Comments on: Chapter 12: The Internet of Things

By: Gustavo

Gustavo — Sat, 04 Nov 2017 14:36:19 +0000

PHP5 does not install anymore, should update to php7.0 on commands listed on page 493.

By: Craig Clark

Craig Clark — Tue, 29 Aug 2017 00:05:55 +0000

On page 510, the setting “hostname=myaccountname@gmail.com” in /etc/ssmtp/ssmtp.config caused the error “ssmtp: Cannot open smtp.gmail.com:587”. Changing it to “hostname=raspberrypi” which is the hostname of my raspberry pi corrected the problem.

By: Ubaid

Ubaid — Fri, 11 Aug 2017 04:22:17 +0000

Hello derek,

On your example for “IBM IoT MQTT C++” on page 520, the code exits with an rc state of 5.
I cannot figure out the issue with the same…

#include #include #include #include #include "MQTTClient.h" #define CPU_TEMP "/sys/class/thermal/thermal_zone0/temp" using namespace std;


#define ADDRESS "tcp://(MY_URL).messaging.internetofthings.ibmcloud.com:1883"

#define CLIENTID "d:(MY_URL):RaspberryPi:erpi01"

#define AUTHMETHOD "use-token-auth"

#define AUTHTOKEN "(MY_TOKEN)"

#define TOPIC "iot-2/evt/status/fmt/json"

#define QOS 1

#define TIMEOUT 10000L
float getCPUTemperature(){

int CPUTemp;

fstream fs;

fs.open(CPU_TEMP, fstream::in);

fs >> CPUTemp;

fs.close();

return (((float)CPUTemp)/1000);

}
int main(int argc, char* argv[]) {

MQTTClient client;

MQTTClient_connectOptions opts = MQTTClient_connectOptions_initializer;

MQTTClient_message pubmsg = MQTTClient_message_initializer;

MQTTClient_deliveryToken token;

MQTTClient_create(&client, ADDRESS, CLIENTID, MQTTCLIENT_PERSISTENCE_NONE, NULL);
opts.keepAliveInterval = 20;

opts.cleansession = 1;

opts.username = AUTHMETHOD;

opts.password = AUTHTOKEN;

int rc;

if ((rc = MQTTClient_connect(client, &opts)) != MQTTCLIENT_SUCCESS)

{

cout<<"Failed to connect "<
return -1;

}
stringstream message;

message <<"{\"d\":{\"Temp\":"< pubmsg.payload = (char*) message.str().c_str(); pubmsg.payloadlen = message.str().length(); pubmsg.qos = QOS; pubmsg.retained = 0; MQTTClient_publishMessage(client, TOPIC, &pubmsg, &token); cout<< "Waiting for " << (int) (TIMEOUT/1000) << "seconds for pub of"< rc = MQTTClient_waitForCompletion(client, token, TIMEOUT); cout<<"Message with token"<< (int)token<<"delivered"< MQTTClient_disconnect(client,10000); MQTTClient_destroy(&client); return rc; }

Do we have to do anything else after creating a device on IBM bluemix..?? Frankly they have changed the entire interface of bluemix.

By: Steve Neave

Steve Neave — Sat, 21 Jan 2017 17:41:37 +0000

Hi Derek,
Love your book. Love it to bits. But I got stuck on page 502 trying to install OpenSSL.

pi@raspberrypi:~ $ sudo apt install openssl libssl-dev
Reading package lists… Done
Building dependency tree
Reading state information… Done
openssl is already the newest version.
The following NEW packages will be installed:
libssl-dev libssl-doc
0 upgraded, 2 newly installed, 0 to remove and 0 not upgraded.
Need to get 0 B/2,262 kB of archives.
After this operation, 6,480 kB of additional disk space will be used.
Selecting previously unselected package libssl-dev:armhf.
dpkg: unrecoverable fatal error, aborting:
unable to open files list file for package `libvorbisfile3:armhf’: Structure needs cleaning
E: Sub-process /usr/bin/dpkg returned an error code (2)

Steve
RPi3, default O/S, Linux newbie

By: admin

admin — Sun, 28 Aug 2016 23:01:33 +0000

Thanks, it must have been updated and that is very useful to know. Kind regards, Derek.

By: R. Gutmann

R. Gutmann — Sat, 27 Aug 2016 19:40:09 +0000

In Listing 12.6 I believe the line
SocketClient sc( “thingpeak.com”,80);
should be
SocketClient sc(“api.thingspeak.com”, 80);