Web services - REST vs PHP JSON RPC

Question

I am working on a project where I am trying to expose the function of the software. Basically I have my backend set up and was thinking of seperating the frontend from the backend code using JSON msgs. I am a little bit confused as to what is the difference between a service and an API. I know API can be build on top on services. But I have these two models in mind -- to access profile X using json-rpc

http://xyz.com/?request={"jsonrpc":"2.0","id":1,"method":"getProfile","params":{"id":"X"}}

or should it be like this using REST -

http://api.xyz.com/X

Thank You

Answer 1

"Service" vs "API" is a pretty vague question. Often, the two terms are used interchangeably. "REST" vs "RPC" is a little easier to explain.

Usually with REST, a URL represents a specific resource such as a "user", an "account", etc.. Typically, you can create/retrieve/update/delete these resources by using the HTTP methods POST/GET/PUT/DELETE. To update the profile for user 1125 you might send the following:

POST /user/1125 HTTP/1.1
Host: wherever.com
Content-type: application/x-www-form-urlencoded

firstName=Davey&lastName=Jones&email=dj%40thebrineydeep.com

Anything you wanted to do with user 1125, you would send a request to the same URL. There are exceptions and variants of this idea, but that's the crux of it.

RPC services is more like just using a function library, which is bound to a specific URL. You might have a whole bunch of related functions all bound to the URL /services/json. Then if you wanted to change the profile for old Davey Jones, you would:

POST /services/json HTTP/1.1
Host: wherever.com
Content-type: application/json

{ "jsonrpc": "2.0",
  "id": 1,
  "method": "setProfile",
  "params": [ 1125,
    { "firstName": "Davey",
      "lastName": "Jones",
      "email": "[email protected]"
    }
  ]
}

I personally like JSON-RPC better because:

• I don't have to try and fit all of my function calls into some kind of resource-to-url mapping that might not make sense
• We don't try to overload the HTTP response codes to indicate API errors. Every request returns a 200 response (unless there is a server error) and you know from the response body whether you got an error or not. JSON-RPC is particularly good at being explicit about error conditions.

Sometimes REST is better because:

• Sometimes the resource-to-URL mapping fits really well
• It is more intuitive for third parties to understand
• It offers a simpler model for just retrieving easily-identified information

I don't think either one is any easier to code.

Edit I changed the REST example to use the more common form-encoded data instead of JSON. But of course you can specify any data format you like with REST. It isn't carved in stone.