Talk:XML/Archive 1

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[edit] Spring 2005 re-write

The whole article is not good enough; it is flabby, poorly organized, and in places misleading. Also some examples would be welcome. I plan to spend the next week or so rebuilding carefully, and will keep progress notes here. The first step is to go and work on Markup language to introduce the notions of presentational, procedural, and descriptive markup. Tim Bray 22:32, 16 Apr 2005 (UTC)

Good examples. For clarity about the root element in syntax overview, reference the recipe example.
Change "Every XML document must have exactly one top-level root element (alternatively called a document element), so the following would also be a malformed XML document:"
to "Every XML document must have exactly one top-level root element (alternatively called a document element). The element 'recipe' is the root element in the example above, and the following would be a malformed XML document:" Burnett.john 03:48, 28 April 2006 (UTC)

[edit] XML + CSS in IE and Mozilla

"This process is still not yet stable as of March 2004 in those browsers, in other browsers such as the Opera web browser this works very well."

Seems fine here with a superficial test. What doesn't work?

It would be helpful if the definition of XML did not contain one of the words in the abbreviation; i.e Markup is found in the definition twice. The equivalent is a definition of an Apple: an apple is an apple, which is a type of apple.

[edit] Is XSL only for making PDFs?

I am rather suspicious of the claim that "XSL itself is intended for creating PDF files", but I haven't changed it because I don't know much about either XSL or PDF (I came here looking for some information) ... Just wanted to draw this to the attention of someone who might know enough to make any necessary changes. If I'm wrong, sorry! Tremolo 01:17, 29 Jan 2004 (UTC)

It is wrong. It should say XSL can be used to genrate any type of file, e.g. PDF files. Mr. Jones 08:01, 22 Jun 2004 (UTC)

I think this is great stuff. Good job.

[edit] Poor terminology in the article

I am finding the use of terminology here a little confusing. You say that Doc Book is an XML language. I would say it is a particular DTD, and a DTD is a possible way of defining the elements of a particular XML language. Alternatively, an XML language can specify its element by a Schema, or simply define its elements within each document itself. Also, one of its main features is its flexibilty compared with HTML. Each user can, indeed, define their own mark-up language by defining each required and optional element for their language. Finally, the entire Doc Book DTD has been made available by O'Reilly online, and I suggest you provide a link to it. RoseParks

Yeah, DocBook probably isn't the best example, because it can be implemented in SGML as well. I'll reword to use something better. XML is not itself a markup language; specific applications of XML (defined by a DTD or schema) are. I'm not sure of a better way to word that.

[edit] What kind of language is XML?

It has occured to me that one way of thinking about XML is as a specification for the encoding of information. And, as is pointed out above, is not really a language in itself in the sense that it doesn't have its own vocabulary. The RDF (Resource Description Framework) states something to the effect of letting XML handle the issues with globalization (Unicode) and data formatting through the XML element/attribute/text value syntax and through other low-level transport considerations.

In most representations of multiple levels of XML applications that I see, it starts looking a lot like the OSI Model for networks. In the same way that applications run on top of TCP or UDP which run on top of IP (I think I got the order right), the DocBook "application" or RDF or any of the zoo of XML-based languages build on top of XML or could be done in SGML, or dozens other forms of data representation.

StWeasel

XML is really a language in itself, with its own vocabulary (made up out of < and > and other such characters and groups of characters), its own grammar, et cetera. But it is a language whose sole purpose is to describe another language, which seems to confuse people (just like with HTML); the metalanguage gets mistaken for the languages it describes.
What is stated above is that XML in itself is not a mark-up language, and that is true.--branko

While it might be arguable that it has a vocabulary, I can definitely agree on the characterization of XML as a metalanguage. It seems that the distinction I draw is that XML is essentially a mere specification of a syntax (how symbols can be put together to form the primitives of a language), but depends on other specifications as extensions (XHTML, MathML, RDF and the like) to provide a semantics (what can actually be expressed and how this expression is interpreted for meaning). It seems to me very much like saying that ASCII is a language, but from certain viewpoints I can see how this would be a valid statement. -- StWeasel

A question for the mathematicians out there: Is XML a formal language? (Or maybe a formal meta-language?)

When I'm reading the page, I don't see enough emphasis on XML's strictness. The words are there, certainly, but I'd like to—for example—to move the concepts of well-formed and valid up to be more prominent. But I'm wondering, can I call XML "formal"? And when the word "formal" appears in the introduction, should it be linked to formal grammar?

