XML Reference Guide

Mar 14, 2003

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Up to now, we've seen what the Semantic Web can do, we've seen microformats, and we've even seen a way to easily create them. But we haven't seen what you can actually do with them.

Ray Ozzie, who is the brains behind RSS+Shared Server Extensions, has had another thought. You can use the clipboard on your computer to copy information between applications, why can't you count the information between web pages, or even between a web page and an off-line application? Yes, you can move text easily, but what about more complex information such as objects?

After all, what good is a common format if you can't do anything with the data?

And so Ray, who works for Microsoft, and has cadres of people who can do this kind of thing, suggested that they work on a "live clipboard". In other words, he suggested that they make use of the fact that this standard information is available in order to "wire the Web". This group came up with that exact technique, and in fact has suggested several cool things you can do with it. They've also put together a simple web page, and a description of how to do it.

The description, however, is a bit cursory, and takes a bit of thinking about, so let's dissect it here.

Let's start by looking at the example. Point your browser to http://spaces.msn.com/editorial/rayozzie/demo/liveclip/liveclipsample/clipboardexample.html or click the link to open it in a new window. Notice that there are several items on the page, some of them hCards, some of them hCalendar events. Each of them has a control next to it, represented by the little scissor icon.

If you right-click the icon, it gives you the option to copy, cut, delete, or paste, just as you would in most applications. If you copy the item, and then move down to the empty control, you can click that control and paste the item. Note that you are not limited to this page. You can, in fact, copy and paste from page to page, which we'll see in a moment, when we create our own implementation of this example.

Let's start by taking a look at how the overall process works.

Essentially, this is a good example of "data binding". Text, in this case XHTML text, is converted to an object, which gets manipulated, and then is turned back into text when appropriate. To that end, you'll need to start with a script that represents the object for each microformat type you want to deal with. Microsoft provides example scripts for the hCard and hCalendar formats:

http://spaces.msn.com/editorial/rayozzie/demo/liveclip/liveclipsample/microformats/hCard.js
http://spaces.msn.com/editorial/rayozzie/demo/liveclip/liveclipsample/microformats/hCal.js

Download these scripts. Rather than referencing the live versions, which may change, you'll put them on your web server and reference the local copies from your page.

To make the copying and pasting happen, you will bind these objects and their associated actions to an object that Microsoft likes to refer to as a control, as represented by the small scissor graphic. Microsoft also provides two sample graphics for this purpose, one in its selected state, and one in its unselected state. Download these two graphics as well:

You'll also need the script that actually contains the actions available when you interact with the control. Download it here:

http://spaces.msn.com/editorial/rayozzie/demo/liveclip/liveclipsample/control/script.js

Finally, you'll need the stylesheet that goes along with all of these scripts:

http://spaces.msn.com/editorial/rayozzie/demo/liveclip/liveclipsample/control/webClipControl.css

Edit this stylesheet so that the icon url's point to the location in which you've saved your local copies of the graphics.

What we're going to do is create a page that includes a couple of hCards and a blank control into which you can paste additional hCards. The script will then create a new empty control each time you paste one, so you'll always have room for one more. You'll also have the option to delete or cut existing hCards.

Let's start by creating the actual page:

<html>
<head>

  <title>Live Clipboard demo</title>

  <link href="webClipControl.css" type="text/css" rel="stylesheet" />
  <script src="script.js" type="text/javascript"></script>
  <script src="hCard.js" type="text/javascript"></script>

  <script src="hCal.js" type="text/javascript"></script>


</head>
<body>

<h1>Demo</h1>

</body>

</html>

Here we have a basic page, along with the stylesheet and scripts. I've added the hCal script for completeness, but we won't actually be dealing with calendar events. (You'll see, however, that it wouldn't be difficult to add them.)

The next step is to set up the interface. Note that we are using Ray Ozzie's example as a guide, but you don't have to be this complicated. Start by adding a div for the contacts and their controls:

<html>
<head>
  <title>Live Clipboard demo</title>

  <link href="webClipControl.css" type="text/css" rel="stylesheet" />
  <script src="script.js" type="text/javascript"></script>
  <script src="hCard.js" type="text/javascript"></script>
  <script src="hCal.js" type="text/javascript"></script>

  <style type="text/css">
    .ControlContainer { 
         position: relative; 
         overflow:hidden; 
         float:left; 
         width:32px; 
         height:130px; 
         padding:0px;
         clear: left;
    }
  </style>

</head>
<body>

<h1>Demo</h1>

<div class="ContactContainer">

   <div class="ControlContainer" id="webClipControl1"></div>
   <div class="hcardContainer" id="contactHcard1"></div>

   <div class="ControlContainer" id="webClipControl2"></div>

   <div class="hcardContainer" id="contactHcard2"></div>

</div>

</body>
</html>

We're going to start by adding just two contacts, so we'll create two sets of divs. The first is the webClipControl, and the second is the contactHcard div. Notice that each of these divs has a unique ID value. We're going to be binding objects to them, so we need a way to refer to them uniquely.

