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Hello, World! - Sending Message via WebSocket

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  • Hello, World! - Sending Message via WebSocket


    Tutorial Video



    Hardware
    • PHPoC Blue (+ USB WLAN) or PHPoC Black (+ Ethernet cable)
    • Micro USB to USB Cable (to upload source code to PHPoC Device)


    Quick Steps

    Source code of this example is a part of PHPoC Support Packet (PSP). You need to:
    • Download PHPoC Support Package.
    • Upload example\p4s\04.html5_text\00.hello to PHPoC Blue/Black.
    • Configure network parameters (e.g. WiFi SSID, password, IP address ...).
    • Click "Run" button on PHPoC Debugger.
    • Access webpage on PHPoC using Web Browser on your PC or smart phone (See How To).
    If you use PHPoC for the first time, see How To Use PSP.


    Source Code

    Source files includes:
    • init.php: this file is run when PHPoC system is powered or reset. It is used to specify which file is run is system loop.
    • task0.php: this file is run in system loop of PHPoC devices. It acts as WebSocket server and also interacts with .
    • index.php: this file contains source code of web page.It is only run in response to request from Web Browser. It contains webpage (user interface) and acts WebSocket client.

    init.php

    This file is run when PHPoC system is powered or reset. It is used to specify that task0.php is run is system loop.
    PHP Code:
    <?php

    system
    ("php task0.php");

    ?>



    task0.php

    [Full Code]
    PHP Code:
    <?php

    if(_SERVER("REQUEST_METHOD"))
     exit; 
    // avoid php execution via http request

    include "/lib/sd_340.php";
    include 
    "/lib/sn_tcp_ws.php";

    ws_setup(0"WebConsole""text.phpoc");

    while(
    1)
    {
     if(
    ws_state(0) == TCP_CONNECTED)
     {
      
    ws_write(0"hello, world!\r\n");

      
    sleep(1);
     }
    }

    ?>



    [Explanation]

    Source code of this file does:
    • Setup and initialize WebSocket.
    In infinite loop:
    • Send 'hello, world!' to Web Browser via WebSocket.

    index.php

    [Full Code]
    PHP Code:
    <html>
    <head>
    <title>PHPoC / <?echo system("uname -i")?></title>
    <meta name="viewport" content="width=device-width, initial-scale=0.7">
    <style>
    body { text-align:center; }
    textarea { width:400px; height:400px; padding:10px; font-family:courier; font-size:14px; }
     </style>
    <script>
    var ws;
    var wc_max_len = 32768;
    function ws_onopen()
    {
     document.getElementById("ws_state").innerHTML = "OPEN";
     document.getElementById("wc_conn").innerHTML = "Disconnect";
    }
    function ws_onclose()
    {
     document.getElementById("ws_state").innerHTML = "CLOSED";
     document.getElementById("wc_conn").innerHTML = "Connect";

     ws.onopen = null;
     ws.onclose = null;
     ws.onmessage = null;
     ws = null;
    }
    function wc_onclick()
    {
     if(ws == null)
     {
      ws = new WebSocket("ws://<?echo _SERVER("HTTP_HOST")?>/WebConsole", "text.phpoc");
      document.getElementById("ws_state").innerHTML = "CONNECTING";

      ws.onopen = ws_onopen;
      ws.onclose = ws_onclose;
      ws.onmessage = ws_onmessage;
     }
     else
      ws.close();
    }
    function ws_onmessage(e_msg)
    {
     e_msg = e_msg || window.event; // MessageEvent

     var wc_text = document.getElementById("wc_text");
     var len = wc_text.value.length;

     if(len > (wc_max_len + wc_max_len / 10))
      wc_text.innerHTML = wc_text.value.substring(wc_max_len / 10);

     wc_text.scrollTop = wc_text.scrollHeight;
     wc_text.innerHTML += e_msg.data;
    }
    function wc_clear()
    {
     document.getElementById("wc_text").innerHTML = "";
    }
    </script>
    </head>
    <body>

    <h2>
    <p>
    Web Console : <span id="ws_state">CLOSED</span><br>
    </p>
    <textarea id="wc_text" readonly="readonly"></textarea><br>
    <button id="wc_conn" type="button" onclick="wc_onclick();">Connect</button>
    <button id="wc_clear" type="button" onclick="wc_clear();">Clear</button>
    </h2>

    </body>
    </html>



    [Explanation]

    Source code of index.php file is composed of HTML, CSS, JavaScript and PHPoC code.

    PHPoC code is interpreted on on PHPoC device.

    PHPoC code may add/update the content of HTML, CSS or JavaScript code. Once PHPoC code is interpreted in PHPoC, the remaining code is client-side code and it is returned to Web Browser. Web Browser receives this code and interpret it to display the webpage.
    • HTML: describes the structure of Web pages
    • CSS: describes how HTML elements are to be displayed
    • JavaScript: This code:
      - Receive data ('hello, world!' of ) from PHPoC devices via WebSocket,
      - Display 'hello, world!' on webpage
    For detail explanation, see How to Monitor Sensors/Devices via WebSocket




    See Also

    Other Resources
    Last edited by support; 12-03-2018, 10:30 AM.
      Posting comments is disabled.

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