SPIKE Task

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Enhance skills on daily basis will be noted here

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Follow this article - https://blog.logrocket.com/building-typescript-cli-node-js-commander/ to create a cli to create a new tool (mqtt-client)

• #! /usr/bin/env node shebang line which tells the OS to run the file with the node interpreter.

Question:

1. What is read-eval-print loop (REPL)? >> solved
2. How to input the args to the "scripts" in package.json file then pass it to the tool?
   --- Alternative: use "bin" in package.json instead

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https://www.hivemq.com/blog/mqtt-essentials-part2-publish-subscribe/ pub/sub concept:

• Store message in broker should meet 2 conditions: the client had connected with a persistent session and subscribed to a topic with a QoS greater than 0

https://www.hivemq.com/blog/mqtt-essentials-part-7-persistent-session-queuing-messages/ session and queue messages

• cleanSession flag

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https://www.hivemq.com/blog/mqtt-essentials-part-8-retained-messages/ Retained messsage

• Retained message flag
• Send retained message by setting flag when pub it to broker
• Delete retained message by sending zero-byte payload

Use case: A retained message makes sense when you want newly-connected subscribers to receive messages immediately (without waiting until a publishing client sends the next message) >> use for update status

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https://www.hivemq.com/blog/mqtt-essentials-part-9-last-will-and-testament/ LWT

Best practices: LWT is a great way to notify other subscribed clients about the unexpected loss of connection of another client

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ACL