Bin-Blog

PostgreSQL

2006-10-04T16:46:00.000+05:30

PostgreSQL is a RDBMS that many claim is better than MySQL. This is basically the only Open Source competion MySQL has. There are other Open RDBMS but they are not in the league of MySQL and PostgreSQL.

PostgreSQL is a open source object-relational database server(database management system). It supports many advanced features that are not in MySQL.

Features of PostgreSQL

Functions

This feature allow blocks of code to be executed by the server. Functions in PostgreSQL can be written many languages like PL/pgSQL, PL/Perl, plPHP, PL/Python, PL/Ruby, PL/Tcl and more.

Indexes

An index is storing some columns of a table separately to allows quick access to the table. This makes the index smaller than the original table (due to having fewer columns), and it is optimized for quick searching. Most RDBMS supports this.

Triggers

A database trigger is procedural code that is automatically executed in response to certain events on a particular table in a database. Triggers can restrict access to specific data, perform logging, or audit access to data. In addition to calling functions written in the native PL/PgSQL, triggers can also invoke functions written in other languages like PL/Perl.

MVCC

PostgreSQL uses Multi-Version Concurrency Control (MVCC), which gives an user a copy of the database, allowing changes to be made by one user without being visible to the other users until the change is committed. This also lets you 'roll back' to an older version of the database if necessary. This is similar to the Version control systems like CVS or Subversion.

Inheritance

This feature lets tables inherit the properties of a parent table. Data is shared between parent and child tables. For example, adding a column in the parent will cause that column to appear in the child table also.

Referential Integrity

PostgreSQL allows column constraints, foreign key constraints, and row checks.

Other features

And many more features like...

Views
Full, inner, left and right joins
Sub-selects
Encrypted connections via SSL
Point-in-time recovery

Another open source RDBMS is SQLite. This provides no serious competion for MySQL or PostgreSQL as it tends to a different need. It is a a small C library that implements a self-contained, embeddable, zero-configuration, single file SQL database engine. More about SQLite in the next post.

References

Comparisons

Blogger Changed the Feed URL for Blogger Beta Site...

2006-09-28T17:40:00.000+05:30

Blogger have changed the URL of the feeds of all the blogs that have upgraded to Blogger beta. In the previous version of blogger, the feeds were located in the location...

http://<blogger_id>.blogspot.com/atom.xml
(Eg. http://binnyva.blogspot.com/atom.xml )

Now it is in...

http://<blogger_id>.blogspot.com/feeds/posts/full
(Eg. http://binnyva.blogspot.com/feeds/posts/full )

This is a bad move by blogger. I just can't understand why they did it. They least they could do is redirect all traffic to the old location(http://binnyva.blogspot.com/atom.xml) to the new location(http://binnyva.blogspot.com/feeds/posts/full). By best bet is that they want to use REST architecture.

Another thing I don't understand is the result that is returned by the server when the feed URL is accessed. It returns the status 400 - Bad Request. Not 404(Page not found) but 400. I wish they would change this to 301(Moved Permanently) and redirect the user to the new feed location.

UPDATE : This problem is fixed now! Thanks Guys.

Syndication Errors

So why is this a bad thing? Why am I complaining when a page is moved. The answer is simple : Syndication. Many people who have subscribed to my feed using the old URL will not be able to access the feed. Many indexers like Technorati, Syndic8 etc. will not be able to access and index my blog. All because the URL for feed is changed.

Fortunately for me, I am using the Feedburner service. So I don't have a problem if the feed is moved. I just change the 'Original Feed' location in my feedburner account, and the the visitors will get the new data - without even noticing the change. If you are worried that Blogger will change the feed again, go register for this service(its free).

But I used the URL 'http://binnyva.blogspot.com/atom.xml' whenever I submitted my blog to an automatic indexer(Technorati,IceRocket,etc.). Now I will have to go around and update all those sites.

Bad move blogger. Hope you fix this issue soon.

New Features

That said, I have to admit the new feed system is cool. You can specify some quires and you will get a feed based on those quires.

For example, you can use the URL http://binnyva.blogspot.com/feeds/posts/full?max-results=5 and get the latest 5 posts instead of the default 25 new posts. Also there is a provision to get the feed for the comments of each post.(Eg. http://binnyva.blogspot.com/feeds/2591766938765279155/comments/full is the comments for the recent Fedora Core 5 - 64bit Vs 32bit post)

Some quires that work with the XML feed. There might be more, but these are the only ones I know. If you know any that are not included here, let me know and I will include them.

URL : http://binnyva.blogspot.com/feeds/posts/full

Parameters

max-results: The number of posts that should appear in the XML(Default : 25). Example : http://binnyva.blogspot.com/feeds/posts/full?max-results=5
start-index: The post from which the listing should be taken. 1 means latest, 2 means second latest and so on(Default : 1).

I think they are using an updated feed creator - the version given in the generator tag have changed. The new XML feed has Generator 'Blogger 7.00' while the older one has 'Blogger 6.72' as the generator.

RSS/Atom

Another thing I noticed was that the feed is available only in the atom format. In the previous version, they had both the Atom Format and the RSS format. Atom was available at http://binnyva.blogspot.com/atom.xml while RSS could be accessed at http://binnyva.blogspot.com/rss.xml . I can't find any way to get the RSS format in the new release(Blogger 7.0). Do any of you know where I can access the RSS format of the feed?

Top 5 Features Missing from Digg

2006-09-26T00:19:00.000+05:30

Digg is a great site - I use it daily to get myself up to date. Digg is one of the best news filtering service out there. A small definition of digg(for those who were living under a rock)...

Digg is a news website with an emphasis on technology and science articles. It combines social bookmarking, blogging, and syndication with a form of non-hierarchical, democratic editorial control. News stories and websites are submitted by users, and then promoted to the front page through a user-based ranking system.(From Wikipedia)

Like many other users of Digg, I too have a list of features I would like to see in Digg. These are the top 5(+1) features that are missing from digg.

Tagging

I just don't understand why this feature is not present in Digg. Digg is a poster boy for Web 2.0 and tagging is one of the core features of Web 2.0. Even Slashdot brought in tagging.

Bookmarking option - without digging

Many people digg an article because they want to mark it for reading latter - not because they read the article and liked it. I have done this many times. But if there is an option to 'bookmark' an article without digging it, the users will use that feature - giving more each digg more weight.

Link to original story in the feed

The Digg RSS feed is next to useless as it don't contain the link to the original story. The links is for the comment page for that story in Digg. I understand that diggs will lose some traffic if there is no need for the user to visit the front page, but is this a good long term strategy? Guys, you are a Web 2.0 site - you really have to provide a good feed. You if want, you can include the link to the comment page in the 'description' section, but please, include the link to the original articles.

New Stories

Despite what my friends think, I don't check Digg once every 10 seconds. The actual time is more like once every 10 hours or so. The problem is a lot of feeds get promoted to the frontpage in that time. So there is a good chance that I will miss out some of the digged articles. I would like a page that would show all the stories that have been promoted since the last time I visited that page.

