Flow API - update gateway (#357)

* Altered API to incorporate Flow IDs, refactored for dynamic start/stop of flows
* Gateway: Split endpoint / dispatcher for maintainability

trustgraph-flow/trustgraph/gateway/endpoint/variable_endpoint.py

@@ -0,0 +1,67 @@
+
+import asyncio
+from aiohttp import web
+import uuid
+import logging
+
+logger = logging.getLogger("endpoint")
+logger.setLevel(logging.INFO)
+
+class VariableEndpoint:
+
+    def __init__(self, endpoint_path, auth, dispatcher):
+
+        self.path = endpoint_path
+
+        self.auth = auth
+        self.operation = "service"
+
+        self.dispatcher = dispatcher
+
+    async def start(self):
+        pass
+
+    def add_routes(self, app):
+
+        app.add_routes([
+            web.post(self.path, self.handle),
+        ])
+
+    async def handle(self, request):
+
+        print(request.path, "...")
+
+        try:
+            ht = request.headers["Authorization"]
+            tokens = ht.split(" ", 2)
+            if tokens[0] != "Bearer":
+                return web.HTTPUnauthorized()
+            token = tokens[1]
+        except:
+            token = ""
+
+        if not self.auth.permitted(token, self.operation):
+            return web.HTTPUnauthorized()
+
+        try:
+
+            data = await request.json()
+
+            print(data)
+
+            async def responder(x, fin):
+                print(x)
+
+            resp = await self.dispatcher.process(
+                data, responder, request.match_info
+            )
+
+            return web.json_response(resp)
+
+        except Exception as e:
+            logging.error(f"Exception: {e}")
+
+            return web.json_response(
+                { "error": str(e) }
+            )
+