I recently came across the Transitive Grace Period Public License (alternate link) by Zooko Wilcox-O’Hearn.  I fonud it interesting because it’s very similar — almost identical — to something I had first starting floating about ten years ago.  I called it the Temporary Proprietary License (TPL).  I’m sure this is a case of “great minds think alike”.  One things that I like about my write up is that I gave some of the rationale behind why this approach is a fruitful one:

A while ago, I was talking to Jim Gettys at the IETF meeting in Orlando, and the subject of software licensing issues came up, and he had a very interesting perspective to share about the X Consortium License, and what he viewed as bugs in the GPL.

His basic observation was this: Many companies made various improvements to the X code, which they would keep as proprietary and give them a temporary edge in the marketplace. However, since the X code base was continually evolving, over time it became less attractive to maintain these code forks, since it would mean that they would have to be continually merging their enhancements into the evolving code base. Also, in general, the advantage in having the proprietary new feature or speed enhancement typically degraded over time. After all, most companies are quite happy if it takes 18-24 months for their competitor to match a feature in their release.

So sometime later, the companies would very often donate their previously proprietary enhancement to the X consortium, which would then fold it into the public release of X. Jim Gettys’ complaint about the GPL was that by removing this ability for companies to recoup the investment needed to make major developmental improvements to Open Source code bases, companies might not have the incentive do this type of infrastructural improvements to GPL’ed projects.

Upon reflection, I think this is a very valid model. When Open Vision distributed the Kerberos Administration daemon to MIT, they wanted an 18 month sunset clause in the license which would prevent commercial competitors from turning around and bidding their work against them. My contract with Powerquest for doing the ext2 partition resizer had a similar clause which kept the resizing code proprietary until a suitable timeout period had occurred, at which point it would be released under the GPL. (Note that by releasing under the GPL, it prevents any of Partition Magic’s commercial competitors from including it in their proprietary products!)

For more, read the full proposal.