Awesome
Betwixt - A LWM2M Client and Server in Go
Betwixt is a Lightweight M2M implementation written in Go
OMA Lightweight M2M is a protocol from the Open Mobile Alliance for M2M or IoT device management. Lightweight M2M enabler defines the application layer communication protocol between a LWM2M Server and a LWM2M Client, which is located in a LWM2M Device.
The OMA Lightweight M2M enabler includes device management and service enablement for LWM2M Devices. The target LWM2M Devices for this enabler are mainly resource constrained devices. Therefore, this enabler makes use of a light and compact protocol as well as an efficient resource data model. It provides a choice for the M2M Service Provider to deploy a M2M system to provide service to the M2M User.
Basic Client Example
package main
import (
"github.com/zubairhamed/betwixt"
"github.com/zubairhamed/betwixt/examples"
"github.com/zubairhamed/betwixt/examples/objects"
)
func main() {
cli := examples.StandardCommandLineFlags()
registry := betwixt.NewDefaultObjectRegistry()
c := betwixt.NewLwm2mClient("TestClient", ":0", cli.Server, registry)
setupResources(c, registry)
c.OnStartup(func() {
c.Register(cli.Name)
})
c.Start()
}
func setupResources(client betwixt.LWM2MClient, reg betwixt.Registry) {
client.SetEnabler(betwixt.OMA_OBJECT_LWM2M_SECURITY, objects.NewExampleSecurityObject(reg))
client.AddObjectInstances(betwixt.OMA_OBJECT_LWM2M_SECURITY, 0, 1, 2)
client.SetEnabler(betwixt.OMA_OBJECT_LWM2M_SERVER, objects.NewExampleServerObject(reg))
client.AddObjectInstance(betwixt.OMA_OBJECT_LWM2M_SERVER, 1)
client.SetEnabler(betwixt.OMA_OBJECT_LWM2M_DEVICE, objects.NewExampleDeviceObject(reg))
client.AddObjectInstance(betwixt.OMA_OBJECT_LWM2M_DEVICE, 0)
client.EnableObject(betwixt.OMA_OBJECT_LWM2M_ACCESS_CONTROL, objects.NewExampleAccessControlObject(reg))
client.AddObjectInstances(betwixt.OMA_OBJECT_LWM2M_ACCESS_CONTROL, 0, 1, 2)
client.EnableObject(betwixt.OMA_OBJECT_LWM2M_CONNECTIVITY_MONITORING, objects.NewExampleConnectivityMonitoringObject(reg))
client.AddObjectInstance(betwixt.OMA_OBJECT_LWM2M_CONNECTIVITY_MONITORING, 0)
client.EnableObject(betwixt.OMA_OBJECT_LWM2M_FIRMWARE_UPDATE, objects.NewExampleFirmwareUpdateObject(reg))
client.AddObjectInstance(betwixt.OMA_OBJECT_LWM2M_FIRMWARE_UPDATE, 0)
client.EnableObject(betwixt.OMA_OBJECT_LWM2M_LOCATION, objects.NewExampleLocationObject(reg))
client.EnableObject(betwixt.OMA_OBJECT_LWM2M_CONNECTIVITY_STATISTICS, objects.NewExampleConnectivityStatisticsObject(reg))
}
Implementing a LWM2M Object (LWM2M 'Device' Object)
import (
. "github.com/zubairhamed/betwixt"
"time"
)
type DeviceObject struct {
Model ObjectDefinition
currentTime time.Time
utcOffset string
timeZone string
}
func (o *DeviceObject) OnExecute(instanceId int, resourceId int, req Lwm2mRequest) Lwm2mResponse {
return Changed()
}
func (o *DeviceObject) OnCreate(instanceId int, resourceId int, req Lwm2mRequest) Lwm2mResponse {
return Created()
}
func (o *DeviceObject) OnDelete(instanceId int, req Lwm2mRequest) Lwm2mResponse {
return Deleted()
}
func (o *DeviceObject) OnRead(instanceId int, resourceId int, req Lwm2mRequest) Lwm2mResponse {
if resourceId == -1 {
// Read Object Instance
} else {
// Read Resource Instance
var val Value
switch resourceId {
case 0:
val = String("Open Mobile Alliance")
break
case 1:
val = String("Lightweight M2M Client")
break
case 2:
val = String("345000123")
break
case 3:
val = String("1.0")
break
case 6:
val = Integer(POWERSOURCE_INTERNAL, POWERSOURCE_USB)
break
case 7:
val = Integer(3800, 5000)
break
case 8:
val = Integer(125, 900)
break
case 9:
val = Integer(100)
break
case 10:
val = Integer(15)
break
case 11:
val = MultipleIntegers(Integer(0))
break
case 13:
val = Time(o.currentTime)
break
case 14:
val = String(o.utcOffset)
break
case 15:
val = String(o.timeZone)
break
case 16:
val = String(string(BINDINGMODE_UDP))
break
default:
break
}
return Content(val)
}
return NotFound()
}
func (o *DeviceObject) OnWrite(instanceId int, resourceId int, req Lwm2mRequest) Lwm2mResponse {
val := req.GetMessage().Payload
switch resourceId {
case 13:
break
case 14:
o.utcOffset = val.String()
break
case 15:
o.timeZone = val.String()
break
default:
return NotFound()
}
return Changed()
}
func (o *DeviceObject) Reboot() Value {
return Empty()
}
func (o *DeviceObject) FactoryReset() Value {
return Empty()
}
func (o *DeviceObject) ResetErrorCode() string {
return ""
}
func NewExampleDeviceObject(reg Registry) *DeviceObject {
return &DeviceObject{
Model: reg.GetDefinition(OMA_OBJECT_LWM2M_DEVICE),
currentTime: time.Unix(1367491215, 0),
utcOffset: "+02:00",
timeZone: "+02:00",
}
}
Minimal LWM2M Server (See /examples/server)
package main
import (
"github.com/zubairhamed/betwixt"
. "github.com/zubairhamed/betwixt/examples/server"
)
func main() {
s := NewDefaultServer("8081")
registry := betwixt.NewDefaultObjectRegistry()
s.UseRegistry(registry)
s.Start()
}
Limitations
- No dTLS support.
LWM2M - Short of it
-
Device Management Standard out of OMA
-
Lightweight and compact binary protocol based on CoAP
-
Targets as light as 8-bit MCUs