For example, say I visited this non-existent page http://www.digg.com/new/ at 2006-09-23 10:00:00. The interface will be similar to that of the frontpage. I browse through the list of stories, merrily digging away. After my 'digging run' is over(say at 2006-09-23 10:30:00), I visit some other site, do some coding etc. till I feel the craving to check Digg again. So I visit the 'New' page again. Now only the diggs that has been promoted after 2006-09-23 10:30:00(time of the end of the last digg run) will be shown.

You would have to be logged in for this feature to work, which would be a good thing for Digg. If you don't want to log in, this can also be implemented using a cookie.

This feature is for the frontpage diggs - but can also be implemented for the 'Upcoming' Diggs too.

Link to external services

A link to external services like del.icio.us would be nice. Digg have provided a 'Blog This' options(which I have never yet used). But a much more helpful feature is a small link next to every post - "Bookmark this link in Del.icio.us". Or 'Seed this story in Newsvine'. Or whatever.

Bonus Feature : Pictures

Even though this feature is not essential, I thought it would be great if each story has an images associated with it to the right - like in del.icio.us or tech.memeorandum. Right now, images are only available for video links.

Your 'most wanted' feature for digg not here? If you have any feature that you would like to see in Digg, leave a comment.

Happy Digging.

Sementic Pullquotes

2006-09-22T23:37:00.000+05:30

"Pullquotes are basically some important text in the content that is repeated on a side with emphasis"

Roger Johansson of the 456 Berea st. recently wrote an article on how to make pullquotes using javascript. Pullquotes are basically some important text in the content that is repeated on a side with emphasis so that people will notice it sooner. This is often seen in magazines. Example to the right...

The method he used is to give the needed text a class, pull out the text using javascript and show it in the side. See original article for more details and code.

Advantages of this method

Avoids redundancy

This approach avoids having to enter the same content twice in the page. If you are using a pullquote, you will already have that text somewhere in the page.

A few problems with this approach

JavaScript is used for structure

JavaScript is used to create the pullquote - basically doing the job that rightfully belongs to (X)HTML. However, this don't really bother me - I am not that much of a purist. This feature also avoids redundancy of the text - which brings me to my next point.

Misses out on SEO advantage

The redundancy in the quote, propably containing some of our target keywords, is a good thing from an SEO point of view. Using this method will eliminate that advantage.

Not sementic

The 'span' tag is free of any sementic meaning - and frowned on in many purist circles. But, as I said earlier, it don't bother me much(I use spans liberally). But in this case, there is an opportunity do this right - using sementic markup is very easy...

<blockquote class="pullquote"><p> ... pullquote ... </p></blockquote>

...if you don't have issues about quoting yourself.

Text can't be changed

You will have to use the text exactly as it appears in the body - you will not be able to make any changes to it. Often you want to make cosmetic changes to the text before you make it a pullquote.

Don't need javascript

If someone who has a good browser(supports CSS) is surfing with Javascript turned off, he will not be able to see the effect.

Purely Sementic Method

A much simpler method of doing this is to just the proper markup to insert the quote and using CSS to position the text whereever you want. You don't really need JavaScript for doing this.

(X)HTML

<blockquote class="pullquote"><p> ... pull quote ... </p></blockquote>

CSS

This code is taken from the original article. Change it to fit your design.


.pullquote {
 float:right;
 width:10em;
 display:block;
 margin:0.25em 0.75em 0.25em 1em;
 padding:0.5em;
 border:3px double #ccc;
 border-width:3px 0;
 color:#333;
 background-color:#f0f0f0;
 font:italic 1.3em/1.3 Georgia;
}
.pullquote p {
 margin:0;
 text-align:center;
}

32bit Linux installed(Fedora Core 5)

2006-09-19T23:50:00.000+05:30

As said in the previous post, I have installed Fedora Core 5(32 bit) version on my system. A pity, I was starting to like the 64 bit version. The speed became bearable after you get used to it. Anyway I have just installed the 32 bit version - I have to configure it now. I will let you know what I think of the OS once the whole thing is set up.

I have stumbled upon a practical way to partition the HDD if you want to reinstall the OS every 6 months(the release cycle of many Linux Distros like Fedora Core and Ubuntu is 6 months). Of course, I will reinstalling you system every 6 months, but it is an option.

Windows Partitions(if any)
/boot - 200 MB for me
/ - The root partition
/home - Where all the user's information is kept
swap - The size of this drive must be twice RAM's size. If you have 1 GB RAM, you must have 2 GB Swap.

Make sure you have a separate /home partition - that way you can reinstall the OS without losing(or having to move) any of the files you are working on. Just make sure you choose 'Custom Partitioning' when installing the OS. Then format all the partition EXCEPT the /home partition.

Of course, if you choose to put your site in /var/www/htdocs(or some folder outside your home) you will have to backup those folders. Some folders that I have to backup outside home are...

/var/www/ - All my web development folder - htdocs, cgi-bin etc.
/var/lib/mysql/ - Database is stored here.
/etc/ - Configurations.
/var/cvs/ - CVS repository is in this folder.

Also if you are the root user, your files will be kept in /root - not in /home. So back those up too.

The rest of the files are in my home folder(/home/binnyva) - these files will stay intact as I did not format the /home partition.

A problem with this method is that creating the same user is a problem. For example, if I create a new user with the same username(binnyva), the new users files will overwrite the existing files. Also KDE does not play nice when I tried to use the old configurations - I can login - but KDE will not start up. I had to login as root and delete the '.kde' directory from my folder before I got it to work again. This is a huge problem - I spend days trying to configure the OS to my liking - now I have to do it again. I would appreciate it if there was some system to copy the system configuration when upgrading the system. This is especially improtant in the case of 6 month release cycles I spoke about earlier.

Fedora Core 5 - 64bit Vs 32bit

2006-09-15T00:01:00.000+05:30

I have just installed Fedora Core 5 64bit linux in my system. I like it, but there is some problems associated with its being 64 bit.

No Flash

Macromedia(now Adobe) have not released a Flash plugin for 64 bit Firefox. This is in most cases a good thing - as I won't have to watch annoying flash ads. But it is a problem when I am trying to view videos in YouTube or Google Video. Also, Google Analytics is impossible to use without Flash. There are some solutions like using a 32 bit firefox on a 64 bit linux - but I like it better if there is native support. For automated installation see Howto Install 32 bit Firefox with Flash w/sound and Java for AMD64.

Not much of an performance boost in Desktop systems

64-bit binaries are not twice as fast, either. You are unlikely to notice any discernible speed difference, particularly with desktop apps.

What you should (and shouldn't) expect from 64-bit Linux - A must read if you are torn between choosing a 64bit and 32bit OS for your system.

Can't get IE to work

As I have promised in the 'Installing Internet Explorer in Linux' post, I have installed IE using Wine in the system. I did this in a FC3 system(at work) and a FC5 system(at Home). IE works perfectly(or close enough) on the FC3 system - but fails miserably on the FC5 system. I think this is an issue with Wine. I had to hack it a bit to work with my 64 bit system.

Speed

Another problem I have noticed is that the system, on the whole, seems a bit slower than FC3. I have seen other complaints like this on the net - but very few valid solutions.

I am trying to speed thing up a bit by disabling unwanted services. But still I think that the FC3 was faster. I am going to upgrade my RAM to 1GB from the current 512 MB - maybe that will solve the problem.

If nothing works, I will install a 32 bit version of FC5. I will have to re-configure everything - but I need speed.

