makes more sense to gradually refactor your legacy code. And yes, sometimes it makes sense to throw it all out and start over. But those aren't the only choices. Let's take a quick look at six stories, and see what lessons we can draw.
The articles own facts don't support the article's conclusions.
"Netscape’s slide into irrelevance wasn’t entirely due to the rewrite—a court agreed that Microsoft had deliberately abused their monopoly. But the rewrite was certainly a contributing factor"
The graf accompanying this section shows Netscape's market share dropping from about 80% to 50% BEFORE the rewrite. Now that drop continues from 50% to near 0% during and after the rewrite, so the rewrite certainly did not save Netscape. But the slope of the decline barely changes pre- and post-rewrite. Basically, unless there's other evidence not presented, the best conclusion is the rewrite had no effect.
Also, "what finally ended the IE6 era wasn’t Firefox but Google Chrome."
Except your own graf shows IE market share dropping starting in late 2002 in mirror to the rising Mozilla/Firefox. Chrome doesn't even show as a factor until 2008. The articles own facts don't support the article's conclusions.
What really killed Netscape was releases a lousy product. 4.0 suuuuucked. (Folks on the web in '96/97 remember.) And IE at the time was releasing it's first good version, a better version. Fact is, at that time IE was better than Netscape.
What Netscape needed was a better product, and if it took a ground-up rewrite to get that better product, then a rewrite was necessary.
What we know now is the rewrite did not save Netscape. But we'll never know if there was some other course of action that could have saved the it. What we really should be doing is examining what was going on in '95/'96 to produce such a bad product and lose that market share in the first place, not at what rearrangements of the deck chairs was done as the ship went down.