Learning WCF

Creating a Dual Purpose Login Page

The code sample for this appendix includes a login page that uses the ASP.NET Login control for traditional login and the <object> tag for those who have already associated their information cards with their account. One of the challenges with this is making sure that the <object> tag is only invoked when the user clicks the CardSpace login button. Since we can’t have two active <form> tags in an ASP.NET page, I had to learn a little bit more about <object> tags, how they are instantiated, and how to control that instantiation with javascript.

First, I placed the <object> tag declaration in the header section of the HTML page. I also had to use the declare attribute of the tag to indicate this was only a declaration so that the CardSpace object would not be instantiated until it is referenced by the CardSpace submit button:

<object declare id="informationCard"
type="application/x-informationCard" name="informationCard" >
...
</object>

Next, I created a javascript function, SelectInformationCard( ), that would instantiate the CardSpace object and put the value it returns into a hidden text field:

<script type="text/javascript" language="javascript">
  function SelectInformationCard( )
  {
    var infoCardObject =document.getElementById("informationCards");
    var hiddenToken = document.getElementById("hiddenXmlToken");
    hiddenToken.value = infoCardObject.value;
  }
</script>

Within the <form> tag, I arranged the Login control and my CardSpace image button, along ...