Object Oriented Programing(OOP) in JavaScript

2006-09-12T18:37:00.000+05:30

A quick link dump on JavaScript inheritance and other OOP techniques that are almost never used when coding in JavaScript.

Classical Inheritance in JavaScript: JavaScript is a class-free, object-oriented language, and as such, it uses prototypal inheritance instead of classical inheritance. This can be puzzling to programmers trained in conventional object-oriented languages like C++ and Java. JavaScript's prototypal inheritance has more expressive power than classical inheritance. By Douglas Crockford
Private Members in JavaScript: Some believe that javascript lacks the property of information hiding because objects cannot have private instance variables and methods. But this is a misunderstanding. JavaScript objects can have private members. Here's how. Again, by Douglas Crockford
How to achieve private, public, and privileged members in JavaScript: One core thing about JavaScript that tends to confuse people is how to get private, public, and privileged members. First off one might even question the fact of whether or not they’re useful or needed - and to one degree, they’re not. But like any OOP language that allows for declaration of private and public members, there’s not even a need for them there as well. By Dustin Diaz
Namespacing your JavaScript: Perhaps a very uncommon approach to developing web applications that require JavaScript (but should be more common) is namespacing your scripts. This can be done very simple-like in a manner that is painless and nice-looking. By Dustin Diaz
Private Static Members in Javascript: It was a widely held belief that javascript objects could not have private instance members, that all javascript object properties where public and could be accessed and changed with external code.
OOP in JS, Part 1 - Public/Private Variables and Methods: This page shows how to create private variables and methods in classes in Javascript through the rather simple example of a person.
OOP in JS, Part 2 : Inheritance: This section discusses inheritance in Javascript.
Object Hierarchy and Inheritance in JavaScript: JavaScript is an object-oriented language based on prototypes, rather than, as is common, being class-based. Because of this different basis, it can be less apparent how JavaScript allows you to create hierarchies of objects and to have inheritance of properties and their values. This paper attempts to clarify the situation.
Object-oriented JavaScript: JavaScript is not generally considered a robust programming language, especially when compared to languages such as Java or C#: it is interpreted, rather than compiled; it is dynamically, rather than statically, typed; and it is commonly considered a procedural, rather than an object-oriented, language.
JavaScript Object-Oriented Programming: It may be shocking news, but JavaScript is a very powerful object-based (or prototype-based, whatever you wish to call it) language. Yes, JavaScript is a powerful language, not just something that's handy for image rollovers and other corny, flashy effects. However, very few people who have used JavaScript realize its capabilities. If you're one of these people, this tutorial is aimed at you.
JavaScript and Object Oriented Programming (OOP): JavaScript is an excellent language to write object oriented web applications. It can support OOP because it supports inheritance through prototyping as well as properties and methods. Many developers cast off JS as a suitable OOP language because they are so used to the class style of C# and Java. Many people don't realize that JavaScript supports inheritance.
Introducing the best Javascript Inheritance Technique: Every programmer who's tried to apply classical Object Oriented techniques when developing with JavaScript, has at one time or another asked themselves the question: How do you call or invoke a super class method?

Blogger Beta

2006-09-06T10:04:00.000+05:30

I have upgraded to Blogger Beta - now I can access many more features - like labels, WYSIWYG template modification etc. Since I use a customized blog design, it has not been easy. In fact, it was quite hard. But was it worth it? I don't know yet.

New templating Language

The templating language has been changed entirely. Many new features have been added - and the complexity have gone up greatly. I understood the language - but I don't think anyone without a programming background would spend enough time to study it.

Loops

The <b:loop ... > tag lets you repeat a section of content multiple times with little or no changes. Example...

<b:loop var='post' values='data:posts'>
   <h2><data:post.title/></h2>
</b:loop>

Conditional Statement - If/Else

Shows the content only if the given statement is true(or false). Example...

<b:if cond='data:blog.url == data:blog.homepageUrl'>
 <data:title/>
<b:else/>
 <a expr:href='data:blog.homepageUrl'><data:title/></a>
</b:if>

Section - Widget - Include

The Section/Widget/Include system make the Drag and Drop template editing system possible. The section is a top level container which can contain multiple widgets. A widget can have many 'includable's. The includable with the id 'main' will be shown by default. You can display the other includable using the code '<b:include name='ID_OF_INCLUDABLE'/> Some sample code - this code shows the header of this blog...

<b:section class='header' id='header' maxwidgets='1' showaddelement='no'>
<b:widget id='Header1' locked='true' title='Bin-Blog (Header)' type='Header'>
<b:includable id='main'>
<h1 id="blog-title">
<b:if cond='data:blog.url == data:blog.homepageUrl'>
<data:title/>
<b:else/>
<a expr:href='data:blog.homepageUrl'><data:title/></a>
</b:if>
</h1>
<p id="description"><data:description/></p>
</b:includable>
</b:widget>
</b:section>

Very powerful - but complicated.

In Conclusion

I like the new templating system - it is complicated, but very powerful. If you are willing to spend the time to study it, you can make magic. Kudos to the Blogger team for bringing it out.

If you notice any problem this blog, let me know. I not have tested this in IE yet - I have linux remember?

Did you move your blog to blogger beta? Why not? If you did, how did it go? Leave some comments.

References

Deconstructing Blogger Beta - A comprehensive explanation of the blogger beta templating system.
New Features
Can I edit the HTML of my blog's layout?
Page Elements Tags for Layouts
Fonts and Colors Tags for Layouts
Widget Tags for Layouts
Layouts Data Tags

Fedora Core 5

2006-09-03T22:52:00.000+05:30

I have upgraded from Linux Fedora Core 3 to Fedora Core 5. I still have to not configured it fully, so a complete review will have to wait.

I had a few troubles getting Firefox to work as I need it - and I have great difficulty in believing that they did not include XMMS in the distro. Other than that, I am mostly satisfied with the OS.

More details and a decent review will be posted when I have finished configuring the system.

MySQL Storage Engines - MyISAM, InnoDB and others

2006-08-28T23:23:00.000+05:30

MySQL has a feature called Storage Engines - it supports multiple independent storage engines that can be used as handlers for different table types. Each table can be stored in a way that is most optimized for that particular table.

With this system, the developer can choose how a table must be stored - he can chose which storage engine is best for that particular situation. For example in a content management system, the table containing the contents will be read more often - so we will chose a storage engine better optimized for reading data(eg. MyISAM). But in the case of the table storing the logs, it must be written more often - so we chose a storage engine that is better at writing for that table. Having multiple storage engine makes sure that you can get the best optimization for any given situation.

There are many who believe this is a Bad Thing. In most other DBMS, the Administrator don't have to worry about such details - the DBMS will take care of this. I don't want to take sides in this debate - as for many people, this has become a religious issue. Anyway, as I am writing a series on MySQL, I cannot ignore this very important feature of MySQL.

I have only used two of MySQL many Storage Engines - MyISAM and InnoDB. The rest, I have not uses yet. Someday.

MyISAM

MyISAM is the default storage engine for MySQL. If you create a table in MySQL, without paying any attention to select a specific engine, then that table will be created in MyISAM(by default). This storage engine is the best for high-speed storage and retrieval. It also supports fulltext searching capabilities.