If you pull up the page now, you won't see much of anything. This is because much of the presentation, including the control graphics, will be handled using the stylesheet, and the various styles will get added dynamically by the code. Again, you don't have to do it this way. You could just as easily add a graphic right now and bind to it and so on, but to use the example scripts, this is the way it has to be.

Next we'll go ahead and create the actual hCard instances. We'll do that by creating instances of the hCard class we've already defined (by virtue of the fact that we included the hCard.js script):

...
<h1>Demo</h1>

<div class="ContactContainer">
<div class="ControlContainer" id="webClipControl1"></div>
<div class="hcardContainer" id="contactHcard1"></div>

<div class="ControlContainer" id="webClipControl2"></div>
<div class="hcardContainer" id="contactHcard2"></div>

</div>

  <script type="text/javascript">


    var hCard1 = new HCard("Nicholas", "Chase", "lotsaspam@nicholaschase.com", 
                          "212 555 1212", null, null, null, null, null, 
                           null, null, "73 Main St.", "New York", "NY", 
                          "10101","USA");

    var hCard2 = new HCard();


  </script>

</body>
</html>

Again, the hCard object is defined in the hCard.js script we downloaded from the sample files. You could just as easily create your own script, but if you want it to interoperate with other implementations, (in other words, if you want to copy and paste data between web pages) you'll need to make sure it follows the format and specification expected by the main control script.

Also note that here we are simply defining the objects by hardcoding them, but we could just as easily have created a form on the page to accept all of the different parameters. In this case, I've added only my name and a few pieces of information.

The second hCard instance is simply an empty instance we can populate later. In other words, we can take this empty object and "paste" data into it. To do that, we will need to bind it to specific actions:

...
<div class="ContactContainer">
<div class="ControlContainer" id="webClipControl1"></div>

<div class="hcardContainer" id="contactHcard1"></div>

<div class="ControlContainer" id="webClipControl2"></div>
<div class="hcardContainer" id="contactHcard2"></div>

</div>

  <script type="text/javascript">

    function MicroFormatObjectBinding( displayDiv, 
                                       microFormatObject, 
                                       inactiveStyleClassName, 
                                       activeStyleClassName)
    {

        var webClip;
        var self = this;
          
        this.updateDisplayAndWebClipData = function()
        {
            webClip = new LiveClipboardContent();
            displayDiv.innerHTML = microFormatObject.HTML;
            webClip.data.formats[0] = new DataFormat();
            webClip.data.formats[0].type = microFormatObject.formatType;
            webClip.data.formats[0].contentType = "application/xhtml+xml";
            webClip.data.formats[0].items = new Array(1);
            webClip.data.formats[0].items[0] = new DataItem();
            webClip.data.formats[0].items[0].xmlData = microFormatObject.xmlData;
        }
         
        this.onActive = function()
        {
            if (displayDiv.childNodes[0] && 
                  (displayDiv.childNodes[0].className == microFormatObject.formatRootClassName))
                displayDiv.className = activeStyleClassName;
        }
        
        this.onInactive = function()
        {
            displayDiv.className = inactiveStyleClassName;
        }
         
        this.onCopy = function()
        {     
            return webClip;
        }
        
        this.onPaste = function(clipData)
        {

            for (var i = 0; i < clipData.data.formats.length; i++)
            {
                if ((clipData.data.formats[i].contentType = "application/xhtml+xml") 
                       && (clipData.data.formats[i].type == microFormatObject.formatType) 
                       && (clipData.data.formats[i].items.length > 0) 
                       && (clipData.data.formats[i].items[0].xmlData))
                {
                    microFormatObject.initFromXml(clipData.data.formats[i].items[0].xmlData);
                    self.updateDisplayAndWebClipData();
                        
                    // For now, just look at the first microFormatObject found.
                    return;
                }
            }
            
