Software Licensing and Development Tools
This domain covers how software may legally be used, copied, modified, and redistributed, plus the tools programmers use to build it. The exam tests your ability to read a licensing scenario and state what the user may and may not do, and to match a development task to the correct tool. Expect questions about EULAs, open-source obligations, and the difference between an IDE, a compiler, and a debugger.
Licensing models
- Proprietary perpetual licences grant use indefinitely under an EULA, usually per device or per named user.
- Subscription and SaaS licences grant use only while payments continue; SaaS keeps the software on the vendor's servers.
- OEM licences are bound to the hardware they shipped with and generally cannot be moved to a new machine.
- Site and concurrent licences allow many installations but limit simultaneous users.
- Freeware is free of charge but closed source; public domain works have no rights reserved.
Open-source licences
- Permissive licences such as MIT and Apache permit modification and closed redistribution, usually with attribution; Apache also grants patent rights.
- Copyleft licences such as GPL require that distributed derivative works be licensed under the same terms and include source code.
- LGPL permits linking from proprietary programs under conditions; AGPL extends obligations to network use.
Development tools
- Editors and IDEs support writing code; IDEs bundle editing, building, and debugging.
- Compilers translate whole source files ahead of time; interpreters execute line by line.
- Linkers combine object files and libraries; loaders place the program in memory.
- Debuggers, profilers, version control (Git), SDKs, and APIs support testing, performance work, collaboration, and integration.
Worked example
A firm modifies a GPL-licensed tool, embeds it in a product, and ships the product to customers. Reasoning: shipping binaries counts as distribution, which triggers GPL obligations, so the firm must offer the complete corresponding source under the GPL. If the tool were used only internally, no distribution occurs and the obligation is not triggered. Had the code been MIT-licensed, the firm could ship binaries without releasing source, keeping only the copyright notice.
Traps that cost marks
- Equating free of charge with open source; freeware cannot be modified or redistributed.
- Assuming a licence can be transferred when it is OEM-bound.
- Confusing a compiler with an interpreter, or an API with an SDK.
- Forgetting that copyleft obligations trigger on distribution, not on internal use.