There is one problem with most of the current implementations of Ajax: it has one dependency, and that is the XmlHttpRequest object. Most modern browser, like Firefox, have inbuilt support for this object, but older browsers, like Internet Explorer 6, don't have native support for this object. Luckily, IE 6 does support it, but it's built in as an ActiveX control, which means your visitors get an ugly warning message about the possible danger of an ActiveX control, or in some cases it just doesn't work at all.
In this tutorial, I will show you how to use Ajax without even having to use the XmlHttpRequest object.
The basics
If we can't use the XmlHttpRequest object, we must find some other way to include content from another page, without having to resort to other objects or non-standard things. A great candidate for this would be the <script> tag, which is used to include external JavaScript files. What if, instead of using a regular JS file, we point that tag to a PHP file, which outputs JavaScript. A PHP file which looks something like this:
<?php
$html = '<b>This content came from our Ajax Engine</b>';
?>
div = document.getElementById('contentdiv');
div.innerHTML = '<?php echo $html; ?>';
When this file is used referenced in a script tag, it will try to set the innerHTML of a div with ID 'contentdiv'. But there's one problem; this file shouldn't be included when the page loads, but only when a button is clicked or some other action. To do this, we must somehow dynamically add a new script tag, which is possible using JavaScript. Something like the following would do the trick:
// Get base url
url = document.location.href;
xend = url.lastIndexOf("/") + 1;
var base_url = url.substring(0, xend);
function ajax_do (url) {
// Does URL begin with http?
if (url.substring(0, 4) != 'http') {
url = base_url + url;
}
// Create new JS element
var jsel = document.createElement('SCRIPT');
jsel.type = 'text/javascript';
jsel.src = url;
// Append JS element (therefore executing the 'AJAX' call)
document.body.appendChild (jsel);
}
This code first gets the current directory of the url, so we have a base url. The 'ajax_do' function is the thing that does all the work. It first checks whether the url passed to the function points to another domain, or is a relative file.
It then creates a new script element, using the createElement() function. After that it sets the src attribute of the script element, and adds the script element to the body, effectively 'loading' the file that is referenced by the script element.
All we need now is a simple page that triggers the Ajax call, i.e.
<html>
<head>
<title>Demo 1 - The Basic's</title>
<script type="text/javascript" src="engine.js"></script>
</head>
<body>
<div id="contentdiv">
</div>
<input type="button" onclick="ajax_do ('page1.php');" value="Get content" />
</body>
</html>
Tuesday, October 7, 2008
Tuesday, September 30, 2008
$_SERVER -- $HTTP_SERVER_VARS [deprecated] — Server and execution environment information
$_SERVER is an array containing information such as headers, paths, and script locations. The entries in this array are created by the web server. There is no guarantee that every web server will provide any of these; servers may omit some, or provide others not listed here. That said, a large number of these variables are accounted for in the » CGI 1.1 specification, so you should be able to expect those.
$HTTP_SERVER_VARS contains the same initial information, but is not a superglobal. (Note that $HTTP_SERVER_VARS and $_SERVER are different variables and that PHP handles them as such)
You may or may not find any of the following elements in $_SERVER. Note that few, if any, of these will be available (or indeed have any meaning) if running PHP on the command line.
'PHP_SELF'
The filename of the currently executing script, relative to the document root. For instance, $_SERVER['PHP_SELF'] in a script at the address http://example.com/test.php/foo.bar would be /test.php/foo.bar. The __FILE__ constant contains the full path and filename of the current (i.e. included) file. If PHP is running as a command-line processor this variable contains the script name since PHP 4.3.0. Previously it was not available.
'argv'
Array of arguments passed to the script. When the script is run on the command line, this gives C-style access to the command line parameters. When called via the GET method, this will contain the query string.
'argc'
Contains the number of command line parameters passed to the script (if run on the command line).
'GATEWAY_INTERFACE'
What revision of the CGI specification the server is using; i.e. 'CGI/1.1'.
'SERVER_ADDR'
The IP address of the server under which the current script is executing.
