We are building a software system that maintains a collection of participating entities, and I'm trying to determine if it is more appropriately termed a registry or a directory.
From various dictionary definitions it is not easy to distinguish between the two. From current usage I would say it is as follows:
- A registry is an official record keeping institution, such as the UK Land Registry. Ownership of all land in the UK is registered there. Unless you are in there, it might be hard/impossible to prove that you own a piece of land.
- A directory is a collection, which does not need to be either official or comprehensive, such as the telephone directory. You can happily make and receive phone calls, whether you are in the directory or not.
If the participating entities enter the collection voluntarily, and can operate without doing so, I would suggest you use directory; a registry would require them to be part of it.
However, despite its name, use of the Windows Registry is not mandatory for applications.