What is XML for, and what are the benefits to it?

I've heard a lot of hype about it, but never really checked it out… finally got interested in finding out what it's about!

We use XML to transfer data from PHP to Flash applications. Whenever Flash needs to pull data from a database, it connects to a PHP script. The PHP script in turn fetches the data from the database, formats it into XML and outputs the file. Flash application then parses this XML data.

I think what I described above is the most common usage for XML. That is, to share data between two separate systems.

XML is just an "Extensible Markup Language". Basically, it allows the creator to use their own markup tags. It is primarily used for exchanging data. For instance, if you had a client and a slave the slave may request a piece of data... say fetchusers. The server could respond in XML
<users><user><name>User1</name><e-mail>Email1</email></user></users>

Your slave then processes/consumes your xml document and has the data requested.

Just one example.

XML mean Extensible Markup Language, it allows one different programming languages to communicate.

Well that's kind of neat…

I don't really use Flash, or try to communicate any separate languages as a matter of fact, but it's still pretty neat!

Thanks for the valid info WHT :)!!!

Another common use for XML is making RSS feeds. If you have a "news & updates" section of the site for instance, it's nice to add a feed link. RSS is very simple to create, it follows a very basic format.

http://www.devshed.com/c/a/PHP/Rockin-RSS-with-PHP-on-your-HTML/

XML is meta data basically it mean it describe what data is for example:

<book>
<title>C# for dummies</title>
</book>

it's great if you going to send out data to the other end. you can use DTD for validation before sending it out. It can be use for many thing. I have seem it where you can use it like a light weight database, configuration file, webservice...etc.

XML, solution looking for a problem.

There is actually a new generation banking software "consultant" walking around town who really believes that it is faster to process large volume data interchange with XML than with say, a flat file. He *really* believes it. Mind you, he's never done something so menial as to actually write code.

There's one born every minute, and the birth rate is accelerating.

XML, solution looking for a problem.

Not exactly, XML does have practical uses. One of them being what I described in my previous post.

There is actually a new generation banking software "consultant" walking around town who really believes that it is faster to process large volume data interchange with XML than with say, a flat file.

XML does offer more flexibility than flat file. But I haven't used XML for large volume data so can't comment on that.

Two advantages of XML over plain file that come to my mind file are extensibility and data hierarchy. Look at this example:
<users>
<user>
<name>
<first>John</first>
<last>Doe</last>
</name>
<email>john@example.com</email>
</user>
<user>
<name>
<first>Jane</first>
</name>
<email>jane@example.com</email>
</user>
</users>

In the previous example it is easy to spot who owns the jane@example.com address because the data is hierarchly organized.
As for the extensibility, you can use the previous response from my server and if next month I add a new tag <web> to my response, your code will not break.

Although you can use XML for data storage, it is not made for that. It is made for data exchange, like a common language that two particular system both understand. Handling a large amount of data with XML is, generally speaking, not wise.

Personally, for web based applications I choose JSON over XML. I do not see why bother with XML at all.

I had to use XML on a project for a gaming site once. The WoW armory (http://www.wowarmory.com/character-sheet.xml?r=Firetree&n=Shampoop) and EvE API (http://myeve.eve-online.com/api/doc/) both use XML for video game character data that I had to parse and populate a database with. Show me a flat file that comprehensive.

Yay! I started a little hit and didn't even mean to, kudos to you guys!