licence for a free scientific application

[fatecasino]

Hello,

there are a lot of license templates around. Before deciding for a a license you should ask yourself what your expectations are. Some questions that come into my mind:

• Do you want to provide source code or binary/executable only?
• Do you plan to provide a commercial license (maybe at some later time) in addition?
• Do you allow other developers to use parts of your source code in their projects (open source and/or commercial)? If so, would you like to set any restrictions to this usage ("Free beer" <-> BSD/MIT ... <-> GPL/LGPL license)?
• Which open source projects are you using and how do their license agreements match your ideas of a license?
• ...

For a comparison of free open source software licenses you may start with the Wikepedia comparison https://en.wikipedia.org/wiki/Compar...tware_licenses.

As you are already using Qt and qwt you surely have read their license agreements. For an application, you may start reading GPL version 2 or 3 license and check if they match your ideas.

If you have decided yourself for a license (either one of the well known ones or one designed by yourself) you should also check for legal implications (warranty, ...) of using this license. This depends on the country you live in. In general, not all sections of a license agreement are valid in all countries. If you decide for one of the well known licenses, you may check their acceptance by court in your country.

Best regards
ars

Thanks for your answer, your post arose some new questions. Ok, so,

• Do you want to provide source code or binary/executable only?

ars

I want to provide a binary/executable only

• Do you plan to provide a commercial license (maybe at some later time) in addition?

ars

I don't plan to provide a commercial license, I was just thinkg of selling commercially and extended/advanced version of the app

• Do you allow other developers to use parts of your source code in their projects (open source and/or commercial)? If so, would you like to set any restrictions to this usage ("Free beer" <-> BSD/MIT ... <-> GPL/LGPL license)?

ars

There won't be any open source code, just the executable

• Which open source projects are you using and how do their license agreements match your ideas of a license?

ars

Now here is the big thing...Help me understand. I have used Qt and Qwt. I suppose that their licence won't have a problem if I freely distribute my application. What happens if I want to sell my applications? Should I obtain a seperately a commercial licence by Qt and Qwt publishers? Another thing is that the .exe requires a copy of QtGui.dll, libgcc_s_dw2-1.dll, QtCore4.dll, QtGui4.dll in the same folder. Should I buy the commercial licence of each one of the publishers of these dlls?

[ars]

Hello,

when using Qt and qwt under the LGPL license there should be no problem in distributing your application (either free binary or selling and advanced version of your software). However, when going that way you have take special care of the implications of the LGPL license. In short, these are:

• link the libraries dynamically. This enables your users to replace the dynamic libraries with their own versions if they want to.
• Make sure you give credit to the open source libraries you use in Help/About dialog and documentation
• Make sure you distribute copies of the license together with your application
• Upon request, you have to provide the source code of the LGPL libraries (i.e. Qt and qwt) to your users. You do NOT need to provide the source code of your work.

So you should carefully read the LGPL licenses (version 2 or 3) to understand the implications of the license to your project and distribution model.

I have used Qt and Qwt. I suppose that their licence won't have a problem if I freely distribute my application.

You do not need to buy a commercial license of Qt for publishing your software as closed source (no matter if you freely distribute the binary or get a fee for it).

Besides Qt and qwt, you might also need to check the license conditions of your compilers runtime environment. In general, check the license conditions of any piece of software that you have not written yourself.

Best regards
ars

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Added after 8 minutes:

Hello,

when using Qt and qwt under the LGPL license there should be no problem in distributing your application (either free binary or selling and advanced version of your software). However, when going that way you have take special care of the implications of the LGPL license. In short, these are:

• link the libraries dynamically. This enables your users to replace the dynamic libraries with their own versions if they want to.
• Make sure you give credit to the open source libraries you use in Help/About dialog and documentation
• Make sure you distribute copies of the license together with your application
• Upon request, you have to provide the source code of the LGPL libraries (i.e. Qt and qwt) to your users. You do NOT need to provide the source code of your work.

So you should carefully read the LGPL licenses (version 2 or 3) to understand the implications of the license to your project and distribution model.

I have used Qt and Qwt. I suppose that their licence won't have a problem if I freely distribute my application.

You do not need to buy a commercial license of Qt for publishing your software as closed source (no matter if you freely distribute the binary or get a fee for it).

Besides Qt and qwt, you might also need to check the license conditions of your compilers runtime environment. In general, check the license conditions of any piece of software that you have not written yourself.

Best regards
ars

[fatecasino]

Hello,
However, when going that way you have take special care of the implications of the LGPL license. In short, these are:

• link the libraries dynamically. This enables your users to replace the dynamic libraries with their own versions if they want to.
• Make sure you distribute copies of the license together with your application

So you should carefully read the LGPL licenses (version 2 or 3) to understand the implications of the license to your project and distribution model.

would it be possible to explain further these two points.
When you say distribute, you mean that I should copy 2 seperate txt files, QtLicence.txt and QwtLicence.txt in the application folder?
I am sorry for asking, but I can't imagine myself getting into law related troubles (programming troubles are just enough )

[ars]

Hello,

When you say distribute, you mean that I should copy 2 seperate txt files, QtLicence.txt and QwtLicence.txt in the application folder?

Basically Yes. I' ve done it in the following way:

• I add a Licenses.zip file containing the license information for all open source projects I use in my project. This zip file contains several folders (one folder for each open source project) and the folders contain copies of the license files for the specific project. So one folder for Qt, another one for qwt, ... .
• Help/About dialog lists all open source projects used together with the license type and copyright information, something like "Qt 5.5.0, Copyright © 2015 The Qt Company Ltd., GNU Lesser General Public License 2.1" and so on. For details on the licenses I point the user to the Licenses.zip in the installation folder of my application.
• The user manual of my application repeats the listing of open source projects used (same as in Help/About) in the Copyrights section and points to Licenses.zip and a separate chapter of the user manual containing the license information. The latter is basically copying the license files into the user manual.
• When using GPL/LGPL projects don't forget to mention that you provide the source code of these GPL/LGPL projects upon request. You do not need to provide the code you have written yourself.

This procedure is required by our company lawyer when using open source projects in our company projects. It is motivated by the following section of LGPL 2.1:

You must give prominent notice with each copy of the work that the
Library is used in it and that the Library and its use are covered by
this License. You must supply a copy of this License. If the work
during execution displays copyright notices, you must include the
copyright notice for the Library among them, as well as a reference
directing the user to the copy of this License. Also, you must do one
of these things:...

Best regards
ars

[d_stranz]

Yes, this is excellent advice. Except for zipping the license files, I do the same in my commercial app - Help/About dialog, user manual, and license files installed to the program directory. I also supply links to the home pages of whatever open source libraries I use in my app. And unless the third-party license permits static linking, all open source libraries are delivered as DLLs.