            // No matching formats found -- this could mean cut/delete -- so clear the associated data.
            microFormatObject.clearProps();
            self.updateDisplayAndWebClipData();
        }            
        
        self.updateDisplayAndWebClipData();
    }

    var hCard1 = new HCard("Nicholas", "Chase", "lotsaspam@nicholaschase.com", 
                          "212 555 1212", null, null, null, null, null, 
                           null, null, "73 Main St.", "New York", "NY", 
                          "10101","USA");

    var hCard2 = new HCard();


  </script>

</body>
</html>

Now, this is straight from the example, and is probably more than you need, but before you agonize over it, just understand that it defines various actions, and what should be done when those events occur, such as when the control becomes active or inactive, or when the user pastes data into the control. Also, in the updateDisplayAndWebClipData() function, you can see how the microformat object (in this case the hCard) and its various attributes can be used.

This function takes as arguments the div that will display the hCard, the hCard object to display, and class names to use for active and inactive states. This means that you can create your own styles, and simply specify them in a local stylesheet. For now, however, we'll use the provided stylesheet.

Now let's look at creating actual bindings:

...
    var hCard1 = new HCard("Nicholas", "Chase", "lotsaspam@nicholaschase.com", 
                          "212 555 1212", null, null, null, null, null, 
                           null, null, "73 Main St.", "New York", "NY", 
                          "10101","USA");

    var contactBinding1 = new MicroFormatObjectBinding(
                          document.getElementById("contactHcard1"), 
                          hCard1, 
                          "hcardContainer", 
                          "hcardContainer selected");

    var clipBoardControl1 = new WebClip(
                          document.getElementById("webClipControl1"), 
                          contactBinding1.onCopy, 
                          contactBinding1.onPaste, 
                          contactBinding1.onActive, 
                          contactBinding1.onInactive);

    var hCard2 = new HCard();

    var contactBinding2 = new MicroFormatObjectBinding(
                                   document.getElementById("contactHcard2"), 
                                   hCard2, 
                                   "hcardContainer", 
                                   "hcardContainer selected");

    var clipBoardControl2 = new WebClip(
                                   document.getElementById("webClipControl2"), 
                                   contactBinding2.onCopy, 
                                   contactBinding2.onPaste, 
                                   contactBinding2.onActive, 
                                   contactBinding2.onInactive);

  </script>

</body>
</html>

We start by creating a binding object, which includes the hCard to display, and where to display it. Once we have that binding, we then create the actual control. To create the control, we pass the div in which the control lives, (and which actually acts as the control in this case). It also contains information on what functions to call when the user copies, pastes, activates, and inactivates the control.

Now we can see how this looks when we execute it:

Notice that the first control has hCard information associated with it, but the second does not. That's because the hCard object was empty. Now right-click the top icon and choose Copy>. Then right-click the bottom icon and click Paste. Notice that browser pastes the data into the second control:

You can even copy an hCard from this page to Ray Ozzie's sample page:

Basically, when you choose to "Copy", the information that gets added to your clipboard is all of the microformat data, which is just text. But just as you can copy and paste text from one page to another, you can copy and paste text that includes markup specifying a microformat object. So when you copy on this page and paste on Ray Ozzie's page, it's really just text moving around. But the text has enough information to re-create the object.

We can also extend this example so that we are not limited to how many examples with it on the page. Consider this example:

...
<body>

<h1>Demo</h1>

<div class="ContactContainer" id="Contacts">

</div>

  <script type="text/javascript">


    function MicroFormatObjectBinding( displayDiv, 
                                       microFormatObject, 
                                       inactiveStyleClassName, 
                                       activeStyleClassName)
    {
...
    }

    var hCards = new Array();
    var contactBindings = new Array();
    var clipBoardControls = new Array();


    hCards[0] = new HCard("Nicholas", "Chase", "lotsaspam@nicholaschase.com", 
                                 "212 555 1212", null, null, null, null, null, 
                                 null, null, "73 Main St.", "New York", "NY", 
                                 "10101","USA");

    hCards[1] = new HCard("Sarah", "Chase", "lotsaspam@nicholaschase.com", 
                                 "212 555 1212", null, null, null, null, null, 
                                 null, null, "73 Main St.", "New York", "NY", 
                                 "10101","USA");


  </script>

</body>
</html>

In this case, we start with an empty Contacts div, and rather than specifying individual hCards and bindings, we create three arrays to hold them. We can then specify to hCard objects to start with.

