ESP32 Arduino : IBM Watson Visual Recognition of Images with cURL

Abhishek Ghosh

By Abhishek Ghosh March 15, 2019 1:03 am Updated on March 15, 2019

ESP32 Arduino : IBM Watson Visual Recognition of Images with cURL

IBM Watson Visual Recognition of Images Supports cURL. ESP32 Arduino Can Send cURL of Images and Receive JSON Response on Serial Monitor. Demo of Watson Visial Recognition can be found on this URL :

https://www.ibm.com/watson/services/visual-recognition/demo/#demo

1	https://www.ibm.com/watson/services/visual-recognition/demo/#demo

WARNING : This testing project’s Arduino/ESP32 code may return blank response at present. It is for pointing to understand how the platform can be used from just ESP32.

The Lite (free) plan of IBM Watson Visual Recognition allows 1000 requests per month. That should be enough for testing and ordinary works. IBM Watson Visual Recognition supports up to 10 MB image size. Detailed documentation can be found on :

https://console.bluemix.net/apidocs/visual-recognition
https://github.com/IBM-Bluemix-Docs/visual-recognition/blob/master/getting-started.md
https://console.bluemix.net/docs/services/visual-recognition/tutorial-custom-classifier.html#tutorial-custom-classifier
https://www.ibm.com/watson/services/visual-recognition/demo/#demo

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https://console.bluemix.net/apidocs/visual-recognition

https://github.com/IBM-Bluemix-Docs/visual-recognition/blob/master/getting-started.md

https://console.bluemix.net/docs/services/visual-recognition/tutorial-custom-classifier.html#tutorial-custom-classifier

https://www.ibm.com/watson/services/visual-recognition/demo/#demo

ESP32 Arduino IBM Watson Visual Recognition of Images with cURL

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First we need an running Watson Visual Recognition service on IBM Cloud. Then generate a credidential. After generating the API, we will get example cURL (change the API key) like this :

curl -u "apikey:big_api_key_here" "https://gateway.watsonplatform.net/visual-recognition/api/v3/classify?url=https://watson-developer-cloud.github.io/doc-tutorial-downloads/visual-recognition/640px-IBM_VGA_90X8941_on_PS55.jpg&version=2018-03-19"

1	curl -u "apikey:big_api_key_here" "https://gateway.watsonplatform.net/visual-recognition/api/v3/classify?url=https://watson-developer-cloud.github.io/doc-tutorial-downloads/visual-recognition/640px-IBM_VGA_90X8941_on_PS55.jpg&version=2018-03-19"

apikey is their set & allowed user name. If you run cURL appending -v with the above, you will see the request headers :

> GET /visual-recognition/api/v3/classify?url=https://watson-developer-cloud.github.io/doc-tutorial-downloads/visual-recognition/640px-IBM_VGA_90X8941_on_PS55.jpg&version=2018-03-19 HTTP/1.1
> Host: gateway.watsonplatform.net
> Authorization: Basic YXBpa2V5OmhBUG9lbzFGTUVxU3BBNjJ
> User-Agent: curl/7.47.0
> Accept: */*

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> GET /visual-recognition/api/v3/classify?url=https://watson-developer-cloud.github.io/doc-tutorial-downloads/visual-recognition/640px-IBM_VGA_90X8941_on_PS55.jpg&version=2018-03-19 HTTP/1.1

> Host: gateway.watsonplatform.net

> Authorization: Basic YXBpa2V5OmhBUG9lbzFGTUVxU3BBNjJ

> User-Agent: curl/7.47.0

> Accept: */*

It is an HTTP GET request with the above parameters. You can try this code for ESP32 :

#include <WiFi.h>
#include <WiFiMulti.h>
#include <HTTPClient.h>
#include <base64.h>

#define USE_SERIAL Serial 


// <------- CHANGE PARAMETERS BELOW THIS LINE ------------>

const char* ssid = "your hotspot";
const char* password = "abcdefgh";

#define IMAGE "https://watson-developer-cloud.github.io/doc-tutorial-downloads/visual-recognition/640px-IBM_VGA_90X8941_on_PS55.jpg"
#define TOKEN "your-api"
#define DATE "2018-03-19" 

// <------- CHANGE PARAMETERS ABOVE THIS LINE ------------>

String urlPath = "/visual-recognition/api/v3/classify?url=" IMAGE "&version=" DATE;
String urlHost = "gateway.watsonplatform.net";
int urlPort = 443;
String authHeader;

void setup() {
  Serial.begin(115200); Serial.println(); 
  initWifi(); 
    authHeader = "Authorization: Basic " + base64::encode("apikey:" TOKEN) + "\r\n";
}

void loop() {
  doWiFiClientSecure();
  delay(10000);
}

void doWiFiClientSecure() {
 WiFiClientSecure client;
 Serial.print("connect: "); Serial.println(urlHost);
 while ( ! client.connect(urlHost.c_str(), urlPort)) {
    Serial.print(".");
 }
 Serial.println("Connected");
 String msg = "GET" + urlPath + " HTTP/1.1\r\n"
                "Host: " + urlHost + "\r\n"
                "" + authHeader + ""
                "Content-Type: application/json\r\n"
                "User-Agent: curl/7.47.0\r\n";
                
 client.print(msg);
 Serial.print(msg);

