The best resource identifiers don't just provide descriptions for people and machines, but are designed with simplicity, stability and manageability in mind, as explained by Tim Berners-Lee in Cool URIs don't change and by the W3C Team in Common HTTP Implementation Problems (sections 1 and 3):
- Short, mnemonic URIs will not break as easily when sent in emails and are in general easier to remember, e.g. when debugging your Semantic Web server.
- Once you set up a URI to identify a certain resource, it should remain this way as long as possible. Think about the next ten years. Maybe twenty. Keep implementation-specific bits and pieces such as .php and .asp out of your URIs, you may want to change technologies later.
- Issue your URIs in a way that you can manage. One good practice is to include the current year in the URI path, so that you can change the URI-schema each year without breaking older URIs. Keeping all 303 URIs on a dedicated subdomain, e.g. http://id.example.com/alice, eases later migration of the URI-handling subsystem.