Chapters

Application Protocols Module Guide

Bex, your messaging guide

Your guide: Bex

“A message with no listener is a tree falling in an empty forest — plan where it goes and what it says.”

Start With the Module

This section: Start With the Module — This guide maps the current learning path for App Protocols.

This guide maps the current learning path for App Protocols. The module contains 16 chapters, linked below in the order learners can study them.

Compare two message paths for the same soil reading and two different team needs.

  1. Broker Bex stands beside one soil sensor while two teams consider different ways to receive its readings.

    One soil sensor serves two teams.

  2. One reading moves from the soil sensor to a nearby gateway, an acknowledgement returns, and the sensor sleeps.

    The first team needs one daily reading.

  3. One publication enters a central broker and branches to a dashboard, rule check, and maintenance app.

    The second team needs every update in three places.

  4. Broker Bex compares a direct acknowledged sensor exchange with one brokered publication reaching three subscribers.

    The message path should fit each team's need.

The same reading follows either a quiet direct exchange or a brokered fan-out path.

An application protocol is a shared set of rules for exchanging messages. This module introduces the main choices before asking you to compare them:

  • HTTP means Hypertext Transfer Protocol. It carries web requests and responses. REST is a common way to organise resources and actions over HTTP.
  • MQTT means Message Queuing Telemetry Transport. Telemetry means measurements or status reports sent from a device. A payload is the useful data inside a message.
  • CoAP means Constrained Application Protocol. It gives small devices a request-and-response style similar to the web. It commonly runs over UDP, which means User Datagram Protocol.
  • AMQP means Advanced Message Queuing Protocol. A broker is a service that receives messages and sends them to the right consumers.
  • A gateway is a device or service that links one network or message system to another.

With that word now introduced, the guide’s full nickname is Broker Bex.

Chapters by Part

This section: Chapters by Part

Protocol Overview & Selection

HTTP & Web Protocols

Protocol Debate Scenarios

Choose a Starting Point

This section: Choose a Starting Point — If this subject is new, follow the parts and chapters in the order shown above.

If this subject is new, follow the parts and chapters in the order shown above. If you already have a specific design or troubleshooting question, use the relevant part heading and open the direct chapter link whose title matches that question.

Use the sidebar and site search for supporting material; use this chapter map as your main route through the module.

The Dedicated Messaging Books

This section: The Dedicated Messaging Books — This overview module covers protocol selection and the HTTP/web family.

This overview module covers protocol selection and the HTTP/web family. For the three dedicated messaging books, use the current canonical entry chapters:

How to Use This Material

This section: How to Use This Material

  • Start with the first chapter in the relevant part when the topic is unfamiliar.
  • Use direct chapter links for study plans, lab preparation, and review evidence.

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