MyISAM is supported in all MySQL configurations. This engine is used for Data warehousing, read-only archives optimized for bulk operations, etc. as it is the best solution when you want flexible index formats, big scans and has a small disk footprint for data and index. This is not suitable for a typical OLTP application because of table-level locking, bad crash durability and lack of ACID compliance.

InnoDB

The InnoDB storage engine provide transaction-safe tables(BDB also does this). InnoDB is also included by default in all MySQL 5.0 binary distributions. This engine supports...

Row level locking
MVCC
Savepoints within transactions
More features for typical OLTP applications.

One of the main advantage of this engine is that you can rollback to a previous version of the database using its COMMIT/ROLLBACK support. InnoDB engine is more reliable than MyISAM.

Memory

The MEMORY storage engine provides in-memory tables. The MERGE storage engine will let you handle many identical MyISAM tables as a single table. Like MyISAM, the MEMORY and MERGE storage engines handle non-transactional tables, and both are also included in MySQL by default.

The main advantages of the MEMORY Storage engine are...

No disk footprint
Extremely fast

This is most useful for...

Summary tables
Simulations
Temporary operations(sessions etc)

CSV

The CSV storage engine stores data in text files using comma-separated values format. The main advantages of this approach are...

Very simple - data stored in plain text files
The database can be modified without the server
Export/Import couldn't be easier.

Other Storage Engines

There are many other storage engines supported by MySQL. Some of them are...

NDB Cluster
ARCHIVE
BLACKHOLE
FEDERATED
Falcon

If you are not satisfied with any of these engines, you can write your own engine.

Reference

MySQL Storage Engines - 8 part series on MySQL Storage Engines
Storage Engine (Table Types) - 15 part series
MySQL AB :: MySQL Storage Engine Architecture, Part 1: An Overview
Storage Engines and Table Types - MySQL Reference Manual

Live Validator - JavaScript Field Validation Scrip...

2006-08-24T23:17:00.000+05:30

Live Validator is a JavaScript program that will validate any form field as the user types the data using the regular expressions that you have specified.

Features

Key Validation: Valides the key as you type it. For example, if you just want numbers in a field, the user will not be allowed to enter alphabets.
Live Validation feedback: If the field validates, the color of the element will change
Attach a form to the validation.: This will show error when the form is submitted
Reasonable size: 4.2 KB uncompressed
Works in most major browsers.: At least the ones I tested in - Firefox 1.5/Linux, Firefox 1.5/Windows, IE 6, Opera 9/Linux, Opera/Windows
And more...: Many more features...

phpMyAdmin Tips and Tricks - Database Backup and R...

2006-08-20T23:25:00.000+05:30

phpMyAdmin is a big software - there are features that I have not used yet. But there are some features that are not very obvious - but could save you a lot of time.

Quick Table Browse

The normal way to seeing the contents of a table is to click on the table name in the left pane and then click on the 'Browse' tab in the top. But there is a one click way to do this - click on the small icon next to the table name in the left pane.

Default Table Selection

When you access phpMyAdmin, you get the main page - after that you have to chose from the drop down which database should be used. Wouldn't it be useful if the database you use most would be automatically selected on loading? You can do this by accessing phpMyAdmin using the following URL.

http://localhost/phpMyAdmin/?db=my_fav_db

You will have to change the database name and the location to the one in your system - but you got the idea right?

Database Backup

There are many ways to take a database backup using phpMyAdmin - but my favorite way is to take an SQL Dump.

Select the database you want to backup and click 'Export' tab in the main frame. Now select all the tables in the select box. You can select the format of the backup - like SQL, CSV, XML etc. We will select the SQL option. It is recommended that you check the 'Add DROP TABLE' and 'Add IF NOT EXISTS' checkboxs. This will make sure that the existing tables will be removed when restoring the backup. Now check the 'Save as file' checkbox. Then click the 'Go' button. Now you should see a download option for the database backup. You can save this file to you harddisk and run it later if you want to restore the backup. If you did not check the 'Save as file' option, the SQL dump will be shown in a textarea.

This can also be done using the 'mysqldump' command in linux using the following command.

mysqldump --add-drop-table --user=root DATABASE> backup_file.sql

Table Backup

If you just need the backup of a single table, select that table from the table list in the left pane and click the 'Export' tab. Now do the steps described in the database backup section. Here only the selected table will be backuped.

This can be done using the following command.

mysqldump --add-drop-table --user=root DATABASE TABLE> backup_file.sql

Restoring a backup

Click the 'SQL' icon() in the left pane - this will open a popup. Paste the SQL code you when you backuped the database in the textarea in this popup. Alternatively, you can chose the 'Import Files' tab in this popup and chose the location of the file you saved when backing up the data.

This is not a recommended method to restore large backup - if the backup file is more than 1 MB, don't try this. A better method is to upload the backup file to you host and restore the backup using the shell.

Installing and Configuring phpMyAdmin

2006-08-11T22:42:00.000+05:30

In the last post, I introduced phpMyAdmin. In this, we will deal with installation and configuration of phpMyAdmin.

UPDATE: This installation manual is for the older versions on phpMyAdmin. To see how to install the latest version, see the post Installing phpMyAdmin 2.8

My aim is to create a tool that could be used to administer your database in a development server. These directions are NOT for a production server. You will need much more security when installing phpMyAdmin on a production server. A good source for information on how to install phpMyAdmin securely is the series 'Doing more with phpMyAdmin'.

Installation phpMyAdmin

Get the latest version of phpMyAdmin from phpMyAdmin.net. The files will compressed - so you will have to extract it.

Create a folder called 'phpMyAdmin' in the document root of your server and extract the PHP scripts into it. That's it - the installing part is over.

Configuring phpMyAdmin

Necessary Information

Now we have to configure it - before starting this, make sure you have the following details...

Database Server address
Database Username
Database Password

For the sake of example I am going to assume that the following values...

Server : 'localhost'
Username : 'root'
Password : ''

Using the 'root' user with an empty password is one of the worst security blunders you can make - but what the hell, we are on a development server, right?

Editing 'config.inc.php'

Open up the file 'config.inc.php' in your favorite editor and edit the following values...

$cfg['PmaAbsoluteUri'] = 'http://localhost/phpMyAdmin/';

This is the absolute path for your phpMyAdmin directory. If you enter this location into a browser, phpMyAdmin should show up. I will not recommend that you use 'localhost' as the domain if you are on a network and expect others to connect to this phpMyAdmin setup. You should use 'http://<YOUR IP</phpMyAdmin/' in such a case. However if you are using phpMyAdmin for just your system, localhost will do fine.

$cfg['Servers'][$i]['host'] = 'localhost';

This is the database server address. If you look at the following lines in the file, you will notice that there is more than one instance of this line. This is for managing more that one database server using just one phpMyAdmin. Make sure that all the other hosts are set to empty - phpMyAdmin will ignore it if it is empty.

$cfg['Servers'][$i]['user'] = 'root';

The database user - in our case 'root'. Only the first instance of the line should be set - the other will be ignored if the 'host' option is not set.

$cfg['Servers'][$i]['password'] = '';

The password for the above given user - in this example we are using an empty password.

