Archive for August, 2007
PHP library for Microsoft AJAX
By Justin Silverton
Microsoft has released their AJAX library package for non-windows systems which contains a complete set of client JavaScript components that are included in the full ASP.NET AJAX installation. Developers over at Codeplex have developed a library that allows you to integrate your PHP applications with this package.
requirements
- PHP 5.2 — 5.2 is required for json_encode/json_decode; For earlier versions, you will need to install php-json
How to install
- Download the PHP library from codeplex here
- Download the Microsoft AJAX Library here
- After extracting both of these, place all the files from the Microsoft Ajax library in a directory called “MicrosoftAjaxLibrary”
Example
The following is a simple example that demonstrates a simple ajax transmission using the microsoft libraries.
(hello.htm)
<html>
<head>
<title>Hello, World!</title>
<script type="text/javascript" src="../../MicrosoftAjaxLibrary/MicrosoftAjax.js"></script>
<script type="text/javascript" src="HelloService.php/js"></script>
</head>
<body>
Name: <input id="name" type="text" /> <input type="button" value="Say Hello" onclick="button_click(); return false;" />
<br />
Response from server: <span id="response"></span>
</body>
<script type="text/javascript">
function button_click() {
HelloService.SayHello($get('name').value, function (result) { $get('response').innerHTML = result; });
}
</script>
</html>
(HelloService.php)
<?php
require_once '../../dist/MSAjaxService.php';
class HelloService extends MSAjaxService
{
function SayHello($name)
{
return "Hello, " . $name . "!";
}
}
$h = new HelloService();
$h->ProcessRequest();
?>
Using Ajax across multiple domains
By Justin Silverton
XMLHttpRequest, the main component behind AJAX, does not automatically work across multiple domains. This means that you cannot make a request to an ovject on a domain that is different from the web page’s domain. There is an easy solution to this issue: apache’s mod_rewrite module.
Example
function getXMLHttpObject()
{
if (window.XMLHTTPRequest)
return new XMLHttpRequest();
else if (window.ActiveXObject)
return new ActiveXObject("Microsoft.XMLHTTP");
else
return null;
}
function handleHTTPResponse()
{
if (http.readyState == 4) {
results = http.responseText;
}
}
var http = getXMLHttpObject();
http.open("POST"."http://www.yahoo.com/service");
http.onreadystatechange = handleHttpResponse;
The above example will fail with both Firefox and Internet Explorer (unless you are running it on a web page located on the yahoo domain). There are other ways to allow cross site ajax. Within Internet Exporer, the default security settings can be changed or a host can be added to the “trusted hosts” list. Firefox, on the other hand, has a concept called signed scripts. Both of these methods will not work for most websites on the Internet. This is because it would involve every user coming to your site adding your page to their trusted host list.
Apache setup
- Install apache with both mod_rewrite and proxy enabled.
- Create the following rule: RewriteRule ^/yahoo_proxy http://www.yahoo.com/service [P]
Note: The [P] indicates a pass-through proxy.
Replace the above line: (http.open("POST"."http://www.yahoo.com/service")) with
http.open("POST"."http://your_host/yahoo_proxy") and a connection will be made to the yahoo domains through your apache server while not violating the security restrictions of IE or Firefox.
Secret Internet Explorer behaviors
By Justin Silverton
Many people don’t realize that there is a way to store up to 100K (1mb per domain) of data within Internet Explorer (supported by 5.5 and above).
These behaviors can be used to preserve information in the browser’s history, in favorites, in an XML store, or directly within a Web page saved to disk. When a user returns to a persisted page, the state of the page can be restored. By allowing information to safely reside on the client, fewer server transactions are required. Custom start pages and Web applications prosper because information can continue to exist without the paternal support of the server, or repeated server queries. A Web page can remain interactive to a degree, after the connection with the host has been severed, by persisting required information on the client.
Code Example
Below is an code example of how to use these behaviors. After typing some text into the box and clicking save, you will now be able to come back to this page and click load, and it will be loaded from the the IE internal persistence store.
<STYLE>
.storeuserData {behavior:url(#default#userData);}
</STYLE>
<SCRIPT>
function fnSaveInput(){
var oPersist=oPersistForm.oPersistInput;
oPersist.setAttribute("sPersist",oPersist.value);
oPersist.save("oXMLBranch");
}
function fnLoadInput(){
var oPersist=oPersistForm.oPersistInput;
oPersist.load("oXMLBranch");
oPersist.value=oPersist.getAttribute("sPersist");
}
</SCRIPT>
<FORM ID="oPersistForm">
<INPUT CLASS="storeuserData" TYPE="text" ID="oPersistInput">
<table>
<td><INPUT TYPE="button" VALUE="Load" onclick="fnLoadInput()"></td>
<td><INPUT TYPE="button" VALUE="Save" onclick="fnSaveInput()"></td>
</table>
</FORM>