knowledge service (#367)

* Write knowledge core elements to Cassandra

* Store service works, building management service

* kg-manager

trustgraph-flow/trustgraph/cores/knowledge.py

@@ -0,0 +1,104 @@
+
+from .. schema import KnowledgeResponse, Error
+from .. knowledge import hash
+from .. exceptions import RequestError
+from .. tables.knowledge import KnowledgeTableStore
+import base64
+
+import uuid
+
+class KnowledgeManager:
+
+    def __init__(
+            self, cassandra_host, cassandra_user, cassandra_password,
+            keyspace,
+    ):
+
+        self.table_store = KnowledgeTableStore(
+            cassandra_host, cassandra_user, cassandra_password, keyspace
+        )
+
+    async def delete_kg_core(self, request, respond):
+
+        print("Deleting core...", flush=True)
+
+        await self.table_store.delete_kg_core(
+            request.user, request.id
+        )
+
+        await respond(
+            KnowledgeResponse(
+                error = None,
+                ids = None,
+                eos = False,
+                triples = None,
+                graph_embeddings = None,
+            )
+        )
+
+    async def fetch_kg_core(self, request, respond):
+
+        print("Fetch core...", flush=True)
+
+        async def publish_triples(t):
+            await respond(
+                KnowledgeResponse(
+                    error = None,
+                    ids = None,
+                    eos = False,
+                    triples = t,
+                    graph_embeddings = None,
+                )
+            )
+
+        # Remove doc table row
+        await self.table_store.get_triples(
+            request.user,
+            request.id,
+            publish_triples,
+        )
+
+        async def publish_ge(g):
+            await respond(
+                KnowledgeResponse(
+                    error = None,
+                    ids = None,
+                    eos = False,
+                    triples = None,
+                    graph_embeddings = g,
+                )
+            )
+
+        # Remove doc table row
+        await self.table_store.get_graph_embeddings(
+            request.user,
+            request.id,
+            publish_ge,
+        )
+
+        print("Fetch complete", flush=True)
+
+        await respond(
+            KnowledgeResponse(
+                error = None,
+                ids = None,
+                eos = True,
+                triples = None,
+                graph_embeddings = None,
+            )
+        )
+
+    async def list_kg_cores(self, request, respond):
+
+        ids = await self.table_store.list_kg_cores(request.user)
+
+        await respond(
+            KnowledgeResponse(
+                error = None,
+                ids = ids,
+                eos = False,
+                triples = None,
+                graph_embeddings = None
+            )
+        )
+