Embedded C Client Library - Introduction

Embedded C client for interacting with the Internet of Things Foundation.

Dependencies

1. Embedded C MQTT Client

Embedded C Client Library - Devices

iotfclient is client for the Internet of Things Foundation service. You can use this client to connect to the service, publish events and subscribe to commands.

Initialize

There are 2 ways to initialize the iotfclient.

Passing as parameters

The function initialize takes the following details to connect to the IoT Foundation service

• client - Pointer to the iotfclient
• org - Your organization ID
• type - The type of your device
• id - The ID of your device
• authmethod - Method of authentication (the only value currently supported is “token”)
• authtoken - API key token (required if auth-method is “token”)

#include "iotfclient.h"
   ....
   ....
   Iotfclient client;
   //quickstart
   rc = initialize(&client,"quickstart","iotsample","001122334455",NULL,NULL);
   //registered
   rc = initialize(&client,"orgid","type","id","token","authtoken");
   ....

Using a configuration file

The function initialize_configfile takes the configuration file path as a parameter.

#include "iotfclient.h"
   ....
   ....
   char *filePath = "./device.cfg";
   Iotfclient client;
   rc = initialize_configfile(&client, filePath);
   ....

The configuration file must be in the format of

org=$orgId
type=$myDeviceType
id=$myDeviceId
auth-method=token
auth-token=$token

Connect

After initializing the iotfclient, you can connect to the Internet of Things Foundation by calling the connectiotf function

#include "iotfclient.h"
   ....
   ....
   Iotfclient client;
   char *configFilePath = "./device.cfg";

   rc = initialize_configfile(&client, configFilePath);

   if(rc != SUCCESS){
       printf("initialize failed and returned rc = %d.\n Quitting..", rc);
       return 0;
   }

   rc = connectiotf(&client);

   if(rc != SUCCESS){
       printf("Connection failed and returned rc = %d.\n Quitting..", rc);
       return 0;
   }
   ....

Handling commands

When the device client connects, it automatically subscribes to any command for this device. To process specific commands you need to register a command callback function by calling the function setCommandHandler. The commands are returned as

• commandName - name of the command invoked
• format - e.g json, xml
• payload

#include "iotfclient.h"

void myCallback (char* commandName, char* format, void* payload)
{
   printf("The command received :: %s\n", commandName);
   printf("format : %s\n", format);
   printf("Payload is : %s\n", (char *)payload);
}
 ...
 ...
 char *filePath = "./device.cfg";
 rc = connectiotfConfig(filePath);
 setCommandHandler(myCallback);

 yield(1000);
 ....

Note : yield function must be called periodically to receive commands.

Publishing events

Events can be published by using

• eventType - Type of event to be published e.g status, gps
• eventFormat - Format of the event e.g json
• data - Payload of the event
• QoS - qos for the publish event. Supported values : QOS0, QOS1, QOS2

#include "iotfclient.h"
 ....
 rc = connectiotf (org, type, id , authmethod, authtoken);
 char *payload = {\"d\" : {\"temp\" : 34 }};

 rc= publishEvent("status","json", "{\"d\" : {\"temp\" : 34 }}", QOS0); 
 ....

Disconnect Client

Disconnects the client and releases the connections

#include "iotfclient.h"
 ....
 rc = connectiotf (org, type, id , authmethod, authtoken);
 char *payload = {\"d\" : {\"temp\" : 34 }};

 rc= publishEvent("status","json", payload , QOS0);
 ...
 rc = disconnect();
 ....