As stewards of the Eclipse Public License (EPL-1.0), the Eclipse Foundation provides materials to help you understand and apply the EPL-1.0 license. Materials made available by The Eclipse Foundation regarding the EPL-1.0 should be considered your primary source for information about the license.

See Eclipse Public License (EPL) Frequently Asked Questions

The FAQs below are intended to help community members in applying the EPL-1.0 license in the context of OpenDaylight.

Note that any words, other than proper names, that are capitalized in this FAQ are terms that are defined in the EPL-1.0.

  1. What is the license for OpenDaylight?
  2. Does the EPL-1.0 apply to all OpenDaylight Contributions?
  3. Does OpenDaylight require Contributors to assign Contributions?
  4. Does OpenDaylight accept code made available under other Open Source licenses?
  5. Does OpenDaylight have a patent policy?
  6. Do I grant a patent license if I merely distribute unmodified OpenDaylight code to others?
  7. I have heard that the Eclipse Public License is a “weak copyleft” license.  What does that mean?

What is the license for OpenDaylight?

Each of the separate OpenDaylight projects designated in the development environment as a Program is made available under the EPL-1.0 as a separate Program.  OpenDaylight’s Programs may be made available or distributed in a variety of different combinations, but, for purposes of the EPL-1.0, each reference to a Program is a reference to the separate functional blocks designated as Programs in the development environment.

OpenDaylight Programs may incorporate other open source projects made available under licenses that permit redistribution of the project under the EPL-1.0.

If, for any reason, OpenDaylight wanted to make a Program available under a license other than the Eclipse Public License, the OpenDaylight Board of Directors would have to formally approve the use of an alternative license and the licensing for that Program would be clearly indicated.

Does the EPL-1.0 apply to all OpenDaylight Contributions? 

Yes.  EPL-1.0 is the license applicable to all Contributions to OpenDaylight.

EPL-1.0 specifically provides for each Contributor to grant a copyright and patent license for that Contributor’s Contribution directly to each individual Recipient.  There are several points to note here.

One point is that Contributors do not assign any intellectual property rights and do not intend to vest any rights in anyone else other than through the express license to their separate work set forth in EPL-1.0.

Accordingly, the Contributor granting the copyright license retains ownership of its separate copyright in its Contribution.

Another point is that each Contribution is separately licensed by the Contributor that authored or owns the copyright in the code.  Thus all Recipients receive the same copyrights from the original Contributors regardless of the path that the code may have followed.

The Contributor grants a license only to Licensed Patents for use of the specific expression of functionality embodied in the source code and/or corresponding compilations thereof, Contributed by that particular Contributor and (i) that are owned by the Contributor or (ii) that the Contributor may license on a royalty-free basis consistent with the requirements of the EPL-1.0.  Each Recipient receives the same patent license from each individual Contributor only with respect to the code contributed by such specific Contributor. These rights are established upon the date of the Contribution.

A Contribution can be made by an individual copyright holder or by an employee of a corporate copyright holder or by someone acting on a corporate copyright holder’s behalf, with the necessary permissions or authority from the copyright holder (i.e. an independent contractor engaged for the purpose of performing development work under the corporate copyright holder’s direction.)  Individual developers, committers and project leads who are employed by different corporate Contributors are not acting on behalf of any other participant in the project merely because they work cooperatively and collaboratively.

The license grants are specifically structured in this way to encourage Contributions and to ensure that all Recipients of the same source code receive the same intellectual property rights.  The license makes it clear that, except with respect to these expressly stated licenses, Contributors do not have to be concerned about assignment or waiver of intellectual property rights.  Nor do they have to worry that other licenses may be implied or that Contributions to OpenDaylight may interfere with their right to assert patents against others who are not operating within the scope of the license.  All Contributors grant the licenses as expressly stated and all Recipients receive the licenses that are expressly provided.

Does OpenDaylight require Contributors to assign Contributions?

OpenDaylight does not require Contributors to assign any intellectual property to OpenDaylight.  All Contributors retain separate ownership of all intellectual property rights in their Contributions.  Contributions are licensed to OpenDaylight under the EPL-1.0.

Contributions to OpenDaylight Programs are made through specially designated committers in accordance with the process described in the Developer Wiki.

Does OpenDaylight accept code made available under other Open Source licenses?

OpenDaylight Programs are made available under the EPL-1.0.  Committers may propose incorporation of code from other open source projects only if the license applicable to that open source project permits the code to be distributed under the terms of the EPL-1.0.

What other open source licenses permit redistribution of the project under the EPL-1.0?   Many people divide open source licenses into two categories:  copyleft licenses and permissive licenses.

Copyleft licenses do not permit redistribution of the copyleft-licensed code under a different license.  A copyleft license only permits redistribution of the copyleft-licensed code under the same license.  GPL-2.0 and GPL-3.0 are examples of copyleft licenses.  The Eclipse Foundation, the license steward for the Eclipse Public License, has provided guidance regarding the compatibility of the EPL-1.0 and the GPL family of licenses.  See http://www.eclipse.org/legal/eplfaq.php#GPLCOMPATIBLE.

Permissive licenses do permit redistribution of the permissively-licensed code under a different license.  There are many examples of permissive open source licenses.  Among the most popular are the BSD 2-Clause, BSD 3-Clause, MIT and Apache Licenses.  Code licensed under these licenses could be incorporated into an OpenDaylight Program and the entire Program could be distributed under the EPL-1.0.  Thus committers may propose incorporation of code licensed under permissive licenses for use in an OpenDaylight Program.  Non-copyleft licenses that impose obligations beyond the attribution and documentation requirements found in these popular permissive licenses will be reviewed on a case-by-case basis.

The same guidance applies to code that, while not proposed for incorporation into an OpenDaylight Program, is a dependency required for the intended use of an OpenDaylight Program.  While the dependency itself need not be distributable under the EPL-1.0, the license applicable to the dependency must be one that permits the proposed usage while still allowing the Program to be distributed under the terms of the EPL-1.0.  If you have any questions about a particular dependency required as part of your Contribution, please contact inbound@opendaylight.org.

Does OpenDaylight have a patent policy?

Just like the Eclipse Foundation, OpenDaylight’s policy on patents is embedded in the terms of the Eclipse Public License.

See http://www.eclipse.org/legal/legalfaq.php#use_10.

Do I grant a patent license if I merely distribute unmodified OpenDaylight code to others?

No.  License grants are made by Contributors.  See Does the EPL-1.0 Apply To All Contributions  above.  As with many other open source licenses (such as GPL v. 3), the patent license is not determined by what code you distribute.  It is based on the specific Contributions of a specific Contributor.  This makes it possible for companies and their employees to engage with the project without fear of inadvertently granting an unauthorized patent license by redistribution of code.

I have heard that the Eclipse Public License is a “weak copyleft” license.  What does that mean?

That term “weak copyleft” is not a precisely defined term of art so it is not very helpful in understanding your sharing obligations under the EPL-1.0.  But commonly we see people referring to the EPL-1.0’s additional permissions regarding the distribution of object code versions of Eclipse licensed Programs and the clarity around the use of Application Programming Interfaces to make connections with Eclipse licensed Programs.  The Eclipse Foundation, the license steward for the Eclipse Public License, makes it clear that “merely interfacing or interoperating with Eclipse plug-in APIs (without modification) does not make an Eclipse plug-in a derivative work.”  See http://www.eclipse.org/legal/eplfaq.php#EXAMPLE.