Implement a gRPC Unary RPC Service - The Networker

                      TASK
                    

Implementation

Implement a gRPC-style unary RPC service. In unary RPC, the client sends exactly one request and receives exactly one response.

gRPC message format on the wire:
[compressed_flag: 1 byte][message_length: 4 bytes][protobuf_message]

Implement a simple KeyValue service:

Request:  {"type": "grpc_call", "msg_id": 1, "service": "KeyValue", "method": "Get", "request": {"key": "user:1"}}
Response: {"type": "grpc_call_ok", "in_reply_to": 1, "status": "OK", "response": {"key": "user:1", "value": "Alice", "found": true}}

Request:  {"type": "grpc_call", "msg_id": 2, "service": "KeyValue", "method": "Put", "request": {"key": "user:2", "value": "Bob"}}
Response: {"type": "grpc_call_ok", "in_reply_to": 2, "status": "OK", "response": {"written": true}}

Request:  {"type": "grpc_call", "msg_id": 3, "service": "KeyValue", "method": "Get", "request": {"key": "missing"}}
Response: {"type": "grpc_call_ok", "in_reply_to": 3, "status": "NOT_FOUND", "response": {"key": "missing", "found": false}}

Sample Test Cases

Put and Get a keyTimeout: 5000ms

Input

{"src":"c0","dest":"n1","body":{"type":"init","msg_id":1,"node_id":"n1","node_ids":["n1"]}}
{"src":"c1","dest":"n1","body":{"type":"grpc_call","msg_id":2,"service":"KeyValue","method":"Put","request":{"key":"k1","value":"v1"}}}
{"src":"c1","dest":"n1","body":{"type":"grpc_call","msg_id":3,"service":"KeyValue","method":"Get","request":{"key":"k1"}}}

Expected Output

{"src": "n1", "dest": "c0", "body": {"type": "init_ok", "in_reply_to": 1, "msg_id": 0}}
{"src": "n1", "dest": "c1", "body": {"type": "grpc_call_ok", "in_reply_to": 2, "status": "OK", "response": {"written": true}, "msg_id": 1}}
{"src": "n1", "dest": "c1", "body": {"type": "grpc_call_ok", "in_reply_to": 3, "status": "OK", "response": {"key": "k1", "value": "v1", "found": true}, "msg_id": 2}}

Get missing key returns NOT_FOUNDTimeout: 5000ms

Input

{"src":"c0","dest":"n1","body":{"type":"init","msg_id":1,"node_id":"n1","node_ids":["n1"]}}
{"src":"c1","dest":"n1","body":{"type":"grpc_call","msg_id":2,"service":"KeyValue","method":"Get","request":{"key":"missing"}}}

Expected Output

{"src": "n1", "dest": "c0", "body": {"type": "init_ok", "in_reply_to": 1, "msg_id": 0}}
{"src": "n1", "dest": "c1", "body": {"type": "grpc_call_ok", "in_reply_to": 2, "status": "NOT_FOUND", "response": {"key": "missing", "found": false}, "msg_id": 1}}

Hints

Hint 1▾

Unary RPC: client sends one request, server sends one response

Hint 2▾

gRPC uses HTTP/2 as its transport protocol

Hint 3▾

Each RPC method maps to a (service, method) pair

Hint 4▾

The request and response are protobuf-encoded messages

Hint 5▾

gRPC adds a 5-byte header: 1 byte compressed flag + 4 bytes message length

Resources

gRPC Core Concepts

Overview of gRPC service definitions, RPC types, and lifecycle

                      OVERVIEW
                    

Theoretical Hub

Concept overview coming soon

Key Concepts

gRPCunary RPCHTTP/2service definitionstub

main.py

python