DMelt:Dev/License Information

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License information

The license topic of DataMelt is complex and requires a good understanding of several issues. A short description of the license is given here.

A complete license information for end-users is given here. Click on the "Agreement" link. Below we will consider a more complicated case when DataMelt is used by developers for for-profit organizations.


Many components of DataMelt are free. But many services (including the full access to this manual) and jar components are only accessible for full members. The yellow components shown on this diagram are free and protected by the GNU (v3) public license.

Man:general:dmelt graph.png

Other components (blue with red text) are only acceptable for full members.


DataMelt libraries

The main core libraries (jhplot and jehep package and other used by these libraries) are licensed by the GNU General Public License v3. This means that one __can__ use it to develop a commercial product and sell it. Read this article for explanation. However, the derived works can only be distributed under the same license terms, i.e. this license is not suitable for commercial applications with closed-source environment. What does it mean? Falling under GPL does not mean you have to publish your code on the web. You should provide it only when a person having the license asks for it.


DataMelt documentation

All documentation packages and online-services are included using DataMelt language files, documentation, examples, installers, code-assist databases and certain third-party libraries are subject to the Creative Commons Attribution-Share Alike License 2.0.

You are free to copy, distribute, transmit, and adapt DataMelt under the following conditions:

  • Attribution. You must attribute the work i.e. by linking to http:jwork.org/dmelt
  • Non-commercial. You may not use this work for commercial purposes. Please become a full DataMelt member using the member login page. After the registration, you can obtain a professional edition of DataMelt suitable for commercial usage. It should be noted that the source code will remain under the terms of the GNU General Public License.

DataMelt libraries with permissive licenses

If you are not happy with the restrictions of the GPL license, consider using a redesigned DataMelt with business-friendly licenses, such as LGPL, MIT, Apache v2, BSD. The documentation packages and online- services will converted from the Creative Commons Attribution-Share Alike License (for non-commercial usage) to a commercially-friendly license.

You will need to send an email to dmelt@jwork.org asking about such DataMelt version. We provide business-friendly DataMelt for a small price.



Note on included jar packages

All jar libraries submitted to the DataMelt by the users are compatible with the open-source GPL licenses and available in the public domain. However, if you note a package which is not consistent with a public domain license, please inform us and we will remove such library.


Examples of DataMelt license usage

Here are several typical examples showing the DataMelt covering several license questions:

  1. A student prepares his homework using DataMelt, or an academic professional uses DataMelt for a scientific paper. DataMelt is totally free in this case. However, an access to documentation describing advanced usage may still be needed. Thus, it is recommended to get the membership account and pay the fee to have the full access to the documentation and help system.
  2. A software company is developing a code for a other (client) company. This company can use the DataMelt jar libraries without any restrictions, as long as the final product for the client has a similar the original GPL license. This means the derived product should be under the GPL (open source).
  3. A company is performing an analysis of financial market. As in the previous case, DataMelt IDE is not free. Also, these will be no access to DataMelt documentation (manual, API, examples). Each developer should purchase the license for a commercial usage, which will also give an access to the full documentation.
  4. A company is developing a commercial product with closed source code. In this case, you cannot use the original DataMelt version. You should request a redesigned DataMelt with business-friendly licenses (LGPL, MET, Apache,etc.).


I want to protect all source code!

Some people ask: what if my company will decide to rewrite this project and alter the license? Technically, this going to be a very expensive project. DataMelt has more than 100M of source code files which are all need to be rewritten. Even a large company hardly can afford doing this. It is certainly almost impossible to be competitive with hundreds of academic users writing scientific software and contributing to the development of this package. The bottom line: request DataMelt with commercially-friendly licenses that allow to ship your product without providing source code. But do not alter business-friendly DataMelt licenses (they will be provided to you by the DataMelt team).


--- jWork.ORG team 2015/12/02 19:52

More information on this topic is in DMelt books