Just a small correction. I could be wrong but I don't believe XML is a subset of SGML but created to be used instead of. It was created from the ground up to replace SGML(not the easiest language to work with).
On Monday 27 October 2003 23:21, Robert Cummings wrote: > On Mon, 2003-10-27 at 20:40, Simon Fredriksson wrote: > > I think I've missed something somewhere, but how do I use XML? > > Everywhere, there are big hypes about XML. I could proably google quite > > a bit on this, but could someone give me a hint on how to use it in, say > > datahandling? Or to parse a website (like the php docs). > > PHP docs are SGML as far as I can remember. I think XML is a subset of > SGML. I would agree that XML in many cases has been hyped, but from a > practical point of view it does also have a lot of merit. One of the > examples I have found for it to work extremely well is on my MUD project > (Multi User Dimension). For example let's say we have a player with the > following stats: > > strength > intelligence > wisdom > dexterity > constitution > > We could define an XML document which stores this data in clear, > concise, and human readable fashion such as the following: > > <player> > <strength> 15 </strength> > <intelligence> 19 </intelligence> > <wisdom> 18 </wisdom> > <dexterity> 14 </dexterity> > <constitution> 10 </constitution> > </player> > > This is a pretty simple format, the fields are self explanatory. Now one > of the great advantages of XML is its flexibility. Let's say I now want > to add support for a charisma field... well it's as simple as adding the > field to the data, and if it doesn't exist assuming a default: > > <player> > <strength> 15 </strength> > <intelligence> 19 </intelligence> > <wisdom> 18 </wisdom> > <dexterity> 14 </dexterity> > <charisma> 17 </charisma> > <constitution> 10 </constitution> > </player> > > In older data formats such as binary, to add such a field would > generally require that version information be stored at the beginning of > the document and then when the data is resaved it would be saved as the > newer version. This caused problems with multiple versions in existence, > whereas with XML since the fields don't necessarily need to have any > kind of order, we don't need to keep track of version, only whether or > not the field was included. The other alternative (if you had complete > control over the data) was to convert it all to the new format which was > generally a tedious job and required a fair amount of effort to ensure > the validity of the new format. This is quite a trivialization of XML, > but this is one of the main advantages I see for it. One could easily > define a multitude of other formats that are just as flexible, but > currently XML is well supported by the development community and so is > probably the better choice. As with all things, your mileage may vary. > > HTH, > Rob. -- Ryan Thompson [EMAIL PROTECTED] http://osgw.sourceforge.net ============================== "A computer scientist is someone who fixes things that aren't broken" --Unknown -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
