RESTful API设计：内部交互

Question

Simple question. I read a bunch of articles about API design and didn't find the answer.

How should API's endpoints interact with each other?

For example, if I have 2 endpoints: /category/:name and /messages . What is the best way for example to check category existence from messages?

1) Database query from /messages handler like: SELECT * FROM categories WHERE name = 'test'?

or

2) HTTP request from /messages handler to that endpoint like: httpclient.get('/category/test') ?

or

3) Client should get all categories, get ID of particular category and send request to /messages with that category ID?

Answer 1

The question is simple but not an answer. One thing is sure, never use (2) solution. Requesting some data using http client when you can invoke a method will decrease performance and capacity of your API.

If checking existence of a particular category is required to create response in /messages then use (1) but instead of invoking SQL query invoke the same method as used to handle request to /category/test just invoke it locally not through HTTP.

Solution (3) is the REST-way when each endpoint is responsible only for one type of resources. The disadvantage is that it may require more HTTP requests from client to API.

Answer 2

You should design your application in a way that all the endpoint are calling internal APIs for performing the task. When you want to invoke one operation inside other then you should use the respective internal API instead of any other approach like calling http service.