Any online shop (hereafter 'merchant') in its work faces the necessity of integration with a great variety of third-party services such as credit card processing or a third-party verification phone service (TPV) e.g. ProveOut.com. The TPV's working principle is simple: the Merchant provides their ID and the client's phone number to the TPV service which dials the given phone number. At this time the client has to enter a certain three- or four-digit PIN code or confirm their order by voice.

Until AJAX Technology was developed the standard approach consisted of the following:

• The merchant placed a special HTML form on their webpage, e.g.:

  
  <form name="demo_form" action="TPV_URL" method="post">
          <INPUT type="hidden" name="merchant_shop_id" value="123456">
          <INPUT type="hidden" name="customer_phone_number" value="1234567890">
          <INPUT type="submit" name="submit" value="Call">
  </form>
  
  

• By clicking the 'Call' button the client moved from the merchant's site to the TPV site.
• The TPV dialled the provided client's phone number.
• Depending on the call's result the TPV redirected the client to the relevant merchant's URL.

In practice the application of this method has revealed several shortcomings:

• A client can leave the merchant's site if an error has occurred in the merchant's HTML form settings or if something is wrong on the TPV site.
• When a merchant uses a standard shopping cart software and their webmaster has little experience in programming, problems in the HTML form implementation in the existent site code occur quite often. Also, there may be errors in making additional pages that clients access after passing the TPV procedure.

The application of AJAX Technology eases much of the problems of the described scheme as there is no need to redirect the client to the TPV site. A new scheme looks like this:

• The merchant places a small Javascript code on their webpage:

  
  <script type="text/javascript">
  <!-- merchant_id = "123456";customer_phone_number="1234567890";
  //-->></script>
  <script type="text/javascript" src="TPV_URL"></script>
  
  

• The Javascript file placed by the TPV_URL link outputs a fragment of a webpage containing instructions and a 'Call' button. After clicking 'Call' button a verification call is initiated - its results are then dynamically displayed in the same page's fragment. The data exchange between the client's browser and the TPV server is processed with the help of the XMLHttpRequest object.

The advantages of this scheme are obvious:

• The client does not need to redirected to a TPV site and back.
• Very basic HTML knowledge is enough to implement a the small fragment of Javascript code in an existent page's HTML code. Additional pages for call results processing aren't necessary any more.

• The TPV service can update its working scheme and add new features without changing the code on the merchant's side.

AJAX Technology has practically no disadvantages except incompatibility with older browsers. AJAX also demands Javascript support and ActiveX support (for Microsoft's browsers). But soon these things will pass into history. For example, Microsoft recently announced that its new Internet Explorer 7.0 browser will have the XMLHttpRequest object library built in and therefore ActiveX support will no longer be needed.

Google Inc. actively uses AJAX in its popular services such as Gmail and Google Adsense.