Use MQTTv5 and shared subscriptions

[jschlyter]

Summary by CodeRabbit

• New Features
  • Enhanced message subscriptions with an updated configuration to support shared messaging.
  • Improved communication settings by upgrading the protocol version for better MQTT connectivity.

[coderabbitai]

Walkthrough

The changes update the MQTT topic configuration and client connection settings. The configuration file (evrec.toml) now uses a shared subscription topic ("$share/evrec/events/up/#") instead of "events/up/#". In addition, the MQTT client within the server component (evrec/server.py) is now explicitly instantiated with aiomqtt.ProtocolVersion.V5, ensuring that the connection uses MQTT version 5.

Changes

File(s)	Change Summary
evrec.toml (configured via README)	Updated the topic_read parameter from "events/up/#" to "$share/evrec/events/up/#"
evrec/server.py	Modified the MQTT client instantiation to include protocol=aiomqtt.ProtocolVersion.V5

Sequence Diagram(s)

sequenceDiagram
    participant S as EvrecServer
    participant C as aiomqtt.Client (Protocol V5)
    participant B as MQTT Broker

    S->>C: Initialize client with Protocol V5
    S->>C: Connect to broker
    C->>B: MQTT CONNECT (Protocol V5)
    B-->>C: CONNACK
    S->>C: Subscribe to "$share/evrec/events/up/#"
    C->>B: SUBSCRIBE request
    B-->>C: SUBACK

Loading

Poem

I'm a hopping coder, a cheerful little bunny,
Leaping through code with carrots and funny,
Topics now share like friends in a row,
And MQTT speaks with a new v5 glow.
Coding adventures make my heart skip—a joyful, bouncy show!

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Review profile: CHILL
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📥 Commits

Reviewing files that changed from the base of the PR and between 1ea1c25 and 003a0f3.

📒 Files selected for processing (2)

• README.md (1 hunks)
• evrec/server.py (1 hunks)

🔇 Additional comments (2)

evrec/server.py (1)

51-51: LGTM! Verify aiomqtt library compatibility with MQTTv5.

The addition of protocol=aiomqtt.ProtocolVersion.V5 aligns with the PR objectives to use MQTTv5 for shared subscriptions.

Let's verify the aiomqtt library compatibility with MQTTv5:

✅ Verification successful

🌐 Web query:

What is the latest version of aiomqtt and does it support MQTTv5?

💡 Result:

The latest version of aiomqtt is v2.3.0 (released August 6, 2024)[1][10]. This version introduces breaking changes and includes updates like Python 3.12 compatibility and client-wide message queues[1][10].

Yes, aiomqtt fully supports MQTTv5 along with versions 3.1.1 and 3.1[5][10]. Key MQTTv5 features are accessible through:

• Protocol version specification during client initialization
• Support for MQTTv5 properties in publish/subscribe operations
• Enhanced error handling with reason codes[5][6]

The library wraps paho-mqtt while adding an async/await interface, maintaining compatibility with MQTTv5 brokers like EMQX and Mosquitto[3][5]. Developers can use MQTTv5 features such as session expiry intervals and user properties through aiomqtt's API[6][9].

Citations:

• 1: https://github.com/empicano/aiomqtt/releases
• 2: http://www.steves-internet-guide.com/python-mqtt-client-changes/
• 3: https://www.emqx.com/en/blog/introduction-to-mqtt-5
• 4: https://community.meraki.com/t5/Developers-APIs/Python-and-MQTT/m-p/129976
• 5: https://github.com/empicano/aiomqtt
• 6: https://mobidev.biz/blog/mqtt-5-protocol-features-iot-development
• 7: https://pypi.org/project/asyncio-mqtt/
• 8: https://github.com/empicano/aiomqtt/blob/main/CHANGELOG.md
• 9: https://www.rabbitmq.com/blog/2023/07/21/mqtt5
• 10: https://pypi.org/project/aiomqtt/

---

LGTM! Verified aiomqtt fully supports MQTTv5.
The latest version of aiomqtt (v2.3.0) supports MQTTv5, which confirms that the change setting protocol=aiomqtt.ProtocolVersion.V5 is valid and aligned with the PR objectives.

README.md (1)

15-15: LGTM! Verify shared subscription syntax.

The update to use $share/evrec/events/up/# enables shared subscriptions and aligns with the PR objectives.

Let's verify the shared subscription syntax:

✅ Verification successful

🌐 Web query:

What is the correct syntax for MQTT shared subscriptions?

💡 Result:

The correct syntax for MQTT shared subscriptions follows this format:
$share/{GroupID}/{TopicFilter}

Key Components

1. $share - Mandatory prefix indicating a shared subscription
2. {GroupID} - Unique identifier for subscriber group (no wildcards: +, #, or /)
3. {TopicFilter} - Standard MQTT topic pattern (may include + and # wildcards)

Implementation Examples

Broker/Platform	Syntax Example	Source
Standard MQTT 5	$share/group1/sensors/temperature	[1][3][8]
HiveMQ	$share/my-group/home/+/status	[3][8]
AWS IoT Core	$share/cars/data	[7]
EMQX	$share/groupA/alerts/#	[6][9]

Important Notes

• Case sensitivity: GroupIDs are treated as case-sensitive by most brokers[1][8]
• Protocol variations:
  • Solace SMF uses #share/ prefix instead of $share/[5]
  • EMQX supports legacy $queue/ prefix for MQTT 3 compatibility[9]
• Wildcard restrictions: GroupID cannot contain wildcards (+, #) or slashes (/)[1][5][8]

This standardized syntax enables load balancing across subscriber groups while maintaining compatibility with major MQTT brokers like HiveMQ, EMQX, and AWS IoT Core[3][6][7]. For MQTT 3 clients, check broker-specific documentation for legacy implementations[9].

Citations:

• 1: https://cedalo.com/blog/mqtt-shared-subscriptions-guide/
• 2: https://www.ibm.com/docs/pt/wip-mg/5.0.0?topic=applications-shared-subscriptions-in-mqtt
• 3: https://www.hivemq.com/blog/mqtt5-essentials-part7-shared-subscriptions/
• 4: https://marsbased.com/blog/2024/03/28/horizontally-scale-iot-backends-with-mqtt-shared-subscriptions
• 5: https://solace.community/discussion/3447/shared-subscription-syntax-for-mqtt
• 6: https://docs.emqx.com/en/emqx/latest/messaging/mqtt-shared-subscription.html
• 7: https://aws.amazon.com/tr/blogs/iot/how-to-get-started-with-the-new-shared-subscriptions-in-aws-iot-core/
• 8: https://docs.hivemq.com/hivemq/latest/user-guide/shared-subscriptions.html
• 9: https://www.emqx.com/en/blog/introduction-to-mqtt5-protocol-shared-subscription
• 10: https://thingsboard.io/docs/mqtt-broker/user-guide/shared-subscriptions/

---

LGTM! MQTT shared subscription syntax is correct.

The code snippet uses the format $share/evrec/events/up/#, which aligns with the correct shared subscription syntax of $share/{GroupID}/{TopicFilter}. The GroupID ("evrec") does not include any disallowed wildcards, and the TopicFilter ("events/up/#") is properly formatted.

✨ Finishing Touches

• 📝 Generate Docstrings (Beta)

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