architecture sandbox

• proposes 4 evolutive exercises with solution
• explores class inheritance & delegation, function wrappers and decorators

EXO 1:

mock of python requests and xmlrpc librairies

• RestRequest class to mock requests library
  usage:
  

    implements class methods get, post, put, delete
    response = RestRequest.<method>(auth, data, name, url)

• RpcRequest class to mock xmlrpc library
  usage:
  

    implements specific rpc methods ListAll, Create, ... depending on instance
    rpc_client = RpcRequest(name, url)
    response = rpc_client.<method>(auth, data)

• Both RestRequest and RpcRequest methods return a generic mock function "all_method" that represents the http request:

def all_method(method, auth, data, name, url):
    """emulate a rest or rpc request on url"""
    if auth == AUTHORIZATION_CODE:
        return f"authorized {method} request of {data} on {name} {url}"
    else:
        return f"!! UNAUTHORIZED !!, auth = {auth} on {name} {url}"

• exo1 automates the creation of RestRequest and RpcRequest methods based on specific wrappers of all_methods

EXO 2:

Implements a generic RestClient for HTTP REST requests using the mock RestRequest created in exo1
The generic rest client architecture is as follow:

• api specific daughter classes
  • one implemented as Contentd
  • exposes api rest functions for each api endpoint
  • the @api_request decorator automates the exposition so that the endpoint function does not need any specific code. Only a docstring:

    @api_request(rest_method, this_endpoint_path/{args})
    def this_endpoint_path_function(self, args=args, data=data):
        """doc string"""
        !! no code !! 

• generic parent class RestClient

  • implementing a _do_operation method to make the rest request on the api url
  • _do_operation is called by the @api_rest decorator of each endpoint_function

• exo2 explores the construction of the @api_rest decorator and the _do_operation generic function

EXO 3

Implements a generic RpcClient for XML RPC requests with the mock RpcRequest created in exo1.
The rpc client architecture is as follow:

• api specific daughter class
  • one implemented as Onevsh
  • exposes custom functions for specific rpc endpoints
• generic parent class RpcClient
  • creates the needed client xmlrpc instances, for example:

  self.onev = RpcRequest('onev', onev_url)
  

  • class delegation of the daughter classes methods call to these instances
  • the delegation is implemented in a _do_rpc_operation method
• exo3 explores the construction of the _do_rpc_operation method and how to fill in the auth parameter

EXO 4

Full sandbox with both rest and rpc clients. The auth parameter is passed as default at init of the rest Contentd(RestClient) and rpc Onevsh(RpcClient) classes.
Here we look at how the default auth can be bypassed by redefining the _do_rpc_operation and _do_operation of the parent class in Onevsh and Contentd daughter classes.
A new class Libcdn inherits from both rest and rpc clients to propose advanced functions (so called macros). The macros may be exposed by a Flask app with specific user authentication. hence the need to redefine the auth credentials in the Flask context, depending on the user credentials accessing the maco endpoint.