DanielVonEhren 16:13, 1 Feb 2005 (UTC)

[edit] Use of XML in Mac OS X

SHould we mention that Apple's OS X uses XML for most of its stored property settings (ie the equivalent of the weindows registry), the plist files? -- Tarquin 12:37 May 8, 2003 (UTC)


[edit] Removed text

Deleted following:

  • The document must identify itself as an XML document with a preliminary declaration to this effect. This declaration is known as a prolog. It will contain information about the XML version and possibly also information about encoding and whether the XML file is standalone or not.

Read the [spec http://w3.org/TR/XML], and see how above is false.

I removed this sentence from the article: Also, again unlike HTML, XML tags explain what the data means rather than how simply to display it. I don't see how something like this can be said about a purely syntactic specification, also eg. XHTML is a concrete example that this is misleading at best. Maybe something similar but NPOV could be put in as a statement about recommendations and best practices. -- Mp 09:31, 27 Aug 2003 (UTC)

[edit] Strengths and weaknesses re:n-tier systems and XML

I've just removed the following section from the weaknesses section (and rewrote it in part):

if one is coding an object-oriented system running on a relational database, then adding an XML front-end involves three different architectural metaphores. Mapping between these layers adds much complexity to design and development. Alternatively keeping information in XML works quite well for storage and messaging, but not for business logic. While XSLT exists as a transformation language it is declarative and not intuitive for procedural programmers. Also because XSLT programs are XML documents they are hard to read and thus to understand. This area of n-tier XML architecture is ripe for innovation.

I've tried to keep some of this statement, but this is overly long compared to the rest of the section. Part of this weakness is not really inherent to XML; if you're developing an OO system on a relational database it's not the fault of XML that adding XML support adds complexity.

That said, I think the article could use a lot more work, and one would be to extend the strength and weaknesses section significantly. The article was definitely POV-biased towards XML previously, and probably still is (and this is coming from someone who likes various XML technologies). There is a huge debate pro and contra XML (and its various technologies) that we could capture. Martijn faassen


[edit] Should the syntax be described in detail? Should it be complete?

The article shouldn't go into the details of the syntax of XML, especially when not all of it is covered. A definition of well-formedness is given that refers to elements, but "element" is never defined. I think a short example of an XML document is sufficient; anybody wanting more can read the spec. -- 64.81.99.73 20:20, 1 Sep 2003 (UTC)

[edit] What does "Compatibility with web and internet protocols" mean?

"Compatibility with web and internet protocols" - What does this mean, as an advantage? The internet protocols (HTTP, FTP, SMTP/MIME, etc...) appear 'compatible' with anything that's a sequence of bytes and has a MIME type. Is the author referring to the fact that XML looks like HTML? --Alaric 14:07, 26 Apr 2004 (UTC)


"Also, again unlike HTML, clever choice of XML element names allows the meaning of the data to be retained as part of the markup. This makes it more easily interpreted by software programs." - also strikes me as wrong; how does the choice of element names impact software programs? I can't think of many cases of software programs doing more with element names than passing them on to somewhere else, or identity-comparing them with hardcoded ones it has been told to expect. Did the author mean that good choices of element names makes the markup more easily interpreted by *humans*? --Alaric 14:07, 26 Apr 2004 (UTC)


Many of the examples of why XML is good, given here, are really applicable to any structured data format - particularly around the recipe example. Most of them look like the reasons why publishing documents as XML is better than publishing them as HTML, to me? --Alaric 14:07, 26 Apr 2004 (UTC)

1) The transport method _interent protocols_ receive/present no advantages because XML is used. Actually if XML is used, usually bandwidth is increased.

2) How compatible XML is with the web or whatever porduct out there that accepts XML has to more with the parsing engine and funcitonalty it presents than with the run-of-the-mill web services, read; web browsing.


The claim is unfounded (and does not in fact appear anywhere in the article) but was probably somewhat confusedly based in the fact that XML was designed with the Web in mind. Doc. type declarations must use a URL reference for the DTD, for instance. Other than that, the criticism is of course valid, its main advantage is that the syntax it is rigidly defined and therefore tools can automatically validate etc, plus that if everyone uses it, a lot of "synergy effects" should be achievable. -- Schnolle 19:59, 2004 Oct 22 (UTC)

[edit] Was XML intended as a successor to HTML?

I have a theory that XML was originally designed within the W3C as a replacement to HTML - the logic next step from a CSS-based world, changing <div class="foo"> to just <foo>, and a more powerful CSS - and that the conversion from this to 'data interchange' has caused some confusion.

