fer

Overview ¶

Package fer provides a basic framework to run FairMQ-like processes. Clients create fer Devices that exchange data via fer message queue sockets.

A client device might look like so:

import "github.com/alice-go/fer"
import "github.com/alice-go/fer/config"
type myDevice struct {
    cfg  config.Device
    imsg chan fer.Msg
    omsg chan fer.Msg
}

A device needs to implement the fer.Device interface:

func (dev *myDevice) Run(ctl fer.Controller)   error { ... }

Optionnally, the following methods may be also implemented:

func (dev *myDevice) Configure(cfg config.Device) error { ... }
func (dev *myDevice) Init(ctl fer.Controller)  error { ... }
func (dev *myDevice) Pause(ctl fer.Controller) error { ... }
func (dev *myDevice) Reset(ctl fer.Controller) error { ... }

Typically, the Configure method is used to retrieve the configuration associated with the client's device. The Init method is used to retrieve the channels of input/output data messages. The Run method is an infinite for-loop, selecting on these input/output data messages. This infinite for-loop will also NEED to listen for the Controller.Done() channel to exit that for-loop.

e.g.:

func (dev *myDevice) Init(ctl fer.Controller) error {
    imsg, err := ctl.Chan("data-1", 0)
    omsg, err := ctl.Chan("data-2", 0)
    dev.imsg = imsg
    dev.omsg = omsg
    return nil
}

func (dev *myDevice) Run(ctl fer.Controller) error {
    for {
        select {
        case data := <-dev.imsg:
            dev.omsg <- bytes.Repeat(data, 2)
        case <-ctl.Done():
            return nil
        }
    }
}

Then, to create an executable:

package main

func main() {
    err := fer.Main(&myDevice{})
    if err != nil {
        log.Fatal(err)
    }
}

Build it as usual and run like so:

$> go build -o my-device
$> ./my-device --help
Usage of my-device:
  -control string
    	starts device in interactive/static mode (default "interactive")
  -id string
    	device ID
  -mq-config string
    	path to JSON file holding device configuration
  -transport string
    	transport mechanism to use (zeromq, nanomsg, go-chan, ...) (default "zeromq")
$> ./my-device --id my-id --mq-config ./path/to/config.json