'SERVER_NAME'
The name of the server host under which the current script is executing. If the script is running on a virtual host, this will be the value defined for that virtual host.
'SERVER_SOFTWARE'
Server identification string, given in the headers when responding to requests.
'SERVER_PROTOCOL'
Name and revision of the information protocol via which the page was requested; i.e. 'HTTP/1.0';
'REQUEST_METHOD'
Which request method was used to access the page; i.e. 'GET', 'HEAD', 'POST', 'PUT'.
Note: PHP script is terminated after sending headers (it means after producing any output without output buffering) if the request method was HEAD.
'REQUEST_TIME'
The timestamp of the start of the request. Available since PHP 5.1.0.
'QUERY_STRING'
The query string, if any, via which the page was accessed.
'DOCUMENT_ROOT'
The document root directory under which the current script is executing, as defined in the server's configuration file.
'HTTP_ACCEPT'
Contents of the Accept: header from the current request, if there is one.
'HTTP_ACCEPT_CHARSET'
Contents of the Accept-Charset: header from the current request, if there is one. Example: 'iso-8859-1,*,utf-8'.
'HTTP_ACCEPT_ENCODING'
Contents of the Accept-Encoding: header from the current request, if there is one. Example: 'gzip'.
'HTTP_ACCEPT_LANGUAGE'
Contents of the Accept-Language: header from the current request, if there is one. Example: 'en'.
'HTTP_CONNECTION'
Contents of the Connection: header from the current request, if there is one. Example: 'Keep-Alive'.
'HTTP_HOST'
Contents of the Host: header from the current request, if there is one.
'HTTP_REFERER'
The address of the page (if any) which referred the user agent to the current page. This is set by the user agent. Not all user agents will set this, and some provide the ability to modify HTTP_REFERER as a feature. In short, it cannot really be trusted.
'HTTP_USER_AGENT'
Contents of the User-Agent: header from the current request, if there is one. This is a string denoting the user agent being which is accessing the page. A typical example is: Mozilla/4.5 [en] (X11; U; Linux 2.2.9 i586). Among other things, you can use this value with get_browser() to tailor your page's output to the capabilities of the user agent.
'HTTPS'
Set to a non-empty value if the script was queried through the HTTPS protocol. Note that when using ISAPI with IIS, the value will be off if the request was not made through the HTTPS protocol.
'REMOTE_ADDR'
The IP address from which the user is viewing the current page.
'REMOTE_HOST'
The Host name from which the user is viewing the current page. The reverse dns lookup is based off the REMOTE_ADDR of the user.
Note: Your web server must be configured to create this variable. For example in Apache you'll need HostnameLookups On inside httpd.conf for it to exist. See also gethostbyaddr().
'REMOTE_PORT'
The port being used on the user's machine to communicate with the web server.
'SCRIPT_FILENAME'
The absolute pathname of the currently executing script.
Note: If a script is executed with the CLI, as a relative path, such as file.php or ../file.php, $_SERVER['SCRIPT_FILENAME'] will contain the relative path specified by the user.
'SERVER_ADMIN'
The value given to the SERVER_ADMIN (for Apache) directive in the web server configuration file. If the script is running on a virtual host, this will be the value defined for that virtual host.
'SERVER_PORT'
The port on the server machine being used by the web server for communication. For default setups, this will be '80'; using SSL, for instance, will change this to whatever your defined secure HTTP port is.
'SERVER_SIGNATURE'
String containing the server version and virtual host name which are added to server-generated pages, if enabled.
'PATH_TRANSLATED'
Filesystem- (not document root-) based path to the current script, after the server has done any virtual-to-real mapping.
Note: As of PHP 4.3.2, PATH_TRANSLATED is no longer set implicitly under the Apache 2 SAPI in contrast to the situation in Apache 1, where it's set to the same value as the SCRIPT_FILENAME server variable when it's not populated by Apache. This change was made to comply with the CGI specification that PATH_TRANSLATED should only exist if PATH_INFO is defined. Apache 2 users may use AcceptPathInfo = On inside httpd.conf to define PATH_INFO.