--Alaric 14:07, 26 Apr 2004 (UTC)

It certainly was intended to be used this way, but this kind of support has not been implemented in IE very well (and development of IE seems to have stopped in 2001). Also the specifications in this direction have not been developed very far. Mr. Jones 08:38, 22 Jun 2004 (UTC)

Nope, XML was never intended as a asuccessor to HTML. I was there and I know. Tim Bray 07:24, 11 Dec 2004 (UTC)

It might be more accurate to say that the press picked up on the idea that XML was a successor to HTML. It would be interesting to trace where that idea came from: obviously, "the next HTML" made better press than "SGML on the Web" (SGM-what???), so the idea spread fast in XML's first year or two. Whatever W3C working group members and staffers did or did not actually say, much of the early W3C XML specification work was related to generic (i.e. non-XHTML) XML in the browser -- think of XLink, XSL(T/-FO), XPointer, XML Stylesheet linking, and even DOM. Data-oriented XML specifications, like SOAP or XQuery, mostly came later. David Megginson 00:03, 7 Apr 2005 (UTC)

[edit] history

why is there no history of how XML came into being on this page?

because you haven't written one.
so somebody did. It was horribly wrong, so I re-wrote it.

[edit] Document model versus schema

I can see that document model might be confusing with document object model (although it's harder to see how it could be confused with DOM).

On the other hand, I found it very confusing to see schema used to describe the thing-that-you-validate-against and also to describe one particular validation technology. The capital letter is very subtle. I got the phrase document model out of the O'Reilly book (Ray, Eric T. (2003). Learning XML, 2nd Edition. O-Reilly. ISBN 0-596-00420-6. ). The term is used a few times, first in Section 1.1.2.2 Validity. It's also used (more ambiguously) in XML In A Nutshell.

Maybe there is some other phrase we could come up with? I would think that when writing for an encyclopedia, we would prefer clarity for non-specialist.

DanielVonEhren 02:31, 5 Feb 2005 (UTC)

"Document model" is way too ambiguous IMO; I'm doubtful that you could find consensus on that choice of terminology if you're really referring to what is known in XML circles as a schema. To clarify my point on this, XML itself is a way of modeling a document, and the XML spec in fact describes two document models: the "physical" one, in which the document is comprised of a collection of entities consisting of encoded Unicode characters in certain allowable sequences; and the "logical" one, in which the document is comprised of elements, attributes, etc. …DOM, XPath, and the XML Information Set provide various alternative document models, at roughly the same level of abstraction. I would say that a schema is, at best, a specialization or superset of these models. I guess what I take issue with is the statement that a document is valid if it complies with a document model. Given the broad definition above, any well-formed document complies with various document models.
So, if we accept that "document model" is too broad, and "schema" is too arcane, what are we to do? I think that perhaps something dealing with "rules" might be best. Maybe "content rules"? "user-defined content rules?" I'm afraid that's too narrow, but it might make the most sense to a newbie. On the other hand, I think the way it is now is fine. It introduces the term schema, provides a brief explanation of what a schema is, in this context, and links to a schema article where the reader can flesh out their knowledge.
As for a better way to differentiate between "W3C XML Schema" vs (any) "XML schema", I'm open to suggestions. Not too long ago, the only mention of schemas in the XML-related articles were DTDs and (W3C) XML Schema (not consistently capitalized). I split the XML schema article in two in order to give an article on RELAX NG equal footing, and to disambiguate the idea of a schema in general, an XML-specific schema language, examples of specific languages, and schema instances. I'm sure it could still use some work; I was just happy to be able to get the RELAX NG reference in there. - mjb 07:49, 5 Feb 2005 (UTC)

Outside of a couple of nits, it looks like you and I are in broad agreement about the confusions and mis-directions. I'm not wedded to anything; I kind of liked your "content rules" idea.

As you've probably noticed, I've been doing various copyedits the last few days. IMO, there's lots of other basic improvements needed for this article, so I'm stickin' with the wording as it for now. Maybe if it marinates a bit, a better alternative will emerge (or maybe not).

One question though. I want to make sure I understand what you mean by:

I guess what I take issue with is the statement that a document is valid if it complies with a document model.

You're saying that there are many models (encoding, syntax, content), and a document has to comply with them all to be valid? The 1.1 Spec[1] says only

Definition: An XML document is valid if it has an associated document type declaration and if the document complies with the constraints expressed in it.

