Steps to Improve Front End

1. With reference to my last post that Front End Performance are more important than Back End performance I have finally managed to find a nice descriptive article stating how to exactly achieve it.

The below are some of the common steps taken at Yahoo to improve performance of Yahoo Products.
All the points are covered in this link http://developer.yahoo.com/performance/rules.html

1. The Importance of Front-End Performance

1. Make Fewer HTTP Requests
2. Use a Content Delivery Network
3. Add an Expires Header
4. Gzip Components
5. Put Stylesheets at the Top
6. Put Scripts at the Bottom
7. Avoid CSS Expressions
8. Make JavaScript and CSS External
9. Reduce DNS Lookups
10. Minify JavaScript
11. Avoid Redirects
12. Remove Duplicate Scripts
13. Configure ETags
14. Make Ajax Cacheable

In addition to these Yahoo also provides developers with their custom FireFox extension which finds out what components of your page are slow and what can be done for improvement.
download Page :
http://developer.yahoo.com/yslow/
https://addons.mozilla.org/en-US/firefox/addon/5369

Reduce your page load time

Ever wondered why your page loads slowly even when your database queries execute at lightning speed.
Ever wondered why Super sites like Yahoo, AOL, etc load faster than your site.

If you are still wondering than this small article and the link mentioned at the bottom may help you reduce your page load time.

In any optimization effort it's critical to profile current performance to identify where the greatest improvement can be made. It's clear that the place to focus for fast web pages is the front end:

1. There is more potential for improvement by focusing on the front end. Making the back-end twice as fast reduces response times by 5-10%, whereas making the front end twice as fast saves 40-45%.
2. Front end improvements typically require less time and resources than back-end performance projects.
3. Focusing on front end improvements has proven to work. Over fifty teams at Yahoo! have reduced their end-user response times by following the best practices described here.

As web applications evolve to contain more functionality and content, these best practices are expected to have an even bigger impact.

Results Php Benchmark tests:
http://www.php.lt/benchmark/phpbench.php

The above link serves only the programming aspect of PHP.
There is still lot of improvement you can do in JavaScript and DOM.
So keep googling you might end up with what you exactly want.

Send Header without error

One of the common errors a web developer often gets is "Headers already sent" error.This happens when we render some text/characters /space in the browser and then try to redirect the page using header function of php.
For long I always thought that header function will only work when there is nothing rendered before the header call.
But recently I discovered(ofcorse with help of google) that we can render anything before the header call and still redirect the page.

Normal Usage with error is


echo "This will give error"
header("location:http://www.yahoo.com");


echo "This will NOT give error";
header("refresh:0; url:http://www.yahoo.com");


Here refresh:0 means the page will load after 0 seconds(which is instantly).
Basically this can be used when we want to have delay the page loading say we want to load yahoo after 2 seconds.
In this case the code will be


header("refresh:2; url:http://www.yahoo.com");



So start using this header call and redirect the page anytime during page execution.

Store procedure usage in PHP

Stored routines (procedures and functions) are supported in MySQL 5.1. A stored procedure is a set of SQL statements that can be stored in the server. Once this has been done, clients don't need to keep reissuing the individual statements but can refer to the stored procedure instead.

A stored routine is either a procedure . Stored routines are created with CREATE PROCEDURE statements. A procedure is invoked using a CALL statement, and can only pass back values using output variables. Stored routines may call other stored routines.
A stored procedure or function is associated with a particular database.

Procedures can be created using CREATE PROCEDURE command of mysql.
To know the exact syntax visit Online MySql documentation.

Once the procedure is created we have to use it in php code for this PHP's mysqli extension allows you to access the functionality provided by MySQL 4.1 and above

In order to have these functions available, you must compile PHP with support for the mysqli extension(MySQL Improved Extension).

To install the mysqli extension for PHP, use the --with-mysqli=mysql_config_path/mysql_config configuration option where mysql_config_path represents the location of the mysql_config program that comes with MySQL versions greater than 4.1.

mysqli functions are similar to mysql functions, there is substitute for each mysql functions in mysqli.
For e.g.

mysqli_query() has to be used instead of mysql_query()

using mysqli_query() the stored procedure query can be called and its result can be fetched.

Note: if you have to use any of mysqli functions then you will have to use mysqli functions throughout the current mysql connection
i.e. from mysqli_connect() to mysqli_close() all intermediate functions used must be of mysqli and not mysql.

references:

http://in.php.net/
http://dev.mysql.com/doc/refman/5.1/en/

Control Flow Functions of MySQL

While doing web programming many times you fetch data from database and depending on the value fetched, the user is shown something or other.
In case of optional fields in table it is quite likely that the value may be NULL or something default that you have set.
Take for example and option field called product awards which lists all awards bagged by that product.

When you write query
SELECT pro_id, pro_awards FROM products

This will give info regarding all the awards bagged by products.
However since pro_awards is optional many records will contain value NULL.

