Integrating Open Source Libraries

There are a few things that one should consider when using and integrating an open source library into your application:

  1. What are the licensing terms for the library? There are some liberal licenses that mostly let you do anything you want. The MIT license is an example of a very permissive license. Other licenses may provide a number of restrictions. Can you integrate with closed-source software? Can you distribute binaries without the source? Do you need to put some kind of attribution somewhere in your software? Another thing to look our for are the so-called viral licenses. Viral licenses specify that if you integrate their code into your system, then the terms of that license apply to your own software as well. These can be very dangerous from the standpoint of a company developing a commercial product. The most well-known example of such copyleft licenses is the GPL. Integrating GPL code into your system will often mean your software needs to be open source as well. While more open source is good, it may not be in the best interest of your company, so tread lightly.
  2. Which version of the library will you use? Many open source libraries will release updates on a regular basis. There may be some compatibility issues depending on the version you use. For example the popular open source CMS WordPress releases regular updates. If you are integrating with WordPress, you need to decide which version you are supporting. You will also need a plan for upgrading to future versions and ensuring compatibility. (See the next item.)
  3. How will you handle bugs and updates in the version you’ve chosen? It’s happened that our system was having problems due to a bug in an open source Javascript rich text control library. After investigating, we found that a fix was available but was only applied in a future version. Upgrading to that future version would require that we test the entire system for compatibility problems. That was out of the question. I ended up having to apply a fix to our local version only. This meant that we now had a different version from the “official” released version. This may lead to further compatibility problems in the future. You should also be aware of licensing issues here too. The license may require that you submit any modifications to the community as open source contributions.
  4. Is there an active help and support system for the software? The demands of enterprise software development often need timely support. There was a time we had to use a certain open source document management system. We later discovered that it was very hard to get help on any issues encountered, either from official channels or the community. This led to many difficulties and issues in that project. You might also want to check popular programming forums such as StackOverflow. Check how many questions about that library usually remain unanswered. If the number is low, that’s a good indicator that you might have trouble looking for help later on.
  5. What dependencies does the library have? You might want to make sure the dependencies don’t have any problems with the previous items above.

The great thing about modern software development is that we have a large number of open source libraries available to use and draw inspiration from, but that doesn’t mean you can just willy-nilly pick up just any library. The above questions provide a good starting point for evaluating open source libraries for your use.

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