IMHO the best way is to separate every request into single service methods that way you can reuse just a part of it and not make server calls to load to whole data, check the angular-resource $resource to have a clean reusable service of server calls and not a bunch of $https arround your code:
example:
A service that points some url of your backend server
.factory('ClientService', ['$resource', function($resource){
return $resource('http://some_url/:controller/:method', null, {
"agents": { method: 'GET', params: { controller: 'agent', method: 'search' }, cache: false },
"query": { method: 'GET', params: { controller: 'client', method: 'search' }, cache: false },
"save": { method: 'POST', params: { controller: 'client', method: 'save' } },
"delete": { method: 'POST', params: { controller: 'client', method: 'delete' } }
})
}])
The use in the controller (Injecting ClientService as dependency)
// If i want to query the agents into a scope element
// that will call the url = http://some_url/agent/search
$scope.agents = ClientService.agents();
// If i want to query a single client i cant send adtional params
// as is a get request it will call http://some_url/client/search?id=5
$scope.client = ClientService.query({id:5});
// and you can event manage callbacks if you want to
// This will send the client object to the url = http://some_url/client/save
ClientService.save($scope.client).$promise.then(function(response){ alert(response) })
As you can see this way you can access just the things you need from the backend server not having to do all the callback response if you dont need to and in a reusable cleaner way
Info Angular Resource Docs
