HOW TO IMPROVE ON

MQTT 3.1.1Tim Kellogg

@kellogh

MQTT: An Implementor’s Perspective

AOL Keywords: vasters mqtt

MQTT

Servers

Wired Networks

Vertically scaled

Kafka | AMQP | HTTP

loca-tion

tempfuel

Funnel Protocol

MQTT

“Uptime” isn’t straightforward

“Exactly Once” Violates CAP

Security Problems

• Retained messages

• Provenance

Error Handling

CAP Theorem

Availability

Network Partitions

Consistency CP

AP

CAP Theorem

Availability

Partition Tolerance

Guaranteed In-Order Delivery

CP

AP

Subscriber dies prematurely

Receive

• Via QoS 2

Do Work

• Not idempotent work

• Duplicate message would cause errors

Crash

• ACK isn’t sent

Subscriber dies prematurely (2)

Receive

• Via QoS 2

ACK

• Auto-acknowledge

Crash

• Before work is done

MQTT Recommendations

Message Dedup

• Have clients implement “QoS 2” via QoS 1

Token-based Security

Provenance story

Metadata about messages

Error codes

CoAP-PubSub

Resource Directory

Garbage Collection

Polling Allowed

Retained Messages

Error Codes

QUESTIONS?@kellogh

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