Maker of Things - the open IoT cloud for makers chapter.

2015.9.7
Taipei
Maker of Things
Open IoT Cloud for Makers
Innovation of Things
Mokoversity
姓名標示-非商
業性 4.0 國際

Lecturer
Jollen, Founder of WoT.City
!
Jollen is a passionate software
developer with a breadth of technical
experience with software
engineering, web technologies,
embedded systems, operating
systems and distributed systems.
!
Jollen specializes in open source
software business model and its
strategy planning. He is also the
founder of Mokoversity and WoT.City.
!
Please Email Jollen through
jollen@jollen.org

1
ARM mbed
The next big OS to rock the
world will be little.

3 Physical Web
The future of the IoT is URLs.

Constrained!
Device
High
Performance
MCU
WiFi MCU SBC
Server !
Farms
Platform
Portfolio
Legacy MCUs
ARM mbed OS、
Neuclio
ESP8266、
NodeMCU、
EMW3165
Intel Edison、
Qualcomm
Dragonboard 410c
IoT Diagram
(Use
Scenario)
WoT
Architecture
IoT Protocols
TD

Web of Things
《ARM mbed Practice: RTOS, IoT Client & IoT Cloud》 Copyright (C) 2015 Moko365 Inc. 僅供 QUALCOMM 內部使⽤用.

the Web of Things reuses existing and well-known
Web standards[1][2] used in the programmable Web
(e.g., REST, HTTP, JSON), semantic Web (e.g., JSON-LD,
Microdata, etc.), the real-time Web (e.g., Websockets)
and the social Web (e.g., oauth or social networks).
!
—Wikipedia
Web of Things

HTTP
Websocket
CoAP
http://
ws://
coap://

IP
UDP
SMTPDNS HTTP
TCP
CoAP FTP
Ethernet
Layering of Protocols

IoT WoT
連結⽅方式 Bluetooth HTTP
數據管理 Centerlized Decenterlized
Things Objects RESTful Objects
應⽤用開發模式 Native Web (SPA)
硬件概念 Sensor Device
Physical Web
(Sensor Fusion)
Figure: Thinking in WoT. Copyright (C) 2014 Mokoversity Inc.
IoT vs WoT: Methdology

IoT WoT
Connectivity Machine to Machine
LWM2M
Machine to Web
Networking TCP / UDP HTTP / REST / CoAP
Things Sensor Device RESTful Objects
Data Streaming Data Time-Series Data
Discover MQTT Publish / Subscribe
IoT vs WoT: Connectivity

Internet of Things
Web of Things
An Application Layer that simplifies the creation of
Internet of Things applications
* of Things

Thinking in WoT
IoT WoT
连接⽅方式 Bluetooth HTTP
数据管理哲学 Centerlized Decenterlized
Things Objects RESTful Objects
IoT App Native Web (SPA)
硬件设计哲学 Sensor Device
Physical Web
(Sensor Fusion)

ARM mbed
mbed OS
We are creating a modern full-stack operating
system that is designed speciﬁcally for ARM
Cortex®-M-based MCUs; the worlds leading 32-
bit microcontrollers that already sell in the
billions.
!
mbed Device Server
Analogous to a Web Server that accepts
connections from mobile phones or web browsers,
a Device Server handles the connections from IoT
devices.
!
mbed Tools
online compiler (Web IDE), SDK, HDK and etc.

mbed OS
mbed Device Server
mbed Tools

Source: http://mbed.org/technology/os/
mbed OS
mbed™ OS is an operating system for IoT devices
and is especially well-suited to run in energy
constrained environments.

mbed RTOS
Thread
Mutex
Semaphore
Message Queue
Mail
Memory Poll

mbed Libraries
Analog I/O
Digital I/O
Timers
Digital Interface
Real-time Operating System
File System
USB (Device and Host)
Networking

