2. Partners & OEMs
Some ISVs, SIs (systems integrators), and device manufacturers may want to use open source software within their final product without having to open source the product's software. In this situation, the GPL in conjunction with a commercial license will result in higher open source vendor revenue than the ASL in conjunction with a commercial license.
It's interesting that device manufacturers such as Cisco and Western Digital are using GNU/Linux in their products and are opting to open source their software versus paying a license fee and keeping their software private. I believe that device manufacturers will increasingly open up their software in ways that encourage the interested/skilled user base to tinker. From a device manufacturer standpoint, I'd argue there is little OSS vendor revenue difference in using the GPL vs. ASL.
Next, let's consider ISVs and SIs. On one hand, you could argue that since software is going to be increasingly delivered through the mythical cloud, the GPL's role as a stick to encourage a license purchase will diminish. But I don't believe that the enterprise world is moving to SaaS as fast as the hype would suggest. For years, if not decades to come, the vast majority of ISV- and SI-delivered applications will be distributed to enterprises and installed on corporate servers as they are today. As such, the GPL's role in driving open source vendor revenue from ISVs and SIs will remain an important reason to select the GPL.
3. Hostile competitors
The final reason to use the GPL over the ASL is that the GPL provides better protection against competitors, especially larger ones, using the OSS code to go up against the open source vendor in question. However, I could quote examples of GPL- and ASL-licensed open source products that have been forked to varying degrees by larger competitors. In the two situations that come to mind, it can easily be argued that the forks have been unsuccessful. The open source vendor's brand has proved to be a more realistic barrier to entry than the license was thought to be.
I can think of only one business reason that an open source vendor would select the GPL over the ASL -- namely, the revenue opportunity from ISVs and SIs who would rather pay for a commercial license than have to open source their own applications.
What do you think?
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p.s.: I should state: "The postings on this site are my own and don't necessarily represent IBM's positions, strategies, or opinions."