What's a RESTful url for a linked item?

Question

This is going to be a web service that returns a JSON object. Currently, I'm using C# technology and simply using ASP.Net MVC to create the calls. This is not a web page, so SEO is not a concern.

I've come across a number of instances where I want to get the "next" or "previous" item in a list. For example, I've got a service that returns a featured photo. http://myservice.com/photos/123 which returns a JSON

{"name": "At_The_Concert", "id": "123", "src": "http://myservice.com/photostore/123.jpg"}

The client (Ajax, Mobile device, etc.) of this service wants to know what the “next” item is going to be. I’m struggling about what the url should be.

• http://myservice.com/photos/123/next
• http://myservice.com/photos/next/123
• http://myservice.com/nextphotos/123

or maybe the id property should just be a parameter

http://myservice.com/photos/next?photoId=123

Or maybe this is entirely wrong and it should be like

http://myservice.com/photos/?method=getNextPhoto&photoId=123

though with .Net's routing, it might be easier to write it as http://myservice.com/photos/method/getNextPhoto?photoId=123

I’m relatively new to web services and REST. I get the basic CRUD for REST, but I don’t know what is the best practice for creating more custom urls, in this case the “next” photo. Is there an accepted RESTful practice?

Answer 1

Do it this way:

{"name": "At_The_Concert", "id": "123", "src": "http://myservice.com/photostore/123.jpg",
"next": "http://myservice.com/photos/345/",
"prev": "http://myservice.com/photos/901/"}

Answer 2

Having the next function be an operation server-side requires state information, particularly if you are involving filtering. This violates REST.

It seems more appropriate to provide a directory list at http://myservice.com/photos, and let the app call the appropriate http://myserivce.com/photos/id link when hitting next/previous. With this method, the filtering logic would be on the client, and it could be modified/reset without having to call the service again.

Alternatively, you could have request parameters into the http://myservice.com/photos that returns a filtered list. Naturally, this would require additional service calls if the filter changed, so you may wish to stick with the former suggestion.

The end result would be the same, however. Your state would reside where it should - in the client app as opposed to the server.

Answer 3

Another option is to look at OData and Service Operations it will guarantee RESTful style of your calls.