Connectivity Protocol Stack
Bluetooth Low Energy
Cellular
Ethernet
Thread
Wi-Fi
Zigbee IP
Zigbee NAN
6LoWPAN

mbed Memory Sections
RW Data
Program
RAM
Flash
RW Data
Program
ZI = 0
RW Data
Stack
Heap

mbed Threads
RAM
Flash
RW Data
ZI: Timer Stack
ZI: Idle Stack
ZI
Scheduler Stack
Main Thread Stack
Head
When you use the RTOS, before explicitly
initializing any additional thread, you will
have 4 separate stacks:
!
• The stack of the Main Thread (executing
the main function).
!
• The Idle Thread executed each time all
the other threads are waiting for external,
or scheduled events. This is particularly
useful to implement energy saving
strategies. (ie sleep).
!
• The Timer Thread that executes all the
time scheduled tasks (periodic and non
periodic).
!
• The stack of OS Scheduler itself (also
used by the ISRs).

mbed Timer
#include "mbed.h"
Timer t;
int main() {
t.start();
printf("Hello World!n");
t.stop();
printf("The time taken was %f secondsn", t.read());
}
See: https://developer.mbed.org/handbook/Timer

mbed Thread API
#include "mbed.h"
#include "rtos.h"
DigitalOut led1(LED1);
DigitalOut led2(LED2);
void led2_thread(void const *args) {
while (true) {
led2 = !led2;
Thread::wait(1000);
}
}
int main() {
Thread thread(led2_thread);
while (true) {
led1 = !led1;
Thread::wait(500);
}
}
See: https://developer.mbed.org/handbook/RTOS#thread

mbed Thread Priority
int main() {
Thread thread(led2_thread);
thread.set_priority(osPriorityNormal);
!
while (true) {
led1 = !led1;
Thread::wait(500);
}
}

mbed Thread States

mbed Mutex
See: https://developer.mbed.org/handbook/RTOS
#include "mbed.h"
#include "rtos.h"
Mutex stdio_mutex;
void notify(const char* name, int state) {
stdio_mutex.lock();
printf("%s: %dnr", name, state);
stdio_mutex.unlock();
}
void test_thread(void const *args) {
while (true) {
notify((const char*)args, 0); Thread::wait(1000);
notify((const char*)args, 1); Thread::wait(1000);
}
}
int main() {
Thread t2(test_thread, (void *)"Th 2");
test_thread((void *)"Th 1");
}

#include "mbed.h"
#include "rtos.h"
Semaphore two_slots(2);
void test_thread(void const *name) {
while (true) {
two_slots.wait();
printf("%snr", (const char*)name);
Thread::wait(1000);
two_slots.release();
}
}
int main (void) {
test_thread((void *)"Th 1");
}
mbed Semaphore
See: https://developer.mbed.org/handbook/RTOS

Layering of Protocols
IP
UDP
SMTPDNS HTTP
TCP
CoAP FTP
Ethernet

CoAP
CoAP 並不是要取代 HTTP，它是針對
Constrained Device 的 HTTP 需求。CoAP
（Constrained Application Protocol）是更
簡單且輕量化的 HTTP 技術，簡單的意思是，
CoAP 簡化了 HTTP 的內容，輕量化的意思
是，CoAP 採⽤用 UDP 進⾏行傳輸。

CoAP over UDP
UDP
IP
CoAP
WoT Server
IoT over the Web
Ethernet MAC
Ethernet PHY
Application
Transport
Network
Data Link
Physical
TLS (optional) Presentation / Session

HTTP over UDP
簡單來說，CoAP 可以看做是⼀一個 HTTP over
UDP 的技術。CoAP 是物聯網的重要技術，它
讓 Constrained Device 都能具備 HTTP 的
能⼒力。⼤大部份的 MCU 裝置都是 Constrained
Device，因此，就也像是 MCU + HTTP。

HTTP over TCP
TCP
IP
HTTP 1.1/2.0
WoT Server
the Web
Ethernet MAC
Ethernet PHY
Application
Transport
Network
Data Link
Physical

SPDY
因為 HTTP request/response headers 設
計上的⼀一些缺點，讓 HTTP 的網路傳輸效能無
法提昇。為解決這些問題，Google 便提出了
SPDY 協定。SPDY 協定後來成為 HTTP/2
（HTTP 2.0）的基礎。IETF 在 2015 年 5 ⽉月
正式發佈 HTTP/2 標準（RFC 7540）。
HTTP/2 是基於 TCP 協定，因此要讓物聯網裝
置使⽤用 HTTP over UDP 的話，⺫⽬目前仍必須使
⽤用 HTTP + QUIC + UDP 的堆疊。

