<div class="intro">
<p>In this example, the Uploader is used to send multiple images or videos to the server and monitor
   their upload progress with individual counters. If the Uploader is used in a browser with HTML5
   support, it is progressively enhanced to enable dragging-and-dropping files into the browser window.
   Along with each file, this example also submits an additional POST variable (the file's name).
   Once each upload completes, the server sends the received file name POST variable back, along with a time
   stamp, and the example displays them next to the file.</p>
   
<p><strong>Please note:</strong> This example will not work when run from a local filesystem because of security restrictions in the transport protocols used. If you’d like to run this example locally, set up a local web server and launch it from there.</p>

<p><strong>Also note:</strong> You will need compile and host your own <code>flashuploader.swf</code> file to enable Flash mode which is needed for IE <= 9. Necessary source files are available in the <a href="https://github.com/yui/yui3-swfs">yui3-swfs</a> repository.</p>

<p><strong>Also note:</strong> The uploader is not supported on iOS devices (iPhone and iPad), because they lack file upload capability. This example provides a graceful degradation message for all such systems.</p>

<p><strong>Also note:</strong> The backend script used in these examples does not store any information it receives. Nevertheless, do not submit any sensitive or private data and keep
your tests to a few small files to avoid overloading the system.</p>
</div>

<div class="example yui3-skin-sam">
    {{>uploader-data-source}}
</div>

<h2>Sending and Retrieving Data from the Server</h2>
<p>This example is based on the <a href="uploader-dd.html">Uploader with HTML5 Drag-and-Drop Support</a>, but adds custom POST variables along with each file upload,
   and retrieves and displays data received from the server in response to each file upload.</p>

<p>To send additional POST variables along with files, we populate the `postVarsPerFile` attribute when files are selected:

```
uploader.after("fileselect", function (event) {

   ...
            
   var perFileVars = {};
   
   Y.each(fileList, function (fileInstance) {
       fileTable.append("<tr id='" + fileInstance.get("id") + "_row" + "'>" + 
                             "<td class='filename'>" + fileInstance.get("name") + "</td>" + 
                             "<td class='filesize'>" + fileInstance.get("size") + "</td>" + 
                             "<td class='percentdone'>Hasn't started yet</td>" +
                             "<td class='serverdata'>&nbsp;</td>"); 
  
       perFileVars[fileInstance.get("id")] = {filename: fileInstance.get("name")};
   });
   
   uploader.set("postVarsPerFile", Y.merge(uploader.get("postVarsPerFile"), perFileVars));
});
```

<p>When uploads complete, we can retrieve and display the data received from the server (in this case, the `filename` POST variable that we transmitted,
   along with the server timestamp):

```
uploader.on("uploadcomplete", function (event) {

    ...

    fileRow.one(".serverdata").setHTML(event.data);
});

```

<h2>Full Source Code For this Example</h2>

```
{{>uploader-data-source}}
```