Now we need a script that sets up the controls in the contact on the page:

...
<div class="ContactContainer" id="Contacts">

</div>

  <script type="text/javascript">

    function createNewContact(thisCard){

        var thisGroupNumber = clipBoardControls.length;
        var contactDivName = "contactHcard"+thisGroupNumber;
        var webClipDivName = "webClipControl"+thisGroupNumber;

        var newControlDiv = document.createElement("div");
        newControlDiv.setAttribute("class", "ControlContainer");
        newControlDiv.setAttribute("id", webClipDivName);

        var newDisplayDiv = document.createElement("div");
        newDisplayDiv.setAttribute("class", "hcardContainer");
        newDisplayDiv.setAttribute("id", contactDivName);

        document.getElementById("Contacts").appendChild(newControlDiv);
        document.getElementById("Contacts").appendChild(newDisplayDiv);

        contactBindings[thisGroupNumber] = new MicroFormatObjectBinding(
                                    document.getElementById(contactDivName), 
                                    thisCard, 
                                    "hcardContainer", 
                                    "hcardContainer selected");
        clipBoardControls[thisGroupNumber] = new WebClip(
                                    document.getElementById(webClipDivName), 
                                    contactBindings[thisGroupNumber].onCopy, 
                                    contactBindings[thisGroupNumber].onPaste, 
                                    contactBindings[thisGroupNumber].onActive, 
                                    contactBindings[thisGroupNumber].onInactive);
 
    }


    function createEmptyContact(){

        var thisGroupNumber = clipBoardControls.length;
        hCards[thisGroupNumber] = new HCard();
        createNewContact(hCards[thisGroupNumber]);

    }

    function MicroFormatObjectBinding( displayDiv, 
                                       microFormatObject, 
                                       inactiveStyleClassName, 
                                       activeStyleClassName)
    {
...

In essence, to createNewContact() function simply creates the divs that we had previously specified by hardcoding them, right down to unique ID values. It starts with the knowledge of how many controls have already been added to the array, so the first one is number zero, the second is number one, and so on. Once it creates the divs, it adds them to the page. From there, we can create the new bindings and controls just as before, but again, we are referenceing an array of objects rather than a hardcoded object.

We can also easily create an empty control by simply calling createEmptyContact(), which calls createNewContact() with an empty hCard.

Finally, we need to go ahead and find the hCard to their various controls:

...
    hCards[0] = new HCard("Nicholas", "Chase", "lotsaspam@nicholaschase.com", 
                                 "212 555 1212", null, null, null, null, null, 
                                 null, null, "73 Main St.", "New York", "NY", 
                                 "10101","USA");

    hCards[1] = new HCard("Sarah", "Chase", "lotsaspam@nicholaschase.com", 
                                 "212 555 1212", null, null, null, null, null, 
                                 null, null, "73 Main St.", "New York", "NY", 
                                 "10101","USA");


    for (i=0; i<hCards.length; i++){
        createNewContact(hCards[i]);
    }

    createEmptyContact();

  </script>

</body>
</html>

It's a simple process of looking through each of the cards in the hCards array and creating a new contact for it. When we're done, we create an empty contact, so that additional items can be added. We can also have the browser add an empty contact when you paste an hCard into the list:

...
   this.onPaste = function(clipData)
   {

       for (var i = 0; i < clipData.data.formats.length; i++)
       {
           if ((clipData.data.formats[i].contentType = "application/xhtml+xml") 
                  && (clipData.data.formats[i].type == microFormatObject.formatType) 
                  && (clipData.data.formats[i].items.length > 0) 
                  && (clipData.data.formats[i].items[0].xmlData))
           {
               microFormatObject.initFromXml(clipData.data.formats[i].items[0].xmlData);
               self.updateDisplayAndWebClipData();


               createEmptyContact();

               // For now, just look at the first microFormatObject found.
               return;
           }
       }
            
       // No matching formats found -- this could mean cut/delete -- so clear the associated data.
       microFormatObject.clearProps();
       self.updateDisplayAndWebClipData();
   }            
...

From here you should be able to create as many contacts as you want, and to copy and paste them to and from anywhere you like, as long as the source and destination implements Live Clipboard.

This is really just a simple idea of what Live Clipboard and related technologies can do. In fact, several of the screencasts Microsoft put up to demonstrate this include discussion of copying and pasting RSS feeds. You can also see hints of that in the scripts. Of course, you would have to have your own object to bind to in order to make that work, but you can create that yourself, if a sample doesn't come around fast enough for you.

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