XML Example

Here is an example of a XML web page update written in the script language. This web page displays the value of analog input (AD). When first opened, a complete AD web page is generated by the Embedded web server. Later, when you enable the periodic update of the page, this page is updated with Java Script function updateMultiple(). This function is in xml_http.js file.

• The script file ad.cgx contains the following:

  t <form>
  t <text>
  t <id>ad_value</id>
  c x<value>0x%03X</value>
  t </text>
  t </form>
  .
  

• The script interpreter processess this file and generates the following response:

  <form><text><id>ad_value</id><value>0x06A</value></text></form>
  

  The XML response does not contain any spaces or CR-LF characters between the XML tags.
• The Java Script function periodicUpdateAd() activates the periodic timeouts for the page update. This function is specific for AD page module and is included in ad.cgi script file:

  function periodicUpdateAd() {
    if(document.getElementById("adChkBox").checked == true) {
      updateMultiple(formUpdate,plotADGraph);
      ad_elTime = setTimeout(periodicUpdateAd, formUpdate.period);
    }
    else
      clearTimeout(ad_elTime);
  }
  

• The update interval and url are defined in the formUpdate object. When update interval expires, an xml response is requested from the url specified in this java object.

  var formUpdate = new periodicObj("ad.cgx", 500);
  

• The actual update of the analog bar and AD values on the web page is done by the java function plotADGraph():

  function plotADGraph() {
    adVal = document.getElementById("ad_value").value;
    numVal = parseInt(adVal, 16);
    voltsVal = (3.3*numVal)/1024;
    tableSize = (numVal*100/1024);
    document.getElementById("ad_table").style.width = (tableSize + '%');
    document.getElementById("ad_volts").value = (voltsVal.toFixed(3) + ' V');
  }
  

  This function is called as a call-back function from the updateMultiple() java function.

• The XML script files use the reserved filename extension cgx. Using the cgx file extension for XML script files is mandatory for the Web Server script interpreter to recognize and process the XML script files.
• There must be no spaces or CR-LF characters between XML tags, or some web browsers might have problems when parsing the XML response.
• The script line length is limited to 120 characters.