Implement Protocol Versioning with Backward Compatibility - The Networker

                      TASK
                    

Implementation

Implement a protocol versioning scheme. The sender includes a protocol_version in the header. The receiver handles backward compatibility for older versions.

Protocol versions:

v1: {version: 1, key: string, value: string}
v2: {version: 2, key: string, value: string|int, timestamp_ms: number, tags: string[]}

When receiving a v1 message, upgrade it to v2 with defaults: timestamp_ms = 0, tags = [].

Implement handlers:

Request:  {"type": "proto_send_v1", "msg_id": 1, "key": "name", "value": "Alice"}
Response: {"type": "proto_send_v1_ok", "in_reply_to": 1, "wire_version": 1}

Request:  {"type": "proto_send_v2", "msg_id": 2, "key": "age", "value": 30, "timestamp_ms": 1700000000, "tags": ["user"]}
Response: {"type": "proto_send_v2_ok", "in_reply_to": 2, "wire_version": 2}

Request:  {"type": "proto_receive", "msg_id": 3, "wire_version": 1, "key": "name", "value": "Alice"}
Response: {"type": "proto_receive_ok", "in_reply_to": 3, "parsed_version": 2, "key": "name", "value": "Alice", "timestamp_ms": 0, "tags": []}

Sample Test Cases

Send v1 messageTimeout: 5000ms

Input

{"src":"c0","dest":"n1","body":{"type":"init","msg_id":1,"node_id":"n1","node_ids":["n1"]}}
{"src":"c1","dest":"n1","body":{"type":"proto_send_v1","msg_id":2,"key":"name","value":"Alice"}}

Expected Output

{"src": "n1", "dest": "c0", "body": {"type": "init_ok", "in_reply_to": 1, "msg_id": 0}}
{"src": "n1", "dest": "c1", "body": {"type": "proto_send_v1_ok", "in_reply_to": 2, "wire_version": 1, "msg_id": 1}}

Receive v1 message upgraded to v2Timeout: 5000ms

Input

{"src":"c0","dest":"n1","body":{"type":"init","msg_id":1,"node_id":"n1","node_ids":["n1"]}}
{"src":"c1","dest":"n1","body":{"type":"proto_receive","msg_id":2,"wire_version":1,"key":"name","value":"Alice"}}

Expected Output

{"src": "n1", "dest": "c0", "body": {"type": "init_ok", "in_reply_to": 1, "msg_id": 0}}
{"src": "n1", "dest": "c1", "body": {"type": "proto_receive_ok", "in_reply_to": 2, "parsed_version": 2, "key": "name", "value": "Alice", "timestamp_ms": 0, "tags": [], "msg_id": 1}}

Hints

Hint 1▾

Include a protocol_version field in the message header

Hint 2▾

Version 1: basic key-value with string values only

Hint 3▾

Version 2: adds integer values and a timestamp field

Hint 4▾

The receiver must handle both v1 and v2 messages

Hint 5▾

Use sensible defaults for missing fields when upgrading v1 to v2

Resources

Protocol Buffers - Language Guide (proto3)

How Protocol Buffers handle schema evolution and backward compatibility

                      OVERVIEW
                    

Theoretical Hub

Concept overview coming soon

Key Concepts

protocol versioningbackward compatibilitywire formatmigration

main.py

python