cerk_port_mqtt

cerk_port_mqtt

⚠️ this port currently supports the "Best Effort" delivery guarantee for incomming events:

The reason for this limitation is that the current version of the paho.mqtt.rust library acknowledges a received PUBLISH message automatically before the content of the message is handed over to the application.

If a "At Least Once" delivery guarantee for incommming messages is required, the cerk_port_mqtt_mosquitto must be used.

This is a package for CERK. CERK is an open source CloudEvents Router written in Rust with a MicroKernel architecture.

Introduction

CERK lets you route your CloudEvents between different different ports. Ports are transport layer bindings over which CloudEvents can be exchanged. It is built with modularity and portability in mind.

Components

CERK comes with a couple of prefabricated components, but implementing custom components is easy.

A good overview is provided on GitHub.

This Component: MQTT Port

This port publishes and/or subscribe CloudEvents to/from an MQTT v3.1 topic.

The port is implemented with a Eclipse Paho MQTT Rust Client and sends and receives messages according to the MQTT Protocol Binding for CloudEvents v1.0 specification

Configurations

The configurations should be of type cerk::kernel::Config::HashMap and have at least the entires:

Required Fields

host

The value has to by of type Config::String and contain a host name with protocol and port.

E.g. Config::String(String::from("tcp://mqtt-broker:1883"))

Optional Fields

send_topic

The value has to by of type Config::String and contain the MQTT topic name where the message will be sent to.

E.g. Config::String(String::from("test"))

The following configurations are optional.

subscribe_topic

The value has to by of type Config::String and contain the MQTT topic name which the router should subscribe to.

Configuration Examples

Configuration for sending and receiving events

use std::collections::HashMap;
use cerk::kernel::Config;

let map: HashMap<String, Config> = [
    ("host".to_string(), Config::String("tcp://mqtt-broker:1883".to_string())),
    ("subscribe_topic".to_string(), Config::String("inbox".to_string())),
    ("send_topic".to_string(), Config::String("outbox".to_string())),
]
.iter()
.cloned()
.collect();

let config = Config::HashMap(map);

Configuration for sending events

use std::collections::HashMap;
use cerk::kernel::Config;

let map: HashMap<String, Config> = [
    ("host".to_string(), Config::String("tcp://mqtt-broker:1883".to_string())),
    ("send_topic".to_string(), Config::String("outbox".to_string())),
]
.iter()
.cloned()
.collect();

let config = Config::HashMap(map);

Configuration for receiving events

use std::collections::HashMap;
use cerk::kernel::Config;

let map: HashMap<String, Config> = [
    ("host".to_string(), Config::String("tcp://mqtt-broker:1883".to_string())),
    ("subscribe_topic".to_string(), Config::String("inbox".to_string())),
]
.iter()
.cloned()
.collect();

let config = Config::HashMap(map);

Examples

• Generator to MQTT

Update Readme

The original readme text is a Rust doc comment in the lib.rs file

1. cargo install cargo-readme
2. cargo readme > README.md

License

Apache-2.0