The commercial application of the General Public License would endeavor to protect the business, like any software license. In stark contrast to much of what is said about the GPL on the internet, the GPL is ideal for this purpose.
Some software packages depend on their use by developers, via SDK or source code, for their general success. In these cases, it is rational to publish the source code as the ultimate SDK. When in doubt, read the source. Have a problem, fix the source and share a patch or change request. Discuss the implications, engage and interact, and the changes may be accepted into the original package. The GPL excels with this, and was designed for this. Furthermore, the GPL has been proven in sustaining this.
The copyright holder is free to license the software under alternative licenses, as necessary.
Protecting the business may require additional measures, which the GPL also accommodates without modification or addenda.
"Nothing in this License shall be construed as excluding or limiting any implied license or other defenses to infringement that may otherwise be available to you under applicable patent law."The copyright holder may file patents related to the critical processes implemented by the software in order to further protect the software from commercial reproduction. The patent and the GPL licensed software publication is a finished package completely described by the GPL.
Licensees in good standing under the GPL have a license to the patent exclusively embodied in the published and protected software.
In this way, a business in the software is protected while the software is published in open source. Making this model work in terms of revenues will require additional supply side value, and demand for that value. This value is typically support in the practical use of the package as productive and reliable.
In many commercial situations, support is important. There is very low tolerance for inconvenience as a distraction from productivity. Conversely, there is substantial demand for convenience as supports productivity.
The first component of such a commercial offering would be a commercial software distribution network. With a convenient and productive process, the commercially agreed installation is effected and maintained.
The second component would be the interactive human contact covering each aspect of the setup and use of these installations.
These services are worth money, and productive businesses will pay for them. The software itself is virtually irrelevant -- it is virtual -- in the business relationship. These requirements must be met before much of the software product itself becomes relevant to the business relationship.
I explain this via the economics of computing, which is effectively modeled in terms of productivity. Business managers and operators will rationally choose the best available productivity subject to the best available preservation of their processes and relationships. A new element of their processes is introduced only rarely, and must successfully prove itself to have superior productivity and reliability over all practical use cases. In the business environment, a software package can compete with a screwdriver, printer, wall clock, or whiteboard. Any kind of thing on which known effective processes have been based. It's not easy to best a screwdriver in its reliability, but the screwdriver can be beat in terms of productivity.
The analysis of this thesis depends on a few critical points.
First: the law can protect copyrights, patents and contracts. Of course, particular issues and disputes are beyond the general scope.
Second: the consumer demand is significant to substantial in the operational productivity of the product with respect to the operation of the consumer's business. This point has potential interaction with a consumer IT (IS) department -- however, these effects are typically a net contribution to demand (technical sale).
Third: most importantly, business replication (by competitors) in terms of services is not legally protected by this framework -- at least not before relevant agreements are established. Economic protections include the value of name recognition as a source of competence and support, while business mass, velocity and acceleration are the ultimate factors. Naturally, these metaphors refer to revenue and the first and second derivative changes in revenue over time.