HTTP/1.1 over SPDY+TCP
TCP
IP
HTTP
WoT Server
the Web
Ethernet MAC
Ethernet PHY
Application
Transport
Network
Data Link
Physical
SPDY + TLS Presentation / Session

QUIC
HTTP over TCP 的 ACK 會造成的⼀一些負擔，
因此如果讓 HTTP over UDP 的話，就可以解
決這個問題。Google 所提出的 QUIC（Quick
UDP Internet Connection）就是這樣的技
術。QUIC 可以讓 HTTP 基於 UDP 傳輸層，就
是 HTTP + QUIC + UDP。

HTTP over QUIC+UDP
HTTP/2 未來也可能在物聯網應⽤用上，扮演重
要⾓角⾊色。因為 HTTP request/response
headers 設計上的⼀一些缺點，讓 HTTP 的網路
傳輸效能無法提昇。為解決這些問題，Google
便提出了 SPDY 協定。SPDY 協定後來成為
HTTP/2（HTTP 2.0）的基礎。IETF 在
2015 年 5 ⽉月正式發佈 HTTP/2 標準（RFC
7540）。HTTP/2 是基於 TCP 協定，因此要
讓物聯網裝置使⽤用 HTTP over UDP 的話，⺫⽬目
前仍必須使⽤用 HTTP + QUIC + UDP 的堆
疊。

UDP + QUIC
IP
HTTP
WoT Server
IoT over the Web
Ethernet MAC
Ethernet PHY
Application
Transport
Network
Data Link
Physical
SPDY + QUIC Presentation / Session
HTTP over QUIC+UDP
UDP + QUIC
IP
HTTP
WoT Server
IoT over the Web
Ethernet MAC
Ethernet PHY
QUIC

HTTP/2 over QUIC
因為 HTTP/2 標準就是 SPDY 的內容，如果有
意在物聯網裝置上使⽤用 HTTP/2 的特性，就要
採⽤用 HTTP + SPDY + QUIC + UDP 的堆疊。
不過，Google 未來有意將 HTTP/2 over
QUIC 提交給 IETF，到時就能捨棄 HTTP +
SPDY + QUIC + UDP 的做法，畢竟這只是過
渡時期的解決⽅方案。

IP
HTTP/2
WoT Server
IoT over the Web
Ethernet MAC
Ethernet PHY
Application
Transport
Network
Data Link
Physical
QUIC + UDP
Presentation / Session
HTTP/2 over QUIC

CoAP-HTTP Translate
CoAP 並⾮非直接採⽤用 HTTP 標準，⽽而是透過轉
換（translate）的⽅方式將訊息對應成標準的
HTTP。CoAP 採納了 REST 架構，並且也是採
取 request/response 的模式。因此，要將
CoAP 轉換為 HTTP，或是將 HTTP 轉換為
CoAP，其實是⾮非常容易的。實際上，CoAP 只
對 request/response 的部份做轉換，也就是
CoAP 的 request 都能轉換為 HTTP request
headers；response 的部份亦同。

CoAP-HTTP
UDP
IP
CoAP
WoT Server
Ethernet MAC
Ethernet PHY
Application
Transport
Network
Data Link
Physical
TCP
IP
HTTP
WoT Client
the Web
Ethernet MAC
Ethernet PHY
TLS (optional)
IoT over the Web

Transferring HTTP Message
IP
TCP
HTTP
Ethernet
Interface
Web client
IP
TCP
HTTP
Ethernet
Interface
Web server
HTTP message
TCP segment

Transferring CoAP Message
IP
UDP
HTTP
Ethernet
Interface
Web client
IP
UDP
HTTP
Ethernet
Interface
Web server
CoAP message
UDP segment

TCP Connection
B
SYN
A
SYN-ACK
ACK
DATA
ACK
DATA
FIN
.
.
.

