feat: add fhttp example command (#4)

* initial ASGI implementation

* Example HTTP usage 'fhttp' cmd

cmd/fhttp/README.md

@@ -0,0 +1,6 @@
+# Function HTTP Test Command
+
+fhttp is a command which illustrates how the func-python library
+wraps a function and exposes it as a service.  Useful for development.
+
+

cmd/fhttp/main.py

@@ -0,0 +1,71 @@
+import argparse
+import logging
+import func_python.http
+
+logging.basicConfig(level=logging.INFO)
+
+parser = argparse.ArgumentParser(description='Serve a Test Function')
+parser.add_argument('--static', action='store_true',
+                    help='Serve the example static handler (default is to '
+                         'instantiate and serve the example class)')
+args = parser.parse_args()
+
+
+async def handle(scope, receive, send):
+    """ handle is an example of a static handler which can be sent to the
+    middleware as a funciton.  It will be wrapped in a default Funciton
+    instance before being served as an ASGI application.
+    """
+    logging.info("OK: static")
+
+    await send({
+        'type': 'http.response.start',
+        'status': 200,
+        'headers': [[b'content-type', b'text/plain']],
+    })
+    await send({
+        'type': 'http.response.body',
+        'body': 'OK: static'.encode(),
+    })
+
+
+class Function:
+    """ Function is an example of a functioon instance.  The structure
+    implements the function which will be deployed as a network service.
+    The class name can be changed.  The only required method is "handle".
+    """
+
+    async def handle(self, scope, receive, send):
+        """ handle is the only method which must be implemented by the
+        function instance for it to be served as an ASGI handler.
+        """
+        logging.info("OK: instanced")
+
+        await send({
+            'type': 'http.response.start',
+            'status': 200,
+            'headers': [[b'content-type', b'text/plain']],
+        })
+        await send({
+            'type': 'http.response.body',
+            'body': 'OK: instanced'.encode(),
+        })
+
+
+def new():
+    """ new is the factory function (or constructor) which will create
+    a new function instance when invoked.  This must be named "new", and the
+    structure returned must include a method named "handle" which implements
+    the ASGI specification's method signature.  The name of the class itself
+    can be changed.
+    """
+    return Function()
+
+
+if __name__ == "__main__":
+    if args.static:
+        logging.info("Starting static handler")
+        func_python.http.serve(handle)
+    else:
+        logging.info("Starting new instance")
+        func_python.http.serve(new)