There are many other options - but you will not have to worry about them - they will do fine with their default values. However, if you are adventurous, feel free to experiment with the configuration options. The file well commented in detail - so you will have no trouble finding your way around - if you know a bit of PHP.

After all this is done, open up a browser and point it to http://localhost/phpMyAdmin/. If all went well, you will get the front page of phpMyAdmin.

References

phpMyAdmin
Installing phpMyAdmin - Official Documentation
Doing More With phpMyAdmin - A 7 part tutorial for configuring and using phpMyAdmin

Installing phpMyAdmin 2.8

2006-08-15T23:11:00.000+05:30

The install instructions I provided earlier will only work in the earlier versions of phpMyAdmin. The latest version(2.8.2.1 - as of Aug 15, 2006) has a much easier way of doing this.

Get the latest version of phpMyAdmin from phpMyAdmin.net. The files will compressed - so you will have to extract it. Create a folder called 'phpMyAdmin' in the document root of your server and extract the PHP scripts into it. That's it - the installing part is over. The latest version will automatically configure itself to run with these settings...

Database Host : localhost
Username : root
Password : (Empty)

For the example we provided the last time, this is all that is needed. But if you wish to configure your phpMyAdmin using more advanced options, open the folder you installed phpMyAdmin to(<Document Root/phpMyAdmin/>) and create a folder called 'config'. Make sure it has write permission. You can give it write permission with the following command(assuming that your are on a linux system)...

chmod 666 config

Now open the URL http://localhost/phpMyAdmin/scripts/setup.php. This will help you configure your phpMyAdmin.

The configuration is very straight forward - so I am not providing much details about it. If you have any doubt, reffer the documentation that comes with the installation.

After you have finished configuration, click on the 'Save' Button in the 'Configuration' section. This will create a 'config.inc.php' file inside the 'config' folder that we created earlier. You will have to manually copy this config file to you phpMyAdmin folder. After this is done, delete the config folder. You can do this with the command...

mv config/config.inc.php .
rmdir config

On a personal note, I still prefer the 2.6 Version of phpMyAdmin. Some pages in the latest version have a tendency to create horizontal scroll bars even on 1024x768 resolution.

Managing Databases with MySQL Clients - phpMyAdmin...

2006-08-07T23:01:00.000+05:30

There are many MySQL Clients(or database administration tools) out there - MySQL Front End, Tora, mysql etc. But in the web environment, one client rules - phpMyAdmin. phpMyAdmin is a PHP based(obviously) GUI administration tool for MySQL.

When I began programming in Linux, I could not use the DB Administration tool my co-workers were using. They were using MySQL Front End - and only the windows version was available for it. Since no one in my office used Linux, none knew another DBA for Linux. One suggested Tora, but I could not get it to run - some dependencies were missing. Anyway, I was forced to use mysql - yes, the command line client that came with MySQL Server. You can start it by bringing up a terminal and entering 'mysql' into it. Then you type every SQL command you want to execute into it. Trust me, it was not fun. The biggest problems was that I want to copy something and press 'Ctrl+C' - in the terminal 'Ctrl+C' is not Copy - its Close. So the client goes down. It was very irritating. Anyway I found phpMyAdmin before long and have been using it ever since(even after I got Tora running).

The biggest advantages of phpMyAdmin is that it is web based - it runs on any server capable of handling PHP. Because of this all the online Database Administration is done using phpMyAdmin. If you have a site of your own, and you have the control panel access to it, you will know what I mean. They database management part will be handled by phpMyAdmin. The phpMyAdmin site cites the following as the features of phpMyAdmin...

Browse, view and drop databases, tables, views, fields and indexes.
Create, copy, drop, rename and alter databases, tables, fields and indexes.
Maintenance server, databases and tables, with proposals on server configuration.
Execute, edit and bookmark any SQL-statement, even batch-queries.
Create and read dumps of tables - in various formats like CSV, SQL, etc.
Export data to various formats: CSV, SQL, XML, Excel and more.
Administer multiple servers.
Manage MySQL users and privileges.
Check referential integrity in MyISAM tables.
Using Query-by-example (QBE), create complex queries automatically connecting required tables.
Search globally in a database or a subset of it.
Support InnoDB tables and foreign keys.
Support mysqli, the improved MySQL extension.
And more...

phpMyAdmin is so commonly used that there is a book - Mastering phpMyAdmin for effective MySQL Management - that aims to teach it.

Reference

phpMyAdmin Project Documentation
Learning SQL Using phpMyAdmin
Doing More With phpMyAdmin - A 7 part tutorial for configuring and using phpMyAdmin.

MySQL - Database Management System

2006-08-03T04:19:00.000+05:30

In this LAMP series, we have looked at Linux and Apache - now we are going to have a look at MySQL.

MySQL is a multithreaded, multi-user, SQL based Database Management System(DBMS) under GPL license. It have become the most popular open source database because of its performance, reliability and ease of use. It is said to have more than 10 million installations.

The popularity of MySQL as a web application platform is closely tied to the popularity of PHP, which is often used with MySQL and nicknamed the Dynamic Duo.

MySQL have long been my favorite DBMS because its ease of use and great support in PHP. I have used MySQL in almost all the Web applications I have created over the years. This includes PHP as well as Perl apps. Ruby on Rails, the hottest framework right now, uses MySQL.

Features

Please note that some of the following features are only present MySQL 5.

Cross-platform support
Stored procedures
Triggers
Cursors
True VARCHAR support
INFORMATION_SCHEMA
Multiple independent storage engines(more about this later)
Transactions with the InnoDB, BDB and Cluster storage engines; savepoints with InnoDB
SSL support
Query caching
Sub-SELECTs (or nested SELECTs)
Full-text indexing and searching using MyISAM engine
Embedded database library
Full Unicode support
ACID compliance using the InnoDB, BDB and Cluster engines

Used In

Some of the most popular sites using MySQL are given below...

Multiple Versions of Apache on a Single System

2006-07-30T17:33:00.000+05:30

Some times it is necessary to have multiple versions on Apache in your system. The system I am currently working on has two versions of Apache - the first is Apache 1.3 with PHP 4 and MySQL 3. The second apache is Apache 2.0 with PHP 5 and MySQL 5. It is very easy to install multiple versions of Apache in your system - the only limitation is that you can't have all the versions run at once - only one instance of apache must be running at any one point.

I installed multiple versions of apache by using the 'prefix' keyword while compiling the software. To do this, you must have the source tarball of the apache program. Install it using the commands...

./configure --prefix=/usr/local/apache2
make && make install

The prefix keyword is the location where apache will be installed to. When create multiple installation of apache, keep changing this location - so that the previous installation will not be overwritten. You can start apache using the command...

/usr/local/apache2/bin/apachectl start

This command will start the apache server at /usr/local/apache2/ folder. The configuration files for this installation will be at /usr/local/apache2/conf/. Open the folder '/usr/local/apache2/' and you will see the other folders in this directory - like document root, logs etc. You can change the default locations of these folders using the httpd.conf file.

Apache can be stopped using any one of the following commands...

service httpd stop

/usr/local/apache2/bin/apachectl stop

Make sure that the running instance of Apache is stopped before starting a new instance - else a failure message will be shown. You can do this by using the command line...