That definition might be too restrictive in our current context—talking about more than just DTDs)—but it points directly and only to the <mumble> (schema, document model, content rules, whatever).

DanielVonEhren 18:58, 5 Feb 2005 (UTC)

No, that's not what I was saying. Giving too broad of criteria for validity is what you appeared to be doing in the article, when you wrote "A valid document has data that conforms to its document model" and "An XML document that complies with its document model in addition to being well-formed is said to be valid."
As I mentioned above, all well-formed XML documents "comply with" many models: XML's physical and logical models, as well as those of the XML Information Set, DOM, and XPath. In other words, you said "its document model" as if there were only one model that could apply to an XML document, whereas there are actually many. Documents can comply with these models yet do not meet the real criteria for being valid.
Also, more than one schema (the kind of model you intended to talk about) can apply to a single document. So it would still be wrong to refer to "its" schema; you have to say something like "a given schema" or "a particular schema." - mjb 21:11, 5 Feb 2005 (UTC)

[edit] Capitalization

The XML Recommendation uses the capitalization Extensible Markup Language, not eXtensible Markup Language, despite the "XML" abbreviation. Think of "X" as standing for "Ex". Dpm64 02:45, 7 Apr 2005 (UTC)

[edit] 'obscure features'

"The syntax contains a number of obscure, unnecessary features borne of its legacy of SGML compatibility." Could someone elaborate upon what these obscure features actually are? porges 00:38, Apr 12, 2005 (UTC)

Tags. :) Actually, this info is in the spec. Look for the phrases "for compatibility" and "for interoperability". Examples include "--" being disallowed in comments, and the requirement that element content models be deterministic (see appendix E). I would guess that some would also consider notations, unparsed entities, and public identifiers to be legacy cruft as well. - mjb 01:14, 12 Apr 2005 (UTC)
I was hoping to be able to add a short list into the article, but they really are obscure, and the list wouldn't do anything more than confuse :P About the only thing that people are likely to come across in "normal" usage of XML is the "--" not being allowed in comments. porges 05:20, Apr 12, 2005 (UTC)

[edit] "No facilities exist for randomly accessing or updating only portions of a document."

Does not DOM allow random-access? I'm not sure about others (XQuery, XPath, XUpdate), but some of them may provide either the former or latter parts of the statement as well. porges 02:07, Apr 13, 2005 (UTC)

Yes, but not on disk. If you're using DOM, you cannot update a document unless you load it into memory, modify it, and write it out again. All of it, that is. There is no way to add or remote stuff in XML documents on disk (at least not that works for arbitrary XML files). Anon 15:50, 22 Jun 2005 (UTC)
Hmm, then I think the statement should be qualified to refer to a serialized document. — mjb 17:48, 22 Jun 2005 (UTC)
I second mjb; there should be more talk of serialization and deserialization.--Randomtask 15:08, 23 November 2005 (UTC)

[edit] Remove software links?

  • I suggest that we eliminate all software links (open or closed source). XML is so widely implemented that it does not make sense to single out individual software packages here, and linking to software is an obvious opportunity for contributors to abuse the article for personal gain. David 00:00, 2005 May 29 (UTC)
    • Given the lack of objections, I've gone ahead and drastically simplified the External Links section. There are, literally, thousands of specifications, tutorials, and software packages related to XML, so any list is arbitrary (should the ASCII list include every programming language and OS that supports ASCII?). Simplifying the list also diminishes the temptation to abuse this page for self-promotion of products, projects, specs, etc. David 21:10, 2005 Jun 17 (UTC)

Now that there is an XML editor article, we could merge the XML editor links into that article. That would just leave the parser links here. Anyone (aside from the companies at the other end of those links) opposed? — mjb 08:47, 31 January 2006 (UTC)

I support both mjb's proposal and a culling of the links at XML editor as in both articles it looks as if we are endorsing particular clients. I am a user and not a producer of XML editors, SqueakBox 13:41, 31 January 2006 (UTC)

[edit] Don't remove open source: they have valuable content

I agree partially: lot of commercial products are polluting this website.

Not totally: open source software are relevant, they havee content (the source code) we can read (programmers only, of course) and we can get information from that.

I propose that instead: remove commercial and shareware products. Open source must remain here.

Boole

[edit] Don't think this is a correct statement

The basic parsing requirements do not support a very wide array of data types, so parsing sometimes involves additional work in order to extract the desired data from a document. For example, there is no provision in XML for mandating that "3.14159" is a floating-point number rather than a seven-character string.

