emqx_extension_hook

The emqx_extension_hook extremly enhance the extensibility for EMQ X. It allow using an others programming language to mount the hooks intead of erlang.

Feature

• Support python and java.
• Support all hooks of emqx.
• Allows you to use the return value to extend emqx behavior.

We temporarily no plans to support other languages. Plaease open a issue if you have to use other programming languages.

Architecture

 EMQ X                                      Third-party Runtimes
+========================+                 +====================+
|    Extension           |                 |                    |
|   +----------------+   |     Hooks       |  Python scripts /  |
|   |    Drivers     | ------------------> |  Java Classes   /  |
|   +----------------+   |     (pipe)      |  Others ...        |
|                        |                 |                    |
+========================+                 +====================+

Drivers

Python

Requirements:

• It requires the emqx hosted machine has Python3 Runtimes (not support python2)
• The python3 executable commands in your shell

Examples:

See test/scripts/main.py

Java

Requirements:

• It requires the emqx hosted machine has Java 8+ Runtimes
• An executable commands in your shell, i,g: java

Examples:

See test/scripts/Main.java

Configurations

Name	Data Type	Options	Default	Description
drivers	Enum	python3 java	python3	Drivers type
.path	String	-	data/extension	The codes/library search path
.call_timeout	Duration	-	5s	Function call timeout
.pool_size	Integer	-	8	The pool size for the driver
.init_module	String	-	main	The module name for initial call

SDK

See sdk/README.md

Known Issues or TODOs

Configurable Log System

• use stderr to print logs to the emqx console instead of stdout. An alternative is to print the logs to a file.
• The Java driver can not redirect the stderr stream to erlang vm on Windows platform.

Reference

• erlport
• Eexternal Term Format
• The Ports Tutorial of Erlang