README
¶
Ethernet Frames Message Queue (EFMQ)
EFMQ provides an MQTT pub/sub style abstraction for Ethernet Frame messaging.
EFMQ is like MQTT for your Local Area Network. Unlike MQTT no remote or local broker is required, message traffic is effectively broadcast peer-to-peer. With EFMQ, messages never leave your network.
Messaging can be two-way. Each node can operate as either a publisher or subscriber, or both.
This package leans heavily on @mdlayher's raw and ethernet packages, which do almost all the heavy lifting.
Usage
Basic publisher and subscriber examples are provided below. Nodes can publish and subscribe to multiple topics.
The API follows a typical MQTT client API loosely.
// Create connection
mq, _ := efmq.NewEFMQ(networkInterface string)
// Publish
mq.Publish(topic string, payload string)
// Subscribe
mq.Subscribe(topic string)
// Unsubscribe
mq.Unsubscribe(topic string)
// List subscriptions
mq.Subscriptions()
// Start listening
mq.Listen()
// Message channel
mq.Message
// Message
Message struct {
Topic string
Payload string
}
Publisher example
The code below will publish data to the fermenter topic every second. en1 is the network interface on Mac (my Mac at least). On a Raspberry Pi it might be wlan0. Use netstat -i to discover.
mq, err := efmq.NewEFMQ("en1")
if err != nil {
log.Fatal(err)
}
t := time.NewTicker(1 * time.Second)
for range t.C {
if err := mq.Publish("fermenter", "20.5"); err != nil {
log.Fatalln(err)
}
}
Subscriber example
The code below sets up a subcription to the fermenter topic and then listens for messages. Messages are received on a channel.
mq, err := efmq.NewEFMQ("wlan0")
if err != nil {
log.Fatal(err)
}
mq.Subscribe("fermenter")
mq.Listen()
for msg := range mq.Message {
fmt.Println("topic:", msg.Topic)
fmt.Println("message:", msg.Payload)
}
Todo
- Better test coverage
- Check message does not exceed frame byte data limit (1500 bytes?)
Documentation
¶
Overview ¶
Package efmq provides basic MQTT like functionality for message publishing and subscriptions within a local area network
Example (Publisher) ¶
This example starts publishing to a topic every second via the network interface "wlan0".
package main
import (
"log"
"time"
"github.com/olliephillips/efmq"
)
func main() {
mq, err := efmq.NewEFMQ("wlan0")
if err != nil {
log.Fatal(err)
}
t := time.NewTicker(1 * time.Second)
for range t.C {
if err := mq.Publish("fermenter", "20.5"); err != nil {
log.Fatalln(err)
}
}
}
Output:
Example (Subscriber) ¶
This example sets up a subscription to a topic and starts listening for messages from a device on the same network.
package main
import (
"fmt"
"log"
"github.com/olliephillips/efmq"
)
func main() {
mq, err := efmq.NewEFMQ("wlan0")
if err != nil {
log.Fatal(err)
}
mq.Subscribe("fermenter")
mq.Listen()
for msg := range mq.Message {
fmt.Println("topic:", msg.Topic)
fmt.Println("message:", msg.Payload)
}
}
Output: fermenter 20.5 fermenter 20.5 fermenter 20.5
Index ¶
Examples ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type EFMQ ¶
type EFMQ struct {
Message chan Message
// contains filtered or unexported fields
}
EFQM represents a connection
func (*EFMQ) Listen ¶
func (mq *EFMQ) Listen()
Listen announces the subscriptions to which we are subscribed and then starts listener func in goroutine
func (*EFMQ) Publish ¶
Publish broadcasts a message on the network which comprises topic and payload
func (*EFMQ) Subscriptions ¶
Subscriptions returns list of topics currently subscribed to
func (*EFMQ) Unsubscribe ¶
Unsubscribe removes subscription from slice store
Source Files