XML schema (and the set of basic types that are supplied) support floating point numbers, in addition to decimals (BCD) and double-precision floating point. Type checking is achieved via validation against the schema upon which the document is based. Keith Jun 10 2005.

XML Schema support and PSVI modeling are most certainly NOT part of the basic parsing requirements of XML. (Also, sign your name with three or four tildes, like this: ~~~~. They will be converted to your Wikipedia username and a datestamp automatically.) — mjb 21:08, 10 Jun 2005 (UTC)

[edit] Rearrangement

I moved History to the beginning, and put Strengths and Weaknesses after that. I think it flows better, from (1) describing what XML is (and where it came from) to (2) what it does to (3) how to use it (putting the Syntax and Validation sections together, etc.). I have no problem being overridden, of course. :P —tilde 02:07, August 2, 2005 (UTC)

[edit] XML Definition

It would be helpful if the definition of XML did not contain the words in the abbreviation; i.e the term 'markup language' is found as the definition of markup language twice. The equivalent is this definition of an Apple: An apple is an apple, which is a type of apple. Dec 9, 2005 crm —The preceding unsigned comment was added by 152.16.253.163 (talk • contribs) .

This article defines XML as a markup language, which is conveniently linked such that you can read what a markup language is, if you don't already know. └ UkPaolo/talk┐ 16:45, 27 January 2006 (UTC)

[edit] Dec/hex numerical character references

Numeric character references look like entities, but instead of a name, they contain the "#" character followed by a number between the ampersand and the semicolon. The number (in decimal or hexadecimal) represents a Unicode code point [...] But how does it distinguish between dec and hex numbers? In the example, &#038; has a decimal number (as one can find out by looking at an ASCII chart), but what would a hexadecimal number look like? - wr 12-dec-2005

Add an x prefix to show a number is hex: &#38; (decimal for &) is the same as &#x26; (hex for &). Should this be explained somewhere in the article? --Nigelj 19:13, 27 January 2006 (UTC)

[edit] XML on the web.... wow! POV... what about all the programs out there?

I'm new to this. I want a make an XML list for my small business so I can easilly sort a document to display one format and then a different format. I know that microsoft has XML for excel and for word. But what is all this stuff about the internet? This article appears to have a strong POV toward internet XML and doesn't talk very much about program XML. Maybe also we could have some links to important place that will help someone learn how to work with XML? --CyclePat 02:31, 28 January 2006 (UTC)

Usability on the Internet was a goal of the group that created XML, as mentioned in the article. I wouldn't call it POV to make mention of that fact. The Features of XML section of the article talks pretty much exclusively about how XML represents information, and shows no bias toward any particular application of XML. Perhaps the article could use some examples of how XML is used in applications, sure, but at the moment it's not really providing any examples at all, so I don't think it's particularly biased one way or the other.
Links to technical tutorials tend to get into linkfarm and spam territory (redundant, ad-supported sites exploiting Wikipedia articles). There are some tutorials linked, however. Did you not see them? IMHO it would be better to just link to the Open Directory Project, as was done in the Adobe Photoshop article, but consensus seems to be in favor of keeping selected links in the article. — mjb 07:35, 28 January 2006 (UTC)

Could someone re-write this sentence. I think it is little weird and might have to many comas. By leaving the names, allowable hierarchy, and meanings of the elements and attributes open and definable by a customizable schema, XML provides a syntactic foundation for the creation of custom, XML-based markup languages. --CyclePat 02:41, 28 January 2006 (UTC)

It is grammatically correct. But how about this: XML provides a syntactic foundation for the creation of custom, XML-based markup languages by leaving certain things — the names of elements & attributes, their allowable hierarchy, and their meanings — open and definable by a customizable schema. Personally, I don't like loading up a sentence with offset phrases and pronouns, though. — mjb 07:35, 28 January 2006 (UTC)
How about:XML leaves the names, allowable hierarchy, and meanings of the elements and attributes open. These are therefore definable by customizable schemas to suit various applications. In this way XML provides a single syntactic foundation for the creation of any number of custom, XML-based markup languages.
Then, re CyclePat's point, we could add: These custom XML languages can be tailored to meet a variety of needs, including
  • data transmission over the Internet,
  • local and remote information storage,
  • application-specific data and initialisation files and many other uses.
If well designed, these XML documents have the benefits of being
  • self-describing,
  • readable and editable by both humans and machines, and
  • interoperable with other XML applications especially by the use of XSLT transformations from one schema to another.
  • directly renderