VerneMQ
  • Welcome
  • Getting Started
  • MQTT Introduction
  • Installing VerneMQ
    • Running VerneMQ using Docker
  • Configuring VerneMQ
    • Introduction
    • The VerneMQ conf file
    • Auth using files
    • Auth using a database
    • Enhanced Auth
    • MQTT Options
    • MQTT Listeners
    • HTTP Listeners
    • Non-standard MQTT options
    • Websockets
    • Logging
    • Consumer session balancing
    • Plugins
    • Shared subscriptions
    • Advanced Options
    • Storage
    • No Op Engine
    • Generic offline store
    • Redis based message passing
    • Redis based subscription store
    • MQTT Bridge
  • VerneMQ Clustering
    • Introduction
    • Inter-node Communication
    • Dealing with Netsplits
  • Live Administration
    • Introduction
    • Inspecting and managing sessions
    • Retained messages
    • Live reconfiguration
    • Managing Listeners
    • HTTP API
    • Tracing
  • Monitoring
    • Introduction
    • $SYSTree
    • Graphite
    • Netdata
    • Prometheus
    • Health Checker
    • Status Page
  • Plugin Development
    • Introduction
    • Session lifecycle
    • Subscribe Flow
    • Publish Flow
    • Enhanced Auth Flow
    • Erlang Boilerplate
    • Lua Scripting Support
    • Webhooks
    • Events sidecar Plugin
  • Misc
    • Loadtesting VerneMQ
    • Not a tuning guide
    • Change Open File Limits
  • Guides
    • A typical VerneMQ deployment
    • VerneMQ on Kubernetes
    • Loadtesting VerneMQ
    • Clustering during development
    • Not a tuning guide
    • Change Open File Limits
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  • auth_on_subscribe and auth_on_subscribe_m5
  • on_subscribe and on_subscribe_m5
  • on_unsubscribe and on_unsubscribe_m5
  1. Plugin Development

Subscribe Flow

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Last updated 2 years ago

In this section the subscription flow is described. VerneMQ provides several hooks to intercept the subscription flow. The most important ones are the auth_on_subscribe and auth_on_subscribe_m5 hooks which act as an application level firewall granting or rejecting subscribe requests.

auth_on_subscribe and auth_on_subscribe_m5

The auth_on_subscribe and auth_on_subscribe_m5 hooks allow your plugin to grant or reject subscribe requests sent by a client. They also makes it possible to rewrite the subscribe topic and qos. The auth_on_subscribe hook is specified in the Erlang behaviour auth_on_subscribe_hook and the auth_on_subscribe hook in the auth_on_subscribe_m5_hook behaviour available in the vernemq_dev repo.

on_subscribe and on_subscribe_m5

The on_subscribe and on_subscribe_m5 hooks allow your plugin to get informed about an authorized subscribe request. The on_subscribe hook is specified in the Erlang behaviour on_subscribe_hook and the on_subscribe_m5 hook in the on_subscribe_m5_hook behaviour available in the vernemq_dev repo.

on_unsubscribe and on_unsubscribe_m5

The on_unsubscribe and on_unsubscribe_m5 hooks allow your plugin to get informed about an unsubscribe request. They also allow you to rewrite the unsubscribe topic if required. The on_subscribe hook is specified in the Erlang behaviour on_unsubscribe_hook and the on_unsubscribe_m5 hook in the on_unsubscribe_m5_hook behaviour available in the vernemq_dev repo.