Is correct to have a different REST interfaces depending of the consumer?

Question

Let’s say we have a REST interface of the Account resource

Admin/Account/Get
[Authorize(Admin)]
public ActionResult Get(id)
{
    if(id > 0)
       return _userService.Get(id);
    else
       return _userService.GetAll();
}
public ActionResult Post(account)
{
    return _userService.Save(account);
}

This Rest interface was created first for the use of the Admin of the server. So at first is only a private api. What is better? To create a different interface for the same resource but for the public api (different consumer) like the following:

Account/Get
[Authorize]
public ActionResult  Get()
{
    return _userService.Get(user.Id);
}

Or to create the same interface for the same Resource like this

Account/Get
[Authorize(Admin, Users)]
public ActionResult  Get(id)
{
  if(admin){
     if(id > 0)
         return _userService.Get(id);
     else
         return _userService.GetAll();
   } else {
         return _userService.Get(user.Id);
   }
}
public ActionResult Post(account)
{
   if(admin)
       return _userService.Save(account);
   return null;
}

It is better to have the same interface for the same resource regardless the consumer. Or is better to have a different rest API if the consumer has different privileges? Why?

Answer 1

Generally speaking it is better to have fewer more general interfaces than a lot of specific ones as more specific interfaces are more fragile i.e. every little change in the consumer is likely to also change the specific interface. They are also harder to maintain on the server side since making a change means you now have to update more interfaces (not to mention keep older versions alive)

Try to generalize to a single interface or at least to groups/types of consumers