How-to create self-updating WRT widgets
Article Metadata
Compatibility
Platform(s): S60 3rd Edition FP2
Article
Created: forum-mrkt
(03 Oct 2007)
Last edited: hamishwillee
(12 Oct 2012)
Contents |
Theory
For Symbian Web Runtime the easiest way to do self-update is to have application to do version checking by itself. A variable in the widget's bundle can indicate current version that can be checked against server interface. This approach doesn't require any extensions or platform tricks, it is pure JavaScript implementation.
Example setup
Following example assumes that you have script running on server side at http://myexample.versionservice.com:8888. Server responds to version request with XML document including version tag. This example can be easily extended e.g. to include update url in version response message.
Example code
/*
* version server url, and current version
*/
var versionURL = "http://myexample.versionservice.com:8888";
var currentVersion = 1;
var reqV = null;
/*
* called e.g. during app startup or once a day
*/
function checkForUpdate()
{
/*
* asynch XHR to server url
*/
reqV = new XMLHttpRequest();
reqV.onreadystatechange = checkVersion;
reqV.open("GET", versionURL, true);
reqV.send(null);
document.getElementById("updateDIV").innerHTML = "checking for updates";
}
/*
* parse response and check version
*/
function checkVersion()
{
if (reqV.readyState == 4)
{
if (reqV.status == 200)
{
/*
* little overhead here, one could use also string for version info
*/
var newVersion = reqV.responseText;
if (currentVersion != newVersion)
{
document.getElementById("updateDIV").innerHTML =
"<a href=\"http://www.taika.org/~jario/newversion.wgz\">
Download new version</a>";
}
else
{
document.getElementById("updateDIV").innerHTML =
"No new versions available";
}
}
else
{
alert( "connection error" );
}
}
}
Example main HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<script type='text/javascript' src="selfupdate.js"></script>
</head>
<body onload="checkForUpdate();">
<div id="updateDIV"></div>
</body>
</html>
18 Sep
2009
A software needs some improvement and to achieve the same it needs a kind of update feature. The update feature should interact with the outer resource and then should decide weather to update the software or not.
In the case of WRT Widgets the tasks become quite simple as they are frequently connected withe web. The article is an excellent example of achieving the auto updating task of web, the code explains clearly two functions which checks for updates and versions if new is available it will download that and replace the existing one.
This is an article of Basic level beginners can easily go through it.