How to send char array of sensor data to websocket client ?

[happytm]

I have my websocket server based on advanced echo server working fine. with following code in loop section:

void loop() {

#if WEBSOCKETS
 while (WSserver.available()) {
    // if there is a client that wants to connect
    if(WSserver.poll()) {
      //accept the connection and register callback
      Serial.println("Accepting a new client!");
      WebsocketsClient client = WSserver.accept();
      client.onMessage(onMessage);
      
      // store it for later use
      allClients.push_back(client);
      
      }
      // check for updates in all clients
      pollAllClients();
      
      if (triggerProcessData == 1) { 
      processData(); 
      triggerProcessData = 0; 
      } 
  
       #if MQTT
       broker.loop();  // Don't forget to add loop for every broker and clients
       myClient.loop();
       #endif
       }  
#endif  
} // End of loop

Now Ihave callback function in the same skech like below:

const char* data = "Data requested";
 static int callback(void *data, int argc, char **argv, char **azColName) {
  Serial.print((char) '[');
  int i;
  for (i = 0; i<(argc); i++) {
    if(i)
    Serial.print((char) ',');
    Serial.printf("%s", argv[i] ? argv[i] : "NULL");
    }
    
  Serial.printf("],\n");
  
  return 0;
  }

Which prints data in my serial console based on request from javascript websocket client. Data in my serial console looks like below:

[1623287518,24785,1535,15,6,-22,292,49,89,250,76],
[1623287645,24785,1535,15,26,-52,294,51,94,224,48],
[1623287668,24785,1535,15,6,-22,292,49,44,249,81],
[1623287796,24785,1535,15,26,-53,294,46,97,229,36],

Now I want to send this data to websocket client who requested it but I do not know how to do it.

Can you please show me how to send the data to client?

Thanks.

[gilmaimon]

The post is a bit confusing, but please make sure you consult the wiki entries on sending messages

If you want to send binary data, you have 2 main options:

1. send it as raw bytes using sendBinary. The receiving end should also expect such raw data
2. serialize it and send it as text. You can serialize it as base64, or JSON for example

Gil

[happytm]

Thank you for a link to resource. I should have read it in first place. Now in my case argv[i] is array of strings so how should I send it ? As a binary or text?

Thanks.

[gilmaimon]

Thank you for a link to resource. I should have read it in first place. Now in my case argv[i] is array of strings so how should I send it ? As a binary or text?

Thanks.

Personally my preferred approach is to serialize everything as a JSON string and send it.