$ service httpd stop
Stopping httpd:                        [  OK  ]
$ /usr/local/apache2/bin/apachectl start

Or you can use a neat script I created in Tcl/Tk. Save the following code into a file, say, 'ApacheRemote.tcl' and execute it using the command 'wish ApacheRemote.tcl'. NOTE: You must have Tcl/Tk on your system for this to work.


#!/usr/bin/wish
# ApacheRemote V 2.00.A
# http://www.bin-co.com/tcl/

proc showMsg { result } {
 .txt insert end "$result\n"
}

############################### GUI Code ####################################
label .lab_top -text "Apache Remote"
pack .lab_top

frame .frm_common
button .frm_common.but_stop -text "Stop Apache" -command {
 catch { exec "service" "httpd" "stop" } result
 showMsg $result
}
button .frm_common.but_status -text "Status" -command {
 catch { exec "service" "httpd" "status" } result
 showMsg $result
}
pack .frm_common.but_stop .frm_common.but_status -side left
pack .frm_common

frame .frm
button .frm.but_start -text "Start /usr/local" -command {
 catch { exec "/usr/local/apache/bin/apachectl" "start" } result
 showMsg $result
 #exit
}
button .frm.but_start_default -text "Start Default" -command {
 catch { exec "service" "httpd" "start" } result
 showMsg $result
 #exit
}

pack .frm.but_start .frm.but_start_default -side left
pack .frm

#Result Display Area
text .txt 
pack .txt -fill both -expand 1 -side top

bind . <Key-Escape> { exit }

Practical Uses for mod_rewrite

2006-07-26T22:47:00.000+05:30

I have explained how to use mod_rewrite to create structured URLs and about the most used mod_rewrite directives. Now to see some practical use of mod_rewrite in various situations.

URL Change

Good URLs don't change - but sometimes you have to do it. Move one file from its previous location to a new one. Even I have done it - I moved my site from http://www.geocities.com/binnyva/ to Bin-Co, OpenJS and BinnyVA. When you make such a move, you want to make sure that your visitors move with you. This can be done using mod_rewrite.

Lets say you are moving the a page from http://www.domain.com/oldfile.html to http://www.domain.com/stuff/newfile.html. Now when ever someone visits the oldfile.html file, they get a 404 error. You can use the following script to make sure that all visitors to the old page is redirected to the new one...


RewriteRule ^oldfile\.html$ http://www.domain.com/stuff/newfile.html [R]

Escape the Slashdot Effect

Slashdot Effect is a situation when a link to a smaller site appear in a heavy traffic site like Slashdot or Digg. Due to the huge traffic this brings, many site with low bandwidth will crumble. One method to prevent this is to deny access to all visitors who have come from the high traffic site(let us assume it is slashdot.org). There are other methods also(eg. mirroring). So you have two requirements...

Deny access to all from slashdot.org
Allow access to all others.


RewriteCond %{HTTP_REFERER} ^http://slashdot\.org [NC,OR]
RewriteCond %{HTTP_REFERER} ^http://www\.slashdot\.org [NC]
RewriteRule ^.*$ /denied.html [F]

The logic behind the above code goes somewhat like this...

RewriteCond %{HTTP_REFERER} ^http://slashdot\.org [NC,OR] - If the visitor have come from http://slashdot.org OR,
RewriteCond %{HTTP_REFERER} ^http://www\.slashdot\.org [NC] - if he have come from http://www.slashdot.org
RewriteRule ^.*$ /denied.html [F] - Show a 'Forbidden' message.

Prevent Image Hot Linking

Hot Linking is when someone links to a file from our server directly in a way that our bandwidth will be used when anyone visits the other person's site. For example, let say we have a cool picture called, say, 'cool_picture.jpg'. We have kept it in 'http://www.our-domain.com/pictures/cool_picture.jpg'. Now some guy from another site, likes this picture and decided to show the image in his site - so he uses the HTML code...

<img src="http://www.our-domain.com/pictures/cool_picture.jpg" />

So whenever someone visits this guys site, the image is fetched from our server - thus increasing our bandwidth costs. For this reason, this method is also known as bandwidth theft.

So how do we prevent it? The same method used in the last situations - look at the referrer, and if it is not ours, show a forbidden message.


RewriteCond %{HTTP_REFERER} !^$ [NC]
RewriteCond %{HTTP_REFERER} !^http://www\.our-domaincom/\.org [NC]
RewriteCond %{HTTP_REFERER} !^http://our-domain\.com/\.org [NC]
RewriteRule ^.*$ /denied.html [F]

Using Different Files for Different Browsers

As all good web designers know, different browsers have different ways of parsing the same CSS file. So your masterpiece in IE will look like something the cat brought in Firefox. One simple way of solving this problem is to use mod_rewrite and provide a different css file based on the visitor's browsers. Lets say we have a CSS file called 'style.css'. But for IE, we have created a special CSS file called 'style_ie.css'. For firefox, we have yet another CSS file called 'style_ff.css'. Our pages uses the HTML code...

<link href="style.css" type="text/css" rel="stylesheet" />

Now to provide different files based on the user agent of the visitor...


RewriteCond %{HTTP_USER_AGENT} ^Mozilla/(.*)MSIE
RewriteRule (.*)style.css$ $1style_ie.css [L]

RewriteCond %{HTTP_USER_AGENT} ^Mozilla/(.*)Firefox
RewriteRule (.*)style.css$ $1style_ff.css [L]

For more solutions to situations like this, see the URL Rewriting Guide from Apache Docs.

mod_rewrite module for Apache

2006-07-17T22:54:00.000+05:30

Along with the ability to password protect folders on the web server, another major use of the .htaccess file is the ability to 'rewrite' the URL. This will let you create more structured and easy to remember URLs. This module will redirect the user to one page while showing another URL in the address bar.

Application of `mod_rewrite`

Used in del.icio.us

This method is used to great effect in sites like Wikipedia and Del.icio.us. For example let us take a del.icio.us URL...

http://del.icio.us/binblog/javascript+ajax

This does not mean that there is a folder called binblog in the root of del.icio.us site. Nor does this mean that there is a file with the name 'javascript+ajax'. This trick is done using URL manipulation. In this example, the URL can be split into three parts....

http://del.icio.us/binblog/javascript+ajax
         ^^^         ^^^          ^^^           
      Site URL     User ID        Tags
    del.icio.us    binblog    javascript and ajax

The actual URL being called may be something like...

http://del.icio.us/show_bookmarks.php?format=html&user=binblog&tags=javascript+ajax

So how do the user see one URL and the server use another? That is the subtle art of URL manipulation. Before we see the details of this method, a small warning. You may not be able to get the concept at the first glance - it may be sometime before you understand mod_rewrite completely. So - don't give up, grasshopper. As one person puts it...

Despite the tons of examples and docs, mod_rewrite is voodoo. Damned cool voodoo, but still voodoo.
Brian Moore

Before going any further, let me also warn you that you must know regular expression to understand how this works. OK, now we can go further.

Using mod_rewrite

First we need a regular expression to extract the necessary elements from the URL. We will ignore the site URL(http://del.icio.us/) part. The URL is

http://del.icio.us/binblog/javascript+ajax

The Regualar Expression is...

^([^\/]+)\/([^\/]+)$

The extracted strings will be...

