by JOANNA GADEL

A fantastic pace has been noticed in the web sector. As a result, various definite standards and techniques are emerging. Every time there is an improvement, the web site design and applications grow complex, and there is a subsequent impact in the common web programming too. Several web programmers (Like: http://www.webprogrammers.com.au/) face this problem while making a website. Web programming requires expertise on many different levels. Skills in user interface design, human machine interaction, information design, scripting, code library development, database design and database queries are some of the important facets that are supposed to be had in a smart database programmer. In many or all of these levels a web programmer can face problems, and any web pattern needs to have explained the design considerations across any or all of these levels.

As such we need to be able to find a programmer who is aware of the problems area and can implement the required solutions. The programmer jobs include the solution of the problems originated in the day to day web programming. But first we must know the places where the problems usually occur.

The Problems Area

Form processing:

Form processing is the first step to record the problem of getting and verifying input from a user. It is the main part of all web applications, though there are many different approaches for solving this problem available to the web developer.

The basic method remains the same other than the actual content being entered. All forms should:

• Show an empty form to the user • Confirm the data entered to be valid and depict an error if it is incorrect • Perform the required action by the use of the data

Using either a single or multiple page design forms can be implemented. A self-referring script is needed for the single page technique, while the user can enter, confirm and submit the data through multi-page forms.

Navigational Structure:

A consistent look and feel is established by a clean, structured navigation and information design. Users can easily find their location in the sites through a proper navigation system.

There are at most three kinds of navigational structures:

• Single level navigation carries a list of top level areas. • The user can then drill down through the different hierarchical parts that the multi-level navigation has created, and they can find their desired content. Generally the hierarchy is two level deep to keep the display simple.

• Third navigational structure is the dynamic multi-level navigation that uses a hierarchy. Here the user after selecting the parent can be able to see the next level of navigation.

Database Operations

Accessing database is a fundamental problem for web developers. It is a common problem for the While entering the data into the database and editing entries through specific functions or an abstracted database wrapper, most of the times the data is found to be erroneous; this makes it a good candidate for pattern. Nearly all the programmers including php programmer (http://www.getaprogrammer.com.au/), java programmer, sql programmer and asp .net programmer make this phase as an essential part for a smooth running of any database design. They make a user interface design to clear the process.

At a higher-level many objects or items, the data used is captured by a row in the database. Here exists a common problem for the web programmers creating a set of useful functions and information based on these items.

Authentication Problems

The authentication phase needs to be revised properly with the different levels of a cheap programming. Several familiar mistakes have been there in these levels, and we are to solve them without any delay.

• The web programmers do nothing as to record or track any request to authentication in the None Level. • In the Session Level the web programmers used to track this anonymous person by the current visit only. • Another problem is there while tracking the anonymous person across numerous sessions in the web site in the Visitor Mode. • We must authenticate the person when we finally have the User with the relevant information.

These levels should be thoroughly checked up and similar other implementations should be necessitated if need be. The above levels should be considered together while in case of authentication.

Error Handling

It is a great challenge to build graceful degradation into a website. It is a vital job to hire programmers who can catch the errors before they confuse the users. By logging and notifying the errors a professional coder can prevent these errors to happen again.

Keeping the site alive even if components are off-line, the database programmers can handle any error problem by serving the database requests in the backed-up database that is read-only also.

E-commerce Problem

Using form and authentication any problem in the E-commerce can be easily solved if it is detected earlier. Only, a particular pattern independent on a particular implementation of forms or authentication is to be built. But first an interaction is to be done with the user and backend processing of the data.

by Encaps

How to implement CAPTCHA with PHP and GD

So, you have a public submission form on your website (contact page, forum submission,blogs comment form) and need to prevent spam by auto-submitters. Common way to do this is to implement CAPTCHA - an image with randomly generated string (quote from Wikipedia, free online enciclopedia: “A CAPTCHA is a type of challenge-response test used in computing to determine whether the user is human. “CAPTCHA” is an acronym for “Completely Automated Public Turing test to tell Computers and Humans Apart”, trademarked by Carnegie Mellon University.”)

Simple and quick PHP solution for implemet CAPTCHA:

1) Make a PHP script which will generate a CAPTCHA image:
[?php
session_start();
header(”Expires: Mon, 26 Jul 1997 05:00:00 GMT”);
header(”Last-Modified: ” . gmdate(”D, d M Y H:i:s”) . ” GMT”);
header(”Cache-Control: no-store, no-cache, must-revalidate”);
header(”Cache-Control: post-check=0, pre-check=0″, false);
header(”Pragma: no-cache”);
function _generateRandom($length=6){
$_rand_src = array(
array(48,57) //digits
, array(97,122) //lowercase chars
// , array(65,90) //uppercase chars
);
srand ((double) microtime() * 1000000);
$random_string = “”;
for($i=0;$i<$length;$i++){
$i1=rand(0,sizeof($_rand_src)-1);
$random_string .= chr(rand($_rand_src[$i1][0],$_rand_src[$i1][1]));
}
return $random_string;
}
$im = @imagecreatefromjpeg("captcha.jpg");
$rand = _generateRandom(3);
$_SESSION['captcha'] = $rand;
ImageString($im, 5, 2, 2, $rand[0]." ".$rand[1]." ".$rand[2]." ", ImageColorAllocate ($im, 0, 0, 0));
$rand = _generateRandom(3);
ImageString($im, 5, 2, 2, " ".$rand[0]." ".$rand[1]." ".$rand[2], ImageColorAllocate ($im, 255, 0, 0));
Header ('Content-type: image/jpeg');
imagejpeg($im,NULL,100);
ImageDestroy($im);
?]

2) Add the following line at the top of the page where you need to implement the CAPTCHA (there should not be any output before this line, except you use php functions ob_start() and ob_end_flush() to turn on output buffering):
3) Add the following line for check is CAPTCHA entered by visitor valid, before the line where you will proceed submitted message:
[?php if($_SESSION[”captcha”]==$_POST[”captcha”])
{
//CAPTHCA is valid; proceed the message: save to database, send by e-mail …
echo ‘CAPTHCA is valid; proceed the message’;
}
else
{
echo ‘CAPTHCA is not valid; ignore submission’;
}?]

4) Finaly add the CAPTCHA to the form:
[img xsrc=”captcha.php” mce_src=”captcha.php” alt=”captcha image”][input type=”text” name=”captcha” size=”3″ maxlength=”3″]

P.S.
notice:
- the tags “[?” and “?]” in code samples above should be replaced to the “”, you may download original article and code sample here: free download php captcha demo

- requirements: a webserver (windows or linux no matter) with PHP engine, with GD (graphic library) support, you may check your php settings with phpinfo() function

- you need some blank jpg image for use it as background for CAPTCHA string
About the Author 4-year PHP developer