License proliferation has been a hot topic amongst the open source community for the past couple of years. I am happy to report that the Eclipse Foundation and IBM have collaborated to do our bit to help by superseding the Common Public License (CPL) with the Eclipse Public License (EPL). This means that the CPL will no longer be considered an active open source license.
Perhaps the best way to explain this is via a Q&A:
1. What was actually done?
There was a two step process that was followed to make this happen. First, following the terms of the CPL, IBM assigned the responsibility to serve as the Agreement Steward of the CPL to the Eclipse Foundation. Second, the Eclipse Foundation officially recognized the EPL 1.0 as the new version of the CPL 1.0. In OSI license terminology, the EPL now supersedes the CPL.
A quick read of the two licenses will quickly show that they are very very close. Other than their names and (previously) their Agreement Stewards, the only substantive difference is the breadth of the patent license termination in the event of a patent law suit. (See the second paragraph of Section 7.) For more information on the relationship between the CPL and the EPL see the EPL FAQ.
2. What does this actually mean?
For those projects that are currently using the CPL and wish to continue using it, not much. However this will open up an additional option for those CPL-licensed projects wishing to migrate to the EPL.
Using OSI’s classification of licenses, it means that the CPL will move from the “Licenses that are popular and widely used or with strong communities” to the “Superseded licenses” category as maintained by the OSI. It does not mean that the CPL has disappeared. However, it is the recommendation of the OSI, IBM and the Eclipse Foundation that new projects use the Eclipse license rather than the CPL if this “style” of license appeals to you. See below for more details if you have an existing CPL-licensed project.
3. Why was this done?
License proliferation in open source is a real issue. It costs businesses to review multiple licenses, and the plethora of licenses can be confusing to someone starting a new open source project.
Over the past five years we have seen the Eclipse Foundation go from a good idea that might work to one of the most successful open source communities out there. We have seen the Symbian Foundation adopt the EPL as its license, thereby bringing a huge community and code base in its own right to the EPL, plus demonstrating the utility of the license well outside of the Java domain that it is best known in. More recently, Google also added the EPL as one of the licenses it supports on Google Code. It is clear that if we wanted to consolidate on one license, that the EPL made the most sense.
4. I have a CPL-licensed project. What do I need to do?
You can continue to use it if you want to, although the whole reason we’re making this happen is because we wanted to provide projects with an easy option to migrate to the EPL to help reduce license proliferation.
There is a very simple path to moving your CPL-licensed project to the Eclipse Public License. Since the EPL has been denoted as the successor version of the CPL, you can use a provision in Section 7 (“In addition, after a new version of the Agreement is published, Contributor may elect to distribute the Program (including its Contributions) under the new version.”) to easily switch to the EPL.
5. When does this take effect?
6. Wait a second! The CPL also says “Each new version of the Agreement will be given a distinguishing version number.” How can the EPL 1.0 be a new version of the CPL 1.0?
Well, you’re right. We could have created a CPL 1.1 that simply pointed to the EPL 1.0. But frankly that seemed a lot more confusing than helpful. Especially since the licenses effectively differ by about one-and-a-half sentences. However, more importantly, the EPL is indeed the successor version to the CPL. The Eclipse Foundation and its members developed the EPL from the CPL by modifying those one-and-a-half sentences. The name of the license doesn’t change that history.