 Serial.print("\n*** Request sent, receiving response...");
 while (!!!client.available()) {
    delay(50);
 Serial.print(".");
  }
  
Serial.println();
Serial.println("Got response");  
  while(client.available()){
  Serial.write(client.read());
  }
Serial.println(); Serial.println("closing connection");
  client.stop();
}

void initWifi() {
  Serial.print("Connecting to: "); Serial.print(WiFi.SSID());
  WiFi.mode(WIFI_STA);   
  WiFi.begin(ssid, password);  
  while (WiFi.status() != WL_CONNECTED) {
     delay(250);
     Serial.print(".");
  }
  
  Serial.println("");
  Serial.print("WiFi connected, IP address: "); Serial.println(WiFi.localIP());

}

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#include <WiFi.h>

#include <WiFiMulti.h>

#include <HTTPClient.h>

#include <base64.h>

#define USE_SERIAL Serial

// <------- CHANGE PARAMETERS BELOW THIS LINE ------------>

const char* ssid = "your hotspot";

const char* password = "abcdefgh";

#define IMAGE "https://watson-developer-cloud.github.io/doc-tutorial-downloads/visual-recognition/640px-IBM_VGA_90X8941_on_PS55.jpg"

#define TOKEN "your-api"

#define DATE "2018-03-19"

// <------- CHANGE PARAMETERS ABOVE THIS LINE ------------>

String urlPath = "/visual-recognition/api/v3/classify?url=" IMAGE "&version=" DATE;

String urlHost = "gateway.watsonplatform.net";

int urlPort = 443;

String authHeader;

void setup() {

Serial.begin(115200); Serial.println();

initWifi();

authHeader = "Authorization: Basic " + base64::encode("apikey:" TOKEN) + "\r\n";

}

void loop() {

doWiFiClientSecure();

delay(10000);

}

void doWiFiClientSecure() {

WiFiClientSecure client;

Serial.print("connect: "); Serial.println(urlHost);

while ( ! client.connect(urlHost.c_str(), urlPort)) {

Serial.print(".");

}

Serial.println("Connected");

String msg = "GET" + urlPath + " HTTP/1.1\r\n"

"Host: " + urlHost + "\r\n"

"" + authHeader + ""

"Content-Type: application/json\r\n"

"User-Agent: curl/7.47.0\r\n";

client.print(msg);

Serial.print(msg);

Serial.print("\n*** Request sent, receiving response...");

while (!!!client.available()) {

delay(50);

Serial.print(".");

}

Serial.println();

Serial.println("Got response");

while(client.available()){

Serial.write(client.read());

}

Serial.println(); Serial.println("closing connection");

client.stop();

}

void initWifi() {

Serial.print("Connecting to: "); Serial.print(WiFi.SSID());

WiFi.mode(WIFI_STA);

WiFi.begin(ssid, password);

while (WiFi.status() != WL_CONNECTED) {

delay(250);

Serial.print(".");

}

Serial.println("");

Serial.print("WiFi connected, IP address: "); Serial.println(WiFi.localIP());

}

Open serial monitor. You will see this output :

Got response

closing connection
connect: gateway.watsonplatform.net
Connected
GET/visual-recognition/api/v3/classify?url=https://watson-developer-cloud.github.io/doc-tutorial-downloads/visual-recognition/640px-IBM_VGA_90X8941_on_PS55.jpg&version=2018-03-19 HTTP/1.1
Host: gateway.watsonplatform.net
Authorization: Basic YXBpa2V5OmhBUG9lbzFGTUVxU
Content-Type: application/json
User-Agent: curl/7.47.0

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Got response

closing connection

connect: gateway.watsonplatform.net

Connected

GET/visual-recognition/api/v3/classify?url=https://watson-developer-cloud.github.io/doc-tutorial-downloads/visual-recognition/640px-IBM_VGA_90X8941_on_PS55.jpg&version=2018-03-19 HTTP/1.1

Host: gateway.watsonplatform.net

Authorization: Basic YXBpa2V5OmhBUG9lbzFGTUVxU

Content-Type: application/json

User-Agent: curl/7.47.0

This output header indicating the logic is correct.

Unplug ESP32 after once run. The code will continiously ping the server. Notice the blank output. Although I have not used JsonHttpClient, these problems are not rare. I modified my old codes for IBM Watson IoT for testing.

ESP32 Arduino : IBM Watson Visual Recognition of Images with cURL

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