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What is XML?

34 replies on 3 pages. Most recent reply: Nov 22, 2005 5:37 PM by Chris Eidhof

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Chris Burnley

Posts: 1
Nickname: distiller
Registered: Sep, 2005

Re: What is XML? Posted: Oct 20, 2005 4:13 AM
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Some paragraphs would be nice, I started reading it and could be bothered finishing it.

Mark Thornton

Posts: 275
Nickname: mthornton
Registered: Oct, 2005

Re: What is XML? Posted: Oct 20, 2005 4:20 AM
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Property files are rather unpleasant if you have many characters outside of 8859-1. They are also not wonderful for structured values.

Danny Ayers

Posts: 4
Nickname: danja
Registered: Oct, 2005

Re: What is XML? Posted: Oct 20, 2005 6:27 AM
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I generally agree with the points you make here (and Tim Bray's responses). However I would argue that many of the limitations you describe have already been overcome using the Semantic Web languages. In fact I do argue that over at:

http://dannyayers.com/archives/2005/10/20/meaning-on-the-wire/

Patrick Ma

Posts: 3
Nickname: patrickma
Registered: Oct, 2005

Re: What is XML? Posted: Oct 20, 2005 9:41 AM
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I equate XML to a spoken language.
A spoken language facilities communication between parties.

Communication is much more efficient when parties speak the same language. Efficiency here is about parties' understanding of each other, parties' ability to articulate. It is not about how easy the language itself is. It could be any language as long as parties speak the same one.

Regions of people speak their own languages. It is efficient for them. However, to communicate efficiently outside of their regions, they would most likely have to learn another language. If there is a defacto language out there, it would eliminate the need to choose one. After all, you may choose one that is not understood by the majority.

So, when asked "What is XML?", we need a context. Personally, XML as it is is not good for self contained tools. For example, I can't think why property files need to be in XML. Who else is reading my programs property files?

In another context, chains of tools as in Jim's example. XML as is is not "efficient". Why force your tools to speak in a way that is not natural to them.

The only context I see XML is helping is data exchange between different independent systems. In this context, what we are looking for is a way that both sides understand. It could be anything as long as both sides understand it. It just happens there is XML.

I learned English and I am able to communicate with people knowing English. Among my Chinese friends and families, we speak Chinese. We communicate well and why would I force any of my Chinese friends and families to speaking English?

Regards,

Patrick

Carl Manaster

Posts: 24
Nickname: cmanaster
Registered: Jun, 2003

Re: What is XML? Posted: Oct 20, 2005 11:32 AM
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I'm in the midst of my first encounter with XML. I don't know if this is typical, but I think it's a problem. The legacy code I'm working with uses XML to talk between programs, but then the programs keep using the XML internally, passing the org.w3c.dom.Document around and never really resolving its members into classes, just pulling elements and attributes out willy-nilly as needed.

Which gives Java some of the characteristics of a language like Perl. It doesn't feel right to me. Not that untypedness is inherently evil or anything, just it's a bad fit for the language.

Is this a common experience? Suggestions for dealing with it? (including Get Used To It, if that's appropriate).

Thanks.

V.H.Indukumar

Posts: 28
Nickname: vhi
Registered: Apr, 2005

Re: What is XML? Posted: Oct 20, 2005 1:05 PM
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In simple terms, I think what XML has brought into the IT world, is a nomenclature for hierarchically structured data.
Don't say XML, say XML-InfoSet. That's what XML really is. We do not need the XML-Text format. We can use XML-Binary format for wire transfers. What we DO need is a common way to interpret the basic datastructure contained in the text/binary stream as 'Elements', 'Attributes' and their hierarchy. What many people forget is that XML is beyond the text-format. What XML-InfoSet brings to us is SAX, DOM, which uses a higher level of abstraction (Element, Attributes). It allows us to manipulate data uniformly. So, please realize that XML is not a serialization format. It is higher level abstraction for hierarchically structured data.

robert young

Posts: 361
Nickname: funbunny
Registered: Sep, 2003

Re: What is XML? Posted: Oct 20, 2005 7:53 PM
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> Don't say XML, say XML-InfoSet. That's what XML really is.

read Pascal on the silliness of Infoset.

> It is higher level abstraction for hierarchically
> structured data.

which is a lower quality of data than the RM. as one of my profs said: "there is more hierarchical data in programs than in the real world." Codd proved this. insistence is not equal to truth, justice, and the American Way.

