Network services/Licensing approaches to network services

The following licenses try to address network services in some way or another.

Affero General Public License

The AGPL says that if you modify the software, your modified version must offer its source to users. It's written as a condition on modification because that activity is controlled by copyright law. The specific language (in section 13 of version 3) is:

Notwithstanding any other provision of this License, if you modify the Program, your modified version must prominently offer all users interacting with it remotely through a computer network (if your ersion supports such interaction) an opportunity to receive the Corresponding Source of your version by providing access to the Corresponding Source from a network server at no charge, through some standard or customary means of facilitating copying of software.

Honest Public License

The Honest Public License consists of GPLv2 plus an additional Affero-like term that was borrowed from a draft of GPLv3, made into section 2(d). This makes the approach effectively identical to the AGPL's. To the best of my knowledge, no software has been released under this license.

Open Software License/Academic Free License

The OSL defines setting up a web service to be "External Deployment," and says that when you externally deploy the software, you must follow the same conditions that apply to distribution as well.

This is stated as a condition of the entire license. The OSL tries to be a contract, so when that happens, it's possible that you could be compelled to follow this term no matter what you're doing with the software. However, the OSL is also meant to be usable as a copyright license, and in that case, the requirement could also hang on otherwise-private modification, as the AGPL does.

All this analysis applies to the AFL as well; the two licenses differ in other respects.

5. External Deployment. The term "External Deployment" means the use, distribution, or communication of the Original Work or Derivative Works in any way such that the Original Work or Derivative Works may be used by anyone other than You, whether those works are distributed or communicated to those persons or made available as an application intended for use over a network. As an express condition for the grants of license hereunder, You must treat any External Deployment by You of the Original Work or a Derivative Work as a distribution under section 1(c).

Common Public Attribution License

The CPAL is a modified version of the Mozilla Public License, adding a couple of noteworthy requirements. One of them is an "external deployment" section. The language is clearly borrowed from the OSL; it has been modified only to make references to other parts of the MPL. It says:

15. ADDITIONAL TERM: NETWORK USE.

The term "External Deployment" means the use, distribution, or communication of the Original Code or Modifications in any way such that the Original Code or Modifications may be used by anyone other than You, whether those works are distributed or communicated to those persons or made available as an application intended for use over a network. As an express condition for the grants of license hereunder, You must treat any External Deployment by You of the Original Code or Modifications as a distribution under section 3.1 and make Source Code available under Section 3.2.

Reciprocal Public License

The RPL simply requires you to make source available to anyone who can run the software remotely. It's not clear how they require the recipient to do this; if pressed, I'd guess that the authors would argue that the RPL is a contract that the recipient must accept to use the software at all. The section with this specific requirement says:

6.1 Availability of Source Code. You must make available, under the terms of this License, the Source Code of any Extensions that You Deploy, via an Electronic Distribution Mechanism. The Source Code for any version that You Deploy must be made available within one (1) month of when you Deploy and must remain available for no less than twelve (12) months after the date You cease to Deploy. You are responsible for ensuring that the Source Code to each version You Deploy remains available even if the Electronic Distribution Mechanism is maintained by a third party. You may not charge a fee for any copy of the Source Code distributed under this Section in excess of Your actual cost of duplication and distribution of said copy.