$1 = binblog (First Match)
$2 = javascript+ajax (Second Match)

To make this effect using the mod_rewrite module, open the .htaccess file your favorite editor and type in the following lines...

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteRule ^([^\/]+)\/([^\/]*)$ show_bookmarks.php?format=html&user=$1&tags=$2
</IfModule>

Now to test this, create a file called 'show_bookmarks.php' in the document root of your web server. I hope that I don't have to tell you that you need a LAMP setup to do this. You will need atleast Apache and PHP to do this.

After creating the 'show_bookmarks.php' file, enter the following code into it...

<pre><?php print_r($_GET); ?></pre>

Since this is just a test, I did not bother with all the HTML tags like <html>,<body> etc. But if you are a sticker for the rules, go ahead and make the full document.

Next, open this URL in the browser...

http://localhost/show_bookmarks.php?format=html&user=binblog&tags=javascript+ajax

You should get this result - the contests of the GET request...

Array
(
    [format] => html
    [user] => binblog
    [tags] => javascript ajax
)

Now try it with the URL...

http://localhost/binblog/javascript+ajax

If everything went well, this also should have the same output - that is...

Array
(
    [format] => html
    [user] => binblog
    [tags] => javascript ajax
)

Explanation

IfModule

<IfModule mod_rewrite.c>

This is an if condition - the code inside these tags will only be executed if the mod_rewrite module is loaded with apache.

RewriteEngine

RewriteEngine On

The 'RewriteEngine' directive enables or disables runtime rewriting engine. Here we are turning on the re-write Engine. Use the value 'off' if you want to turn of all rewriting.

RewriteRule

RewriteRule ^([^\/]+)\/([^\/]*)$ show_bookmarks.php?format=html&user=$1&tags=$2

This is the important statement. The proper syntax for RewriteRule directive is given below...

RewriteRule Pattern Substitution

The Pattern is a perl compactable regular expression.

Substitution part of the rewriting rule is the string which replaces the original URL for which Pattern has matched. You can use $n to insert regular expression captured strings - $1 is the first capture, $2 will be the second and so on.

One than one line of RewriteRule can be used. The order of useage is important as the second line will use the result of the first substitution as its input

</IfModule>

End of the if condition we started earlier.

Conditions

Some of you must have already seen a big problem in this approach. To see this problem, create a folder called, say, 'data' in your document root. Now create a file called 'something.txt' in this folder. Then try to access this folder from a browser using the URL.

http://localhost/data/

Now you see the problem, don't you? The above URL will result in the output...

Array
(
    [format] => html
    [user] => data
    [tags] => 
)

Our mod_rewrite rules have captured the URL of a valid file along with the other URLs. To solve this problem, we will use a feature of mod_rewrite called Conditions. Insert these lines in the .htaccess file.

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^([^\/]+)\/([^\/]*)$ show_bookmarks.php?format=html&user=$1&tags=$2
</IfModule>

See the line RewriteCond %{REQUEST_FILENAME} !-d? This will make sure that the requested file is not a directory. The line RewriteCond %{REQUEST_FILENAME} !-f will prevent files from being caught by the rewrite rule. The algorithm of these statements will look something like this...

if( 'Requested Filename' IS NOT Directory ) {
 if( 'Requested Filename' IS NOT File ) {
  Rewrite the URL.
 }
}

I hope you got the logic behind this - it took me a while to understand. Anyway, as I said earlier, don't be dissappointed if you don't get it at the first try - there is a lot of black magic involved.

Now try to access the file we created a little while back...

http://localhost/data/something.txt

You will see that it works perfectly(hopefully). Now try...

http://localhost/data/

Again the folder is being accessed. Now try a URL that must be re-written...

http://localhost/binblog/javascript+ajax

If all goes well, this URL will be caught by our system and will be redirected to the show_bookmarks.php file.

More about mod_rewrite in the next post(mod_rewrite Directives - RewriteCond and RewriteRule).

mod_rewrite Directives - RewriteCond and RewriteRu...

2006-07-22T23:01:00.000+05:30

In the last post on mod_rewrite, I used a basic example from http://del.icio.us to explain the working of the mod_rewrite module. Now I will try to explain the various options available in mod_rewrite.

RewriteEngine

This directive turns the rewrite engine on or off.
Syntax : RewriteEngine (on|off)
Example: RewriteEngine on

If you wish to disable rewriting, use RewriteEngine off instead of commenting out all the other lines. Since the rewrite engine is off by default, you have to turn it on every time you wish to use the mod_rewrite module. So the first line will be always...

RewriteEngine on

RewriteCond

The 'if' statement of mod_rewrite. The commands given below a RewriteCond line will be evaluated only if this returns a true value.
Syntax : RewriteCond TestString ConditionPattern [Flags]
Example: RewriteCond %{HTTP_REFERER} ^http://www.google.com [NC]

The RewriteCond has two arguments plus an optional third one.

TestString

There are three main types of strings that can be used in TestString part of the directive.

RewriteRule Regular Expression Captures - $N

Here N is a number between 0 and 9. If you use the string $1 in the TestString part of the RewriteCond directive, it will be replaced by the first capture from the regular expression for the corresponding RewriteRule - ie. the RewriteRule that will follow this condition.

RewriteCond Regular Expression Captures - %N

For this string, N is a number between 1 and 9. If you use the $1 in the TestString part of the RewriteCond directive, it will be replaced by the first capture from the regular expression for the corresponding RewriteCond - ie. the RewriteCond above this condition.

Server Variables

This are given in the format...

%{VARIABLE_NAME}

The most commonly used Server variables are given below. To see the full list of available server variables, see the apache manual page on mod_rewrite.

HTTP_USER_AGENT: A string containing the name of the browser the visitor is using. Eg 'Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8) Gecko/20051111 Firefox/1.5'
HTTP_REFERER: The URL of the page from where the current visitor came form.
REMOTE_ADDR: The IP of the visitor.
REMOTE_HOST: The visitor's host name.
SCRIPT_FILENAME: The filename of the page that was requested.
QUERY_STRING: The queries that was passed to the page.
REQUEST_URI: The called URI
REQUEST_FILENAME: The path of the file - ie. the URL of the page without the domain.

CondPattern

CondPattern is a regular expression - with some extra features...

!: You can prefix the '!' operator to any condition pattern to make RewriteCond return true if the pattern does NOT match.
<CondPattern: Compares the two string and return true if the TestString is lexically lower than the given pattern
>CondPattern: Return true if the TestString is lexically greater than the given pattern.
=CondPattern: Return true if the TestString and pattern are equal.
-d: Return true if TestString is a directory(folder)
-f: Return true if TestString is a file

Flags

Flags are given inside squire brackets([FLAGS]). Two flags are available for RewriteCond...

NC: No Case - the case is ignored in matching.
OR: Use this to combine two consecutive RewriteCond with a logical OR - if this is not given, an AND condition is implied

RewriteRule

Provides the rules for rewriting URLs.
Syntax : RewriteRule Pattern Substitution [Flags]
Example: RewriteRule ^/user/(.*) get_data.php?user=$1 [NC]

This is were the URL rewriting actually happens. This directive has two arguments plus an optional third one.

Pattern

The pattern is a perl compactable regular expression used to match the current URL. You can capture this by using the parenthesis ie. '(' and ')'. All text between these will be captured and could be used in the Substitution part of RewriteRule.