To tackle this NULL value you check in php whether the fetched value is NULL, if yes you display "No awards bagged by this product".

You can also do this checking at database level to reduce some load on webserver.
And as Databases are configured at their optimum level the processing time is much faster than your php / any script.

This can be done this way:
SELECT pro_id, IF(pro_awards IS NULL,'No awards bagged by this product', pro_awards) as pro_awards
FROM products
Above was use of if-else construct in MySQL

You can also make use of Switch-case construct effectively.
SELECT pro_id, CASE WHEN pro_awards IS NULL THEN No awards bagged by this product' ELSE pro_awards END FROM products

Above examples are very simple to understand, I am sure you can come out with difficult situations and use these Control flow functions of MySQL effectively to reduce script execution time.

references: http://dev.mysql.com/doc/refman/4.1/en/control-flow-functions.html

Backward Incompatible Changes

Although most existing PHP 4 code should work without changes in PHP5, you should pay attention to the following backward incompatible changes:

• There are some new reserved keywords.
• strrpos() and strripos() now use the entire string as a needle.
• Illegal use of string offsets causes E_ERROR instead of E_WARNING. An example illegal use is: $str = 'abc'; unset($str[0]);.
• array_merge() was changed to accept only arrays. If a non-array variable is passed, a E_WARNING will be thrown for every such parameter. Be careful because your code may start emitting E_WARNING out of the blue.
• PATH_TRANSLATED server variable is no longer set implicitly under Apache2 SAPI in contrast to the situation in PHP 4, where it is set to the same value as the SCRIPT_FILENAME server variable when it is not populated by Apache. This change was made to comply with the » CGI specification. Please refer to » bug #23610 for further information, and see also the $_SERVER['PATH_TRANSLATED'] description in the manual. This issue also affects PHP versions >= 4.3.2.
• The T_ML_COMMENT constant is no longer defined by the Tokenizer extension. If error_reporting is set to E_ALL, PHP will generate a notice. Although the T_ML_COMMENT was never used at all, it was defined in PHP 4. In both PHP 4 and PHP 5 // and /* */ are resolved as the T_COMMENT constant. However the PHPDoc style comments /** */, which starting PHP 5 are parsed by PHP, are recognized as T_DOC_COMMENT.
• $_SERVER should be populated with argc and argv if variables_order includes "S". If you have specifically configured your system to not create $_SERVER, then of course it shouldn't be there. The change was to always make argc and argv available in the CLI version regardless of the variables_order setting. As in, the CLI version will now always populate the global $argc and $argv variables.
• An object with no properties is no longer considered "empty".
• In some cases classes must be declared before use. It only happens if some of the new features of PHP 5 (such as interfaces) are used. Otherwise the behaviour is the old.

§ get_class(), get_parent_class() and get_class_methods() now return the name of the classes/methods as they were declared (case-sensitive) which may lead to problems in older scripts that rely on the previous behaviour (the class/method name was always returned lowercased). A possible solution is to search for those functions in all your scripts and use strtolower().

This case sensitivity change also applies to the magical predefined constants __CLASS__, __METHOD__, and __FUNCTION__. The values are returned exactly as they're declared (case-sensitive).

• ip2long() now returns FALSE when an invalid IP address is passed as argument to the function, and no longer -1.
• If there are functions defined in the included file, they can be used in the main file independent if they are before return() or after. If the file is included twice, PHP 5 issues fatal error because functions were already declared, while PHP 4 doesn't complain about it. It is recommended to use include_once() instead of checking if the file was already included and conditionally return inside the included file.
• include_once() and require_once() first normalize the path of included file on Windows so that including A.php and a.php include the file just once.

Reference: http://www.php.net/manual/en/migration5.incompatible.php

Boolean Full-Text Searches

Full-text searching is performed using MATCH() ... AGAINST syntax. MATCH() takes a comma-separated list that names the columns to be searched. AGAINST takes a string to search for, and an optional modifier that indicates what type of search to perform. The search string must be a literal string, not a variable or a column name.

Interesting Full Text searches for web developers can be Boolean Full-Text Searches

The following examples demonstrate some search strings that use boolean full-text operators:

'apple banana'
Find rows that contain at least one of the two words.

'+apple +juice'
Find rows that contain both words.

'+apple macintosh'
Find rows that contain the word “apple”, but rank rows higher if they also contain “macintosh”.

'+apple -macintosh'
Find rows that contain the word “apple” but not “macintosh”.

'+apple ~macintosh'
Find rows that contain the word “apple”, but if the row also contains the word “macintosh”, rate it lower than if row does not. This is “softer” than a search for '+apple -macintosh', for which the presence of “macintosh” causes the row not to be returned at all.

The + and - operators indicate that a word is required to be present or absent, respectively, for a match to occur. Thus, this query retrieves all the rows that contain the word “MySQL” but that do not contain the word “YourSQL”.

reference : http://dev.mysql.com/doc/refman/4.1/en/fulltext-boolean.html