IoT/WoT Interoperability
Websocket
HTTP 1.1/2.0
CoAP
IoT
Cloud
IoT Device
IoT Device
IoT Device IoT Device
Mobile &
Client
IoT Proxy

Thread
A secure wireless mesh network for
smart home.
IEEE 802.15.4 MAC
IEEE 802.15.4 PHY
6LoWPAN (IPv6)
IP Routing
UDP + DTLS
Application
Thread
RFC 4944, RFC 4862, RFC 6775
RFC 1058, RFC 2080
RFC 768, RFC 6347, RFC 4279
RFC 4492v RFC 3315, 5007

6LoWPAN
IPv6 over Low power Wireless Personal
Area Networks.
For constrained IoT devices.
UDP
6LoWPAN
CoAP
EXI
TCP
IP
HTTP
HTML
the Web IoT + the Web

TCP/IP Protocol Stack
UDP
6LoWPAN (IPv6)
CoAP
WoT Application
TCP
IP
HTTP
HTML
the Web IoT + the Web
UDP
Ethernet MAC
Ethernet PHY
IEEE 802.15.4 MAC
IEEE 802.15.4 PHY
Application
Transport
Network
Data Link
Physical

Source: http://coap.technology
REST model for small
devices
!
Like HTTP, CoAP is based on the wildly
successful REST model: Servers make
resources available under a URL, and
clients access these resources using
methods such as GET, PUT, POST, and
DELETE.

Made for billions of
nodes
!
The Internet of Things will need billions of
nodes, many of which will need to be
inexpensive. CoAP has been designed to
work on microcontrollers with as low as 10
KiB of RAM and 100 KiB of code space (RFC
7228).

Existing skills
transfer
!
From a developer point of view, CoAP feels
very much like HTTP. Obtaining a value
from a sensor is not much different from
obtaining a value from a Web API.

ARM IoT Tutorial

https://www.youtube.com/watch?v=4bSr5x5gKvA
Ready for
integration
!
Since HTTP and CoAP share the REST
model, they can easily be connected using
application-agnostic cross-protocol
proxies. A Web client may not even notice
that it just accessed a sensor resource!

ARM mbed Priactice: CoAP
CoapPDU *pdu = new CoapPDU();
!
pdu->setType(CoapPDU::COAP_CONFIRMABLE);
pdu->setCode(CoapPDU::COAP_GET);
pdu->setToken((uint8_t*)"3210",4);
pdu->setMessageID(0x0005);
pdu->setURI((char*)"test",4);
!
// send packet
ret = send(sockfd,pdu->getPDUPointer(),pdu->getPDULength(),0);

cont…
// receive packet
ret = recvfrom(sockfd,&buffer,BUF_LEN,0,
(sockaddr*)&recvAddr,&recvAddrLen);
!
CoapPDU *recvPDU = new CoapPDU((uint8_t*)buffer,ret);
!
if(recvPDU->validate()) {
recvPDU->getURI(uriBuffer,URI_BUF_LEN,&recvURILen);
...
}

IoT & mbed Cloud - Device
Server

Analogous to a Web Server that accepts connections from
mobile phones or web browsers, a Device Server handles
the connections from Internet of Things (IoT) devices.
A Device Server is a key enabler for cloud service providers, operators and
enterprises to access the IoT growth market with production deployments,
bringing end node devices in to the world of web services.

Source: http://mbed.org/technology/device-server/

CoAP Server Architecture
Websocket
HTTP 1.1/2.0
CoAP
www.mokoversity.com
IoT
Cloud
IoT Device
IoT Device
IoT Proxy
1
2
IoT Device
2
3
Mobile &
Client
3

RESTful
UDP
M2M
Wireless Sensor Network
HTTP in Uniform way
Simple Cache
CoAP Features
IoT Device
IoT Device
IoT Proxy
1
2
IoT Device
2
3
Constrained Environment
3

Websocket
HTTP 1.1/2.0
CoAP
CoAP Portfolio
IoT
Cloud
IoT Device
IoT Device
IoT Proxy
(IoT Gateway)
1
2
IoT Device
2
3
Mobile &
Client
The Web of Things Protocol
3
Arch Pro
Arch Pro
Arch Pro
Seeeduino Cloud

http://50.128.14.32/1/jollenchen/sensor/dust/a
IoT Device Mobile
HTTP 1.1/2.0HTTP 1.1/2.0
Light-weight
Web server
Web
Frontend
Internet
Device Server: HTTP

IoT Device Mobile
HTTP 1.1/2.0
Streaming Data
Physical Object
Web
Frontend
Real-Time Data
Broker
ws://wot.city/object/jollenchen/sensor/dust/a
Device Server: WebSocket

Device Server Architecture
Websocket
HTTP 1.1/2.0
CoAP
IoT
Cloud
IoT Device
IoT Device
IoT Device IoT Device
Mobile &
Client
IoT Proxy

Architecture of 6LoWPAN
IoT Device
Mobile
Physical
Object Web
Frontend
Broker
IoT Device Proxy
(Gateway / Router)
IPv6, CoAP
6LoWPAN, CoAP
6LoWPAN, CoAP
IPv6, HTTP, HTML5

HTTP/CoAP/MQTT
HTTP
The Web protocol.
!
CoAP
The Web of Things
Protocol.
!
MQTT
The TCP Protocol.

