TcpSocket

Read/Write to/from a Tcp Socket.

Internally, two threads are started to handle the communication with the remote host.

class TcpSocket {
        constructor TcpSocket('a name');
        bool open( String host, int port );
        bool close();
        bool isConnected();

        bool hasData();
        bool writeSocket( string );
        string readSocket(); 
}

Constructor

  • Objet: TcpSocket('name')
var p = new TcpSocket('test');

.open

.open( String host , int port)

Throws an exception if the connection cannot be established.

var msg = 'test' ;
var sock = new TcpSocket('G5500');
try {    
    sock.open('127.0',4533);
    sock.writeSocket (msg + "\n");
    sock.close();
}
catch (err) {
   print('Error: ' + err);
}

Will throw TcpSocket::open() Connection to 127.0 refused

.close

Close the active connection

.close();

.isConnected

Returns true if the socket is connected, false otherwise

.hasData

.hasData();

.writeSocket

.writeSocket( string );

.readSocket

Retrieve serial buffer into text object

.readSocket();

.readBytes

Retrieve buffer into Uint8Array object

.readBytes();

.readInt16

Retrieve buffer into Uint16Array object

.readInt16();

Example 1

var s = new TcpSocket('test');
if( s.open('stackoverflow.com', 80) == false ) {
    print('Cannot open socket') ;
    exit();
}
print('Sending request');
s.writeSocket('GET /questions HTTP/1.0\n');
s.writeSocket('Host: stackoverflow.com\n');
s.writeSocket('\n\n');

sleep(100);
print('Reading response');

while( s.hasData() ) {
    var rep = s.readSocket();
    print('reply:' + rep );
}

print('Closing');
s.close();

Example 2

  • Send TCP frames to TCP listener (use nc -l -p 4533 on another shell session). 
var sock = new TcpSocket('mytcp');
sock.open('127.0.0.1',4533);

for (var a=0; a<200; a++) {
    if (sock.isConnected()) {
        sock.writeSocket (a + "\n");
        print(a,'  -- Connected : ',sock.isConnected());
        sleep(150);

    } else {
        sleep(200);
        print(a,'  -- Connected : ',sock.isConnected());
        sock.open('127.0.0.1',4533);
    }
}
Last update: November 21, 2023