I have created a quite simple RESTful web service. It only supports the GET (=read) method, e.g.:
http://localhost/application/id/xyz
The corresponding information for this ID is queried from a data source and returned as JSON. Now my question: (How) should I implement HATEOAS in this case? Does it even make sense? I understand that HATEOAS is reasonable when having a more complex structure. But in this case, there are no other resources I could link to. The client calls the web service with a certain ID and the server returns information.
Thank you!
As you've said "The client calls the web service with a certain ID" it sounds like you've written your client to visit a specific URL in your service which has the URL to visit generated by the client, i.e. your client application already knows it can visit http://localhost/application/id/xyz for the xyz ID.
If you'd like to leverage some of the power of HATEOAS and decouple yourself from this (slight) dependency, you could instead be querying http://localhost/application/id?query=xyz which could return a list of valid links (if any exist). That way you could change the format or structure of the linked URL without issues for your client (of course, you'd still be dependent on the query URL in some way).
However, as your usage is so simple, this sounds like overkill and unnecessary work so I'd suggest you don't need to worry about HATEOAS until you have a more complex system or clients :)