Rest Standard: Path parameters or Request parameters

Question

I am creating a new REST service.

What is the standard for passing parameters to REST services. From different REST implementations in Java, you can configure parameters as part of the path or as request parameters. For example,

Path parameters http://www.rest.services.com/item/b

Request parameters http://www.rest.services.com/get?item=b

Does anyone know what the advantages/disadvantages for each method of passing parameters. It seems that passing the parameters as part of the path seems to coincide better with the notion of the REST protocol. That is, a single location signifies a unique response, correct?

Answer 1

Paths tend to be cached, parameters tend to not be, as a general rule.

So...

GET /customers/bob

vs

GET /customers?name=bob

The first is more likely to be cached (assuming proper headers, etc.) whereas the latter is likely not to be cached.

Answer 2

The first variation is a little cleaner, and allows you to reserve the request parameters for things like sort order and page, as in

http://www.rest.services.com/items/b?sort=ascending;page=6

Answer 3

Your second example of "request parameters" is not correct because "get" is included as part of the path. GET is the request type, it should not be part of the path.

There are 4 main types of requests:

 GET
 PUT
 POST
 DELETE

GET requests should always be able to be completed without any information in the request body. Additionally, GET requests should be "safe", meaning that no significant data is modified by the request.

Besides the caching concern mentioned above, parameters in the URL path would tend to be required and/or expected because they are also part of your routing, whereas parameters passed in the query string are more variable and don't affect which part of your application the request is routed to. Although could potentially also pass a variable length set of parameters through the url:

GET somedomain.com/states/Virginia,California,Mississippi/

A good book to read as a primer on this topic is "Restful Web Services". Though I will warn you to be prepared to skim over some redundant information.

Answer 4

I think it depends. One URL for one resource. If you want to receive that resource in a slightly different way, give it a query string. But for a value that would deliver a different resource, put it in the path.

So in your example, the variable's value is directly related to the resource being returned. So it makes more sens in the path.