Substitution

The actual URL that is to be called is given here. This involves the path of the script and the parameters that should be given to it. This supports all the special features of TestString(like $N, %N and Server variables) besides plain text. It also supports the '!','<','>' and '=' prefix operators as we saw in the CondPattern.

Flags

Flats are the third argument to the RewriteRule directive. This should be given inside square brackets([FLAGS]). Flags is a comma-separated list of these flags...

R - Redirect: The URL in the address bar will change if this flag is used - as the server will use the HTTP response of 302 (MOVED TEMPORARILY) when redirecting the page.
F - Forbidden: Using this flag immediately sends a HTTP response of 403 (FORBIDDEN). Use this flag with appropriate RewriteConds to conditionally block some URLs - for example image hot linking from external sites.
G - Gone: Sends a HTTP response header of 410 (GONE). This flag is used to mark pages which no longer exist as gone.
L - Last: Stop the rewriting process in this rule and don't apply any more rules. Think Perl's last command or the break command of C.
NC - No Case: Makes the Pattern case-insensitive.
QSA - Query String Append: This flag will append the query string from the current URL to the substitution string.

Eg.

RewriteRule ^/user/(.*?)/ get_data.php?user=$1 [NC,QSA]

Please keep in mind that this is just the most commonly used Flags - for the full list, go to the apache manual page on mod_rewrite.

Happy rewriting...

New Blog - BinnyVA

2006-07-13T23:44:00.000+05:30

After much waiting I finally have a blog in WordPress. So currently I have two blogs - Bin-Blog and BinnyVA. I plan to use this blog(Blogger) as a professional blog and the other one(WordPress) as a more personal one. That blog will have a lower post frequency - around one per week. So from now on, all post that would have been tagged with 'Personal' will be kept in the opther blog - this blog will be used exclusively for professional content.

Another plus side of using that blog is that I can get an opertunity to sudy Wordpress - one of the most succesful PHP project of these times. Knowing what makes it tick will do me much good - I will be able to port my many programs as WordPress plugins. I actually plan to do this with Online Sudoku.

So this post will be the last post in this blog to be tagged with 'personal'. If you want more posts of that genre, go over to my new blog.

Football Vs JavaScript

2006-07-09T22:01:00.000+05:30

The Stars

Football

Zinedine Zidane
Ronaldo
Wayne Rooney
Christano Ronaldo
Thierry Henry
And more...

JavaScript

The Teams

Football

Real Madrid
Manchester United
...

JavaScript

Yahoo
Google
...

Why Football is better than JavaScript

Football has a fixed number of Referees and Lines men.
In JavaScript, we get a new referee every time a new browser is made and a new lines man every time a new version is released.

In football, if the referee calls a goal, it is a goal and if he calls it a foul it is a foul.
In JavaScript, one referee will call an event a goal while another will call the same event a foul.

In football, if you made a foul, the referee will send you out.
In JavaScript, if that was the case, document.write and eval would be a thing of the past.

In football, if some players are playing a standard game, no referee will go around trying to make their lives a living hell.
In JavaScript, IE.

Ronaldo makes more money and more fans than PPK can ever hope for.

Why JavaScript is better than Football

Anyone who knows JavaScript can compete in the World Wide Web cup.
Anyone who knows Football can dream of compeating in the World cup.

In football, the referees will only check how you play - they don't help you.
In JavaScript, Firefox with some extensions to help you to 'play' better.

Using libraries in JavaScript is like having Robotic legs in football. Using these you can run faster, shoot straighter and more accurately than you could hope for using your natural limbs. And most of the referee will stay happy as long as you use these robotic legs.

Salary

2005-04-09T02:48:00.000+05:30

I got my first pay-check. Well, not actually a check but a huge bundle of cash. Not much - but it will do. What I really like about my job is that I can study new things there - so far I learned PHP and advanced CSS design.

Anyway, now I am a paid employee. I am one more step closer to my dream of making money by the millions - like my father. My father never made money by the millions - but he dreamt of it.

Got Job

2005-02-21T03:53:00.000+05:30

I got my first offical Job - as a perl programmer at Reubro International. This may well be the busiest times of my life. Upto now, life was a easy affair. But now I have to juggle multiple things while trying to stay sane.

Job - programmer
MCP course at IndiaOptions.com
CCNA course at IndiaOptions.com
BCA course at IGNOU(Indira Ghandhi National Open University)

Just to complicate things a litte more, I have some optional/semi-optional stuff I have to do. These include...

Maintain my websites
Study other languages like Python, Ruby etc.
Finish the Perl/Tk tutorial "Create GUI using Perl/TK
Read more books - currently reading
- My Experiments with Truth by M K Ghandhi
- Concise guide to Today's Religions by Josh MacDowell
- Joshua and the Flow of Bibilical History by Francis Schaffer
- And more.

Ahh! So this is how life is on the fast line tastes like.

Amazon Associate

2005-04-14T02:50:00.000+05:30

Today I signed up as an Amazon Associate - now my website has ads from Google, Amazon and Geocities. Practically filled with ads, don't you think? Must remove some ads - so I want to sign up for my own webspace. It costs money - but you gotta spend money to make money as they say. So the second I get my first google paycheck, I am going to sign up for a new account with some web hosting service. Problem is that I need a Credit Card for that - and as of today, I don't have one. Getting one will not be much trouble - but it will lighten my pocket 400 Rs per year - that's about $10.

Have to decide on a web host now - know anything good?

Update : Decided on Dreamhost - My New Site - OpenJS.com.

Bin-Blog

PostgreSQL

Features of PostgreSQL

References

Comparisons

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Blogger Changed the Feed URL for Blogger Beta Site...

Syndication Errors

New Features

Parameters

RSS/Atom

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Top 5 Features Missing from Digg

Tagging

Bookmarking option - without digging

Link to original story in the feed

New Stories

Link to external services

Bonus Feature : Pictures

Related Links

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Sementic Pullquotes

Advantages of this method

Avoids redundancy

A few problems with this approach

JavaScript is used for structure

Misses out on SEO advantage

Not sementic

Text can't be changed

Don't need javascript

Purely Sementic Method

(X)HTML

CSS

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32bit Linux installed(Fedora Core 5)

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Fedora Core 5 - 64bit Vs 32bit

No Flash

Not much of an performance boost in Desktop systems

Can't get IE to work

Speed

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Object Oriented Programing(OOP) in JavaScript

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Blogger Beta

New templating Language

Loops

Conditional Statement - If/Else

Section - Widget - Include

In Conclusion

References

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Fedora Core 5

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MySQL Storage Engines - MyISAM, InnoDB and others

MyISAM

InnoDB

Memory

CSV

Other Storage Engines

Reference

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Live Validator - JavaScript Field Validation Scrip...

Features

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phpMyAdmin Tips and Tricks - Database Backup and R...

Quick Table Browse

Default Table Selection

Database Backup

Table Backup

Restoring a backup

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Installing and Configuring phpMyAdmin

Installation phpMyAdmin

Configuring phpMyAdmin

Necessary Information

Editing 'config.inc.php'

References

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Installing phpMyAdmin 2.8

Application of `mod_rewrite`