HTTP CoAP MQTT
Type document oriented document oriented message oriented
Purpose server farms
constrained
devices
lightweight M2M
communications
Transport over TCP over UDP over TCP
Model Client/Server Client/Server Client/Server
Resolver URI REST Message
Interoperate one-to-one many-to-many
Architecture request/response request/response publish/subscribe
HTTP/CoAP/MQTT

MQTT Clients and Broker
Source: http://www.eclipse.org/community/eclipse_newsletter/2014/february/article2.php

mbed Tools
Digital Interface
Networking
HTTPD & REST API
Websocket
Device Server

Digital Interface
#include "mbed.h"
!
DigitalOut myled1(LED1);
!
int main() {
wait(0.8);

while(1) {
myled1 = 0;
wait(0.2);
myled1 = 1;
}
}

Networking
#include "mbed.h"
#include "EthernetInterface.h"
!
int main(void) {
// Ethernet Interface
EthernetInterface eth;
!
// use DHCP
eth->init();
!
//eth->init(“192.168.21.81”, "255.255.255.0", "192.168.21.2" );
!
if (eth->connect())
return -1;
!
printf("IP Address is %srn", eth->getIPAddress());
}

HTTPD
httpd = new HTTPD;
!
httpd->attach("/1/mbed/lpc1768/sensor/dust/sen12291p", &callback_api);
!
httpd->attach("/", "/local/");
!
httpd->start(80);

REST APIs over mbed
int main() {
printf("HTTP Server...rn");
!
eth = new EthernetInterface;
eth->init("192.168.21.81", "255.255.255.0", "192.168.21.2" );
!
if (eth->connect()) return -1;
!
printf("IP Address is %srn", eth->getIPAddress());
httpd = new HTTPD;
httpd->attach("/1/mbed/lpc1768/sensor/dust/sen12291p", &callback_api);
httpd->attach("/", "/local/");
httpd->start(80);
printf("httpd readyrn");
led2 = 1;
}

mbed WebSocket Server
IoT 扮演 Websocket server 的話，會有幾個技
術問題：

•
ARM mbed 要管理 client 端的
connections

•
需要更多的記億體來維護 client
connections

•
需要實作 Data push 的演算法

•
要考量 error handling 與 exception
handling

WebSocket Broker
WebSocket Broker 的使⽤用案例：
!

1.
佈署專⽤用的 Websocket broker server

2.
ARM mbed 將 data 即時推送（push）
到 Websocket broker server

3.
⽤用⼾戶（user）與 Websocket broker
server 建⽴立 Websocket connection

4.
⽤用⼾戶接收 Websocket broker server 的
即時資料

+
ARM
mbed
Available Now
ARM mbed with WoT

+
Coming Soon
Intel Edison with WoT

+
Under Development
Dragonboard 410c with WoT

+
Launch Soon
NodeMCU/ESP8266 with WoT

Constrained
IoT Devices
ws://wot.city
Websocket
Client 1
Client 2
...
1 to 1
n to n
Sender Client
Broker / Load Balancer
(Data Channel) Viewer Client
WebSocket Broker Server
Available Now

Constrained
IoT Devices
coap://wot.city
Websocket & HTTP
Client 1
Client 2
...
1 to 1
n to n
Sender Client
Broker / Load Balancer
(Data Channel) Viewer Client
CoAP Broker Server
Available Now
CoAP

WoT Platform Website
WoT Open Source
Contact
Angel List
https://wotcity.com/zh-tw
https://github.com/wotcity
hello@wotcity.com
https://angel.co/wot-city
(C) 2015 wotcity.com

Maker of Things - the open IoT cloud for makers chapter.

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