While as Vaadin Framework and 95% of the add-ons are free and open source with a liberal Apache -license, there are also a handful of commercial or dual-licensed add-ons also - most notably Vaadin Pro Add-ons. We have been and will continue to be really careful to keep these as add-ons - something that add value and are truly optional - not something that anyone is forced to use. That said - we hope to be able to make them tempting enough to get anyway :)
The commercial license for the add-ons is called Commercial Vaadin Add-on License 1.0. It can be summarized as - all developers who commit to a project using the add-on must have a license. It turns out that the license terms were a bit too vague and could be interpreted so that a wider number of developers than we intended should have a license. In order to alleviate this concern we are in process of releasing version 2 of the license.
Commercial Vaadin Add-on License 2 is essentially the same license, but with clarifications in the language to make sure that the need for the license doesn't spread in the organization wider than the scope of the developers building Vaadin based user interface (UI). For the exact formulation of the language, see the license text. As a summary - a developer needs a license when he either directly or indirectly uses an add-on in a project he is working on.
Here is an example to clarify the picture: Joe and Mary are building a backend for an invoicing system while Bob and Mike are writing the UI with Vaadin. UI uses Timeline add-on to visualize cashflows over time. In practice Bob wrote all the code for this fancy visualization view. The team designs the system with best practices in mind and the backend code does not depend on UI. In fact, the same backend is used for integrating other systems through REST APIs. Question - how many licenses the team needs to Timeline? With the old V1 license, all members of the team could have been interpreted to need a license, but with V2 license just Bob and Mike need a license. Note that even though Mike did not use Timeline directly, his code calls (indirectly) Timeline API:s through the code that Bob wrote. Because the backend did not even import UI classes, Joe and Mary do not need a license. Simple, huh?
What happens if the team subscribes to Vaadin Pro Account? Pro Account includes licenses to all Pro Add-ons. If in our example both Bob and Mike would have subscribed to Pro Account, no Timeline licenses would have been needed in addition to the Pro Account. But while as CVAL licenses purchased from the Directory are valid for ever - Pro Account is a monthly subscription.
A valid "optimization" could be to get Pro Account subscriptions for the frontend developers during the project and after the project is completed only keep Pro Accounts active for the developers maintaining the code. Or one could even quit all the Pro Accounts after the project and purchase "eternal" licenses for the maintainers to the add-ons used in the project.
Versions of the Pro Add-ons with new CVALv2 license will be submitted to Directory shortly after summer vacation. Everyone with CVALv1 licenses can upgrade to these new add-ons without any extra cost.
If you have any questions or comments about add-on licensing, join the discussion on a forum thread about the topic.