I need someone to explain XML and RSS to me please

[tony_l]

1. I do not understand the hype surrounding XML. I can make an xml document. What I would do with it, I do not understand. Can anyone explain this to me?

2. RSS - is it extremely diificult to start your own rss feed? How does it work - starting your own feed?

3. RSS - I want to display an rss feed from another website, how do I do this?

-Sorry about the dumb questions, but this is something I feel I should know by now. I would go out and buy a few books, but my house can no longer support any more books - I have been told If I buy one more book I will be exiled to an island in the arctic. The articles I have read have not been entirely clear on the WHY behind xml or the HOW with RSS.

-Thanks in advance folks!

[Weedpacket]

As for why: http://xml.silmaril.ie/basics/whyxml/

As for the HOW - I don't know how many or which articles you've read or sites you visited or what they said or how much you've worked at and worked out on your own, so if I were to say anything it would all just be the same stuff all over again - and if it didn't help last time....

[tony_l]

Weedpacket wrote:

As for why: http://xml.silmaril.ie/basics/whyxml/

As for the HOW - I don't know how many or which articles you've read or sites you visited or what they said or how much you've worked at and worked out on your own, so if I were to say anything it would all just be the same stuff all over again - and if it didn't help last time....

Thanks for the link man, but it just re-hashed what the other articles have said - it provides a structured way to exchange data, it is free, blah blah blah.

Could you give me an example of what xml is used for? Let me give you an example - I read somewhere that xml is an excellent way to store data. How is that so? Why not put the information in a database and pull it out when you need it? I do not understand why you would create flat files to store data.

About RSS - The website http://www.rss-specifications.com/ is very informative, however they do not explain everything you need to know, such as:

1. How do I display news on my website. Foxnews has an RSS feeder that I would like to use, but it says you need a reader. Well all the readers I see go on your desktop - how do you put it on your website?

2. If I want to start my own RSS feed - how do I do that using just xml? Let's say I offer an rss feed - someone "subscribes" to it - how do they get constantly updated information from it?

You see - these are important questions that I think they would go into detail about, but they don't.

Anyone got more info?

[leatherback]

Hi Tony,

Instead of buying a book, have you considered Searchinf for a parser? Or for a feed producer.

These should get you started. As for what XML is used for: First of all.. The rss feeds. Also, all google-earth files are adaptations of XML, called KML (see http://database.hyperspectral.info/map/specmap.kml for a google-earth location xml output).

you can just have your database produce the feed, based on the title, description and a link of articles. The parser will retrieve this, and interpret it.

It is usefull, because, in the case of RSS, you do not have to worry about finding out all the details of the feeds when parsing them: The format is pre-defined. this is not an issue when dealing with one specific feed. But when you aggregate over many sites, format becomes an issue.

j.

[aksival]

I scripted my own RSS generator for my personal website. It's basically a blog that lists the 10 most recent entries in the feed. Every time an entry is added/updated it executes the script, which gathers the appropriate entries from the database and rewrites the XML file.

The specification, unlike some, is actually very easy to understand: http://blogs.law.harvard.edu/tech/rss

Some of the lines (site title, etc.) will be hard-coded. The rest will be dynamic. The trickiest part, for me, was the date/time being off by X hours, but it wasn't difficult to adjust once I figured it out.

That's the easy part. Parsing is a lot more complicated, but there is a promising effort at http://magpierss.sourceforge.net/

[bradgrafelman]

tony_l wrote:

Why not put the information in a database and pull it out when you need it?

Why not? Better yet, what if you have information that you update once an (hour/week/whenever) that you want any other site to have? Oh wait, they can't/shouldn't access your database.

This is where you could generate an XML file. Now, any other site can grab this XML file, parse it for the information they want, and do whatever is necessary with it.

[Weedpacket]

tony_l wrote:

Could you give me an example of what xml is used for?

I shouldn't have to; there are tons of examples already there to be seen: look at http://www.xml.org/ or http://xml.coverpages.org/xmlApplications; these sites should have been among the first you found when you were searching.

Look up the Docbook format, or XHTML, or SVG, or MathML, or [man]SOAP[/man], or OpenOffice. Have a look at how much Microsoft's Visual Studio and the .NET platform use it for storing pretty much every configurable parameter in the entire framework. (Just picking examples I use on a daily basis there).

That SGML that was mentioned wasn't just a passing fancy. There are terabytes of SGML documentation sitting around (sometimes in databases, funnily enough), these days slowly being converted to XML. You just don't see any of it because, like COBOL or Fortran, it's all in-house.

Not everything fits into a relational database. Trees, for example, need a lot of fiddling to work efficiently. XML is built for hierarchical data; relational databases are not.

but it says you need a reader.

Firefox has an RSS reader built into it. So does Thunderbird. So does IE7. You don't need an RSS reader unless you want to read RSS feeds, but that's not weird. It's same as if you don't need a web browser unless you want to browse the web.