'SCRIPT_NAME'
Contains the current script's path. This is useful for pages which need to point to themselves. The __FILE__ constant contains the full path and filename of the current (i.e. included) file.
'REQUEST_URI'
The URI which was given in order to access this page; for instance, '/index.html'.
'PHP_AUTH_DIGEST'
When running under Apache as module doing Digest HTTP authentication this variable is set to the 'Authorization' header sent by the client (which you should then use to make the appropriate validation).
'PHP_AUTH_USER'
When running under Apache or IIS (ISAPI on PHP 5) as module doing HTTP authentication this variable is set to the username provided by the user.
'PHP_AUTH_PW'
When running under Apache or IIS (ISAPI on PHP 5) as module doing HTTP authentication this variable is set to the password provided by the user.
'AUTH_TYPE'
When running under Apache as module doing HTTP authenticated this variable is set to the authentication type.
$HTTP_SERVER_VARS contains the same initial information, but is not a superglobal. (Note that $HTTP_SERVER_VARS and $_SERVER are different variables and that PHP handles them as such)
You may or may not find any of the following elements in $_SERVER. Note that few, if any, of these will be available (or indeed have any meaning) if running PHP on the command line.
'PHP_SELF'
The filename of the currently executing script, relative to the document root. For instance, $_SERVER['PHP_SELF'] in a script at the address http://example.com/test.php/foo.bar would be /test.php/foo.bar. The __FILE__ constant contains the full path and filename of the current (i.e. included) file. If PHP is running as a command-line processor this variable contains the script name since PHP 4.3.0. Previously it was not available.
'argv'
Array of arguments passed to the script. When the script is run on the command line, this gives C-style access to the command line parameters. When called via the GET method, this will contain the query string.
'argc'
Contains the number of command line parameters passed to the script (if run on the command line).
'GATEWAY_INTERFACE'
What revision of the CGI specification the server is using; i.e. 'CGI/1.1'.
'SERVER_ADDR'
The IP address of the server under which the current script is executing.
'SERVER_NAME'
The name of the server host under which the current script is executing. If the script is running on a virtual host, this will be the value defined for that virtual host.
'SERVER_SOFTWARE'
Server identification string, given in the headers when responding to requests.
'SERVER_PROTOCOL'
Name and revision of the information protocol via which the page was requested; i.e. 'HTTP/1.0';
'REQUEST_METHOD'
Which request method was used to access the page; i.e. 'GET', 'HEAD', 'POST', 'PUT'.
Note: PHP script is terminated after sending headers (it means after producing any output without output buffering) if the request method was HEAD.
'REQUEST_TIME'
The timestamp of the start of the request. Available since PHP 5.1.0.
'QUERY_STRING'
The query string, if any, via which the page was accessed.
'DOCUMENT_ROOT'
The document root directory under which the current script is executing, as defined in the server's configuration file.
'HTTP_ACCEPT'
Contents of the Accept: header from the current request, if there is one.
'HTTP_ACCEPT_CHARSET'
Contents of the Accept-Charset: header from the current request, if there is one. Example: 'iso-8859-1,*,utf-8'.
'HTTP_ACCEPT_ENCODING'
Contents of the Accept-Encoding: header from the current request, if there is one. Example: 'gzip'.
'HTTP_ACCEPT_LANGUAGE'
Contents of the Accept-Language: header from the current request, if there is one. Example: 'en'.
'HTTP_CONNECTION'
Contents of the Connection: header from the current request, if there is one. Example: 'Keep-Alive'.
'HTTP_HOST'
Contents of the Host: header from the current request, if there is one.
'HTTP_REFERER'
The address of the page (if any) which referred the user agent to the current page. This is set by the user agent. Not all user agents will set this, and some provide the ability to modify HTTP_REFERER as a feature. In short, it cannot really be trusted.
'HTTP_USER_AGENT'
Contents of the User-Agent: header from the current request, if there is one. This is a string denoting the user agent being which is accessing the page. A typical example is: Mozilla/4.5 [en] (X11; U; Linux 2.2.9 i586). Among other things, you can use this value with get_browser() to tailor your page's output to the capabilities of the user agent.