Merriodoc Brandybuck

Posts: 225
Nickname: brandybuck
Registered: Mar, 2003

Re: What is XML? Posted: Oct 20, 2005 8:07 PM
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When I was taking my computer architecture class in college, RISC processors were all the rage. My professor had said that "RISC" was so over-used that it simply meant "good".

I think XML is at about the same point. XML means good. It no longer has any real technical meaning.

Ray Schweray

Posts: 2
Nickname: ngjans
Registered: Oct, 2005

Re: What is XML? Posted: Oct 20, 2005 11:32 PM
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This may be a naive observation. But it seems to me that XML has the nice property that it represents trees really well. Outside of parenthesized lists, which don’t represent attributes really well, I can not think of an ASCII structure that lets you know you really should be using a set of maps if everything has the same depth or something that requires a revolver if the content of the leaves reference other leaves. So if something does not have nice xml representation it probably is not hierarchal.

Todd Blanchard

Posts: 316
Nickname: tblanchard
Registered: May, 2003

Re: What is XML? Posted: Oct 22, 2005 1:19 AM
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> I can not think of an
> ASCII structure that lets you know you really should be
> using a set of maps if everything has the same depth or
> something that requires a revolver if the content of the
> leaves reference other leaves.

The nextstep classic property list (PList) format was much nicer than xml and works for arbitrary levels of nesting of Lists, Dictionaries, and Strings. You can write a recursive parser for one of these in about a page of code. The formats are:

dictionary: { key = value; key2 = value2; }
list: ( value1, value2, value3 )
strings are either bare tokens or quoted: "this is a string\n"

So you can do

{ artist = "Van Halen"; albums = ( { title=VH1; songs=(...)}, { title=VH2; songs=(...)),);}

I use these all over the place for persistent storage, config info, etc. I use xml only when forced by external requirements.

Tommy Carlier

Posts: 4
Nickname: tommyc
Registered: Oct, 2005

Re: What is XML? Posted: Oct 22, 2005 10:59 AM
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There are tons of alternatives for XML, most of which are probably more compact and/or more readable. Just check out http://www.pault.com/xmlalternatives.html

I actually created some different text-based, hierarchical formats, one of which you can find on my website. It's called SMEL (Some Modest Extensible Language), and it looks and feels a bit like some of the more popular programming languages: C#, Java, C++, ... It uses { } to contain child-elements. More info at http://users.telenet.be/tommycarlier/smel/

Krzysztof Sobolewski

Posts: 7
Nickname: jezuch
Registered: Dec, 2003

Re: What is XML? Posted: Oct 22, 2005 3:26 PM
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not that i carry bill's water, but winFS is a radical nose thumbing: relationalize (and embed in the OS, a la AS//400) everything. if it weren't a M$ initiative, i might want to see it succeed.

reiser4 has the potential to do that (someone only has to write a plugin). Let's support that, not winfs :)

Peter Hickman

Posts: 41
Nickname: peterhi
Registered: Mar, 2003

Re: What is XML? Posted: Oct 22, 2005 4:27 PM
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XML is a way for designers to cobble together archaic data formats that make no sense to anyone but themselves and pass it off as standards compliant in some way. "It has a 500 line DTD and seven name spaces what could possibly be wrong with it?"

It allows designers to create complexity where they are incapable of creating simplicity.

(No I am not having a bad day, why do you ask?)

robert young

Posts: 361
Nickname: funbunny
Registered: Sep, 2003

Re: What is XML? Posted: Oct 22, 2005 8:41 PM
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> XML is a way for designers to cobble together archaic data
> formats that make no sense to anyone but themselves and
> pass it off as standards compliant in some way. "It has a
> 500 line DTD and seven name spaces what could possibly be
> wrong with it?"
>
> It allows designers to create complexity where they are
> incapable of creating simplicity.
>
> (No I am not having a bad day, why do you ask?)

for those in the audience who thinks this is a joke/sarcasm, have a look at the ACORD schemas.

Mark Thornton

Posts: 275
Nickname: mthornton
Registered: Oct, 2005

Re: What is XML? Posted: Oct 23, 2005 4:31 AM
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> There are tons of alternatives for XML, most of which are
> probably more compact and/or more readable. Just check out
> http://www.pault.com/xmlalternatives.html

I looked in vain for character set declarations or an equivalent to character entities. Do many of these alternatives gain much of their simplicity by discarding or complicating international support?

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