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/dispatch/graph_rag.py

@@ -0,0 +1,36 @@
+
+from ... schema import GraphRagQuery, GraphRagResponse
+
+from . requestor import ServiceRequestor
+
+class GraphRagRequestor(ServiceRequestor):
+    def __init__(
+            self, pulsar_client, request_queue, response_queue, timeout,
+            consumer, subscriber,
+    ):
+
+        super(GraphRagRequestor, self).__init__(
+            pulsar_client=pulsar_client,
+            request_queue=request_queue,
+            response_queue=response_queue,
+            request_schema=GraphRagQuery,
+            response_schema=GraphRagResponse,
+            subscription = subscriber,
+            consumer_name = consumer,
+            timeout=timeout,
+        )
+
+    def to_request(self, body):
+        return GraphRagQuery(
+            query=body["query"],
+            user=body.get("user", "trustgraph"),
+            collection=body.get("collection", "default"),
+            entity_limit=int(body.get("entity-limit", 50)),
+            triple_limit=int(body.get("triple-limit", 30)),
+            max_subgraph_size=int(body.get("max-subgraph-size", 1000)),
+            max_path_length=int(body.get("max-path-length", 2)),
+        )
+
+    def from_response(self, message):
+        return { "response": message.response }, True
+