'HTTPS'
Set to a non-empty value if the script was queried through the HTTPS protocol. Note that when using ISAPI with IIS, the value will be off if the request was not made through the HTTPS protocol.
'REMOTE_ADDR'
The IP address from which the user is viewing the current page.
'REMOTE_HOST'
The Host name from which the user is viewing the current page. The reverse dns lookup is based off the REMOTE_ADDR of the user.
Note: Your web server must be configured to create this variable. For example in Apache you'll need HostnameLookups On inside httpd.conf for it to exist. See also gethostbyaddr().
'REMOTE_PORT'
The port being used on the user's machine to communicate with the web server.
'SCRIPT_FILENAME'
The absolute pathname of the currently executing script.
Note: If a script is executed with the CLI, as a relative path, such as file.php or ../file.php, $_SERVER['SCRIPT_FILENAME'] will contain the relative path specified by the user.
'SERVER_ADMIN'
The value given to the SERVER_ADMIN (for Apache) directive in the web server configuration file. If the script is running on a virtual host, this will be the value defined for that virtual host.
'SERVER_PORT'
The port on the server machine being used by the web server for communication. For default setups, this will be '80'; using SSL, for instance, will change this to whatever your defined secure HTTP port is.
'SERVER_SIGNATURE'
String containing the server version and virtual host name which are added to server-generated pages, if enabled.
'PATH_TRANSLATED'
Filesystem- (not document root-) based path to the current script, after the server has done any virtual-to-real mapping.
Note: As of PHP 4.3.2, PATH_TRANSLATED is no longer set implicitly under the Apache 2 SAPI in contrast to the situation in Apache 1, where it's set to the same value as the SCRIPT_FILENAME server variable when it's not populated by Apache. This change was made to comply with the CGI specification that PATH_TRANSLATED should only exist if PATH_INFO is defined. Apache 2 users may use AcceptPathInfo = On inside httpd.conf to define PATH_INFO.
'SCRIPT_NAME'
Contains the current script's path. This is useful for pages which need to point to themselves. The __FILE__ constant contains the full path and filename of the current (i.e. included) file.
'REQUEST_URI'
The URI which was given in order to access this page; for instance, '/index.html'.
'PHP_AUTH_DIGEST'
When running under Apache as module doing Digest HTTP authentication this variable is set to the 'Authorization' header sent by the client (which you should then use to make the appropriate validation).
'PHP_AUTH_USER'
When running under Apache or IIS (ISAPI on PHP 5) as module doing HTTP authentication this variable is set to the username provided by the user.
'PHP_AUTH_PW'
When running under Apache or IIS (ISAPI on PHP 5) as module doing HTTP authentication this variable is set to the password provided by the user.
'AUTH_TYPE'
When running under Apache as module doing HTTP authenticated this variable is set to the authentication type.
Thursday, September 18, 2008
PHPCamp in Pune
Good opportunity for php developers
PHPCamp is a 'ad-hoc gathering' for PHP community. It similar to barcamp, but more focused towards PHP based web application development.
It is targeting all the PHP enthusiast and starters to join this technical extravaganza this means that anyone can come to PHPCamp and participate.
Event DetailsDate: 20th September 2008 (saturday) .
Time: 10:00am to 6:00pm (Whole day event) .
Site: http://phpcamp.org/
Sessions: http://phpcamp.org/index.php/Sessions.html
Venue:
Persistent Systems Pvt. Ltd.,
Plot No. 9A/12, CTS No. 12A/12,
Erandwana, Near Padale Palace (Opp Sharda Center),
Pune - 411 004
My Php Support
"This is where you can discuss all about PHP, ask questions and get help, code samples, examples, any events and that sort of things that are related to PHP!"
What is PHP?PHP is a widely-used general-purpose scripting language that is especially suited for Web development and can be embedded into HTML.
To help the developers who have any query about PHP. You can freely ask any question about PHP to us and we will try to help you to our best.
Ever wondered how popular PHP is? Check out the Netcraft Survey here. The number currently stands at 14 millions Domains as of now. That's how popular PHP is!
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