Manage all the things, small and big, with open source LwM2M implementations

Benjamin Cabé* – Eclipse Foundation

* many thanks to Julien Vermillard for most of the slides!

Device Management

● Configure the device○ Reboot○ Update APN, current date/time, …

● Update the software (and firmware)● Manage the software

○ Change settings○ Access logs

● Monitor and gather connectivity statistics○ Amount of sent/received data○ Number of SMS received/sent

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Device Management

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Device Management server(not necessarily the server used for

IoT application data)

● Has security credentials for devices on the field (X.509 certificate, public key, …)

● Provides high-level API for batch updates

● May integrate with IT backendIoT Device

● Runs a device management agent, usually in the firmware

● Embeds a private/public key pair to cipher communication

● Has DM server’s public key to authenticate it is talking to intended server

D.M. standards protocols

● Usual suspects:○ TR-069○ OMA-DM○ Lightweight M2M

● Goals: provide a way to manage fleets of devices that is application-agnostic

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Lightweight M2M

● A new Open Mobile Alliance standard

● An OMA-DM successor for M2M targets

● Built on top of CoAP○ much lighter than OMA-DM or TRS-069

○ enables the use of SMS for wakeup (or any REST interaction really!)

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Lightweight M2M (LwM2M)

● An Open Mobile Alliance standard● A « reboot » of OMA-DM for M2M● Built on top of CoAP

○ much lighter than OMA-DM or TRS-069○ enables the use of SMS for wakeup (or any

REST interaction really!)● REST API for Device Management● Standard objects for Security, Location,

Firmware, …○ and also: IPSO Smart Objects, 3rd party, …

LWM2M features

● Firmware upgrade (in band or over HTTP)

● Device monitoring and configuration

● Server provisioning (bootstraping)

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LWM2M: standard objects

● Device

● Server

● Connectivity monitoring

● Connectivity statistics

● Location

● Firmware

LwM2M objects have a numerical identifier (Device = 3, Location = 6, …)

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LWM2M URIs

URLs:

/{object}/{instance}/{resource}

Example: /6/0 = whole position object (binary TLV)/6/0/2 = only the altitude value

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LeshanOpen-source Lightweight M2M for Java

Leshan

A Java library for implementing LwM2M servers (and clients)

Friendly for any Java developer (no framework, few dependencies)

But also a Web UI for discovering and testing the protocol

Features

Client initiated bootstrap

Registration/Deregistration

Read, Write, Create objects

TLV encoding/decoding

OSGi-friendly

Features (cont’d)

DTLS Pre shared key

DTLS Raw public key

Standalone web-UI for testing

Server

Simple Java library

Build using “mvn install”

Based on Californium and Scandium

Under refactoring for accepting other CoAP lib

Server API examplepublic void start() { // Build LWM2M server LeshanServerBuilder builder = new LeshanServerBuilder(); lwServer = builder.build(); lwServer.getClientRegistry().addListener(new ClientRegistryListener() {

@Override public void registered(Client client) { System.out.println("New registered client with endpoint: " + client.getEndpoint()); }

@Override public void updated(Client clientUpdated) { System.out.println("Registration updated"); }

@Override public void unregistered(Client client) { System.out.println("Registration deleted"); }

});

// start lwServer.start(); System.out.println("Demo server started");}

Server API example

// prepare the new valueLwM2mResource currentTimeResource = new LwM2mResource(13, Value.newDateValue(new Date()));

// send a write request to a client

WriteRequest writeCurrentTime = new WriteRequest(client, 3, 0, 13, currentTimeResource, ContentFormat.TEXT, true);

ClientResponse response = lwServer.send(writeCurrentTime);

System.out.println("Response to write request from client " + client.getEndpoint() + ": " + response.getCode());

Client

Under construction! API will probably change

Create objects, answer to server requests

DTLS supported in master

Check out: leshan-client-example

Next steps

Eclipse.org migrationX.509 DTLSCoAP shim, CoAP TCPStable API for June (inc. client polishing)

And also:JSON content-typeSMSServer initiated bootstrap

Eclipse Wakaama

Lightweight M2M implementation in C

Photo credits: https://www.flickr.com/photos/30126248@N00/2890986348

Wakaama

A C client and server implementation of LwM2M

Not a shared library (.so/.dll)

POSIX compliant and embedded friendly

Plug your own IP stack and DTLS implementation

Features

Register, registration update, deregister

Read, write resources

Read, write, create, delete object instances

TLV or plain text

Observe

lwm2m_object_t * get_object_device(){ lwm2m_object_t * deviceObj; deviceObj = (lwm2m_object_t *)lwm2m_malloc(sizeof(lwm2m_object_t));

if (NULL != deviceObj) { memset(deviceObj, 0, sizeof(lwm2m_object_t)); deviceObj->objID = 3;

deviceObj->readFunc = prv_device_read; deviceObj->writeFunc = prv_device_write; deviceObj->executeFunc = prv_device_execute; deviceObj->userData = lwm2m_malloc(sizeof(device_data_t));

if (NULL != deviceObj->userData) { ((device_data_t*)deviceObj->userData)->time = 1367491215; strcpy(((device_data_t*)deviceObj->userData)->time_offset, "+01:00"); } else { lwm2m_free(deviceObj); deviceObj = NULL; } }

return deviceObj;}

Create objects!

objArray[0] = get_object_device();if (NULL == objArray[0]){ fprintf(stderr, "Failed to create Device object\r\n"); return -1;}

objArray[1] = get_object_firmware();if (NULL == objArray[1]){ fprintf(stderr, "Failed to create Firmware object\r\n"); return -1;}

objArray[2] = get_test_object();if (NULL == objArray[2]){ fprintf(stderr, "Failed to create test object\r\n"); return -1;}

lwm2mH = lwm2m_init(prv_connect_server, prv_buffer_send, &data);if (NULL == lwm2mH){ fprintf(stderr, "lwm2m_init() failed\r\n"); return -1;}result = lwm2m_configure(lwm2mH, "testlwm2mclient", BINDING_U, NULL, OBJ_COUNT, objArray);...result = lwm2m_start(lwm2mH);

ConfigureWakaama

while (0 == g_quit){ struct timeval tv; tv.tv_sec = 60; tv.tv_usec = 0;

/* * This function does two things: * - first it does the work needed by liblwm2m (eg. (re)sending some packets). * - Secondly it adjust the timeout value (default 60s) depending on the * state of the transaction (eg. retransmission) and the * time between the next operation */ result = lwm2m_step(lwm2mH, &tv); if (result != 0) { fprintf(stderr, "lwm2m_step() failed: 0x%X\r\n", result); return -1; }}

Active loop

Next?

Device initiated bootstrap

More examples:https://github.com/kartben/Wakaama-mbed

Server?

Block transfer?

Hack it into real devices!

… DEMO TIME!

Spark Core

● Cortex-M3 STM32, ● RAM/ROM 20/128k, 72MHz● WiFi

Wakaama + TinydTLS-0.5

Functions: dTLS (PSK)

LwM2M Objects: device

Footprint:

“empty”-App: 75.6 KB Flash / 13.1 KB RAM

simple-lwm2m: 107 KB Flash / 15.2 KB RAM (overhead = 32KB / 3.1kB!)

U-blox MBed.org

● Cortex-M3 (NXP LPC1768), ● RAM/ROM 20/128k, 96MHz● GPRS

Functions: observe, attribute:

Objects: server, security, device, conn_m, firmware, location

Footprint (RTOS + commandline + lwm2m stack): 84 KB Flash / 22 KB RAM

Arduino Mega

● ATmega2560 ● RAM/ROM 8/256k, 16MHz● Ethernet

Functions: observe, attribute

Objects: server, security, device, conn_m, firmware, location

Footprint (C++ wrapper + simulator + lwm2m stack): 67 KB Flash / 5 KB RAM

Lua binding

https://github.com/sbernard31/lualwm2m

With DTLS support using:https://github.com/sbernard31/luadtlsbinding on top of TinyDTLS (http://tinydtls.sf.net)

How to help?

Use it! Report bugs, issue, missing features

Write documentation

Talk about Wakaama and Leshan, they are cool!

Contribute code

Questions?

https://dev.eclipse.org/mailman/listinfo/leshan-dev

https://dev.eclipse.org/mailman/listinfo/wakaama-dev

Thanks!

benjamin@eclipse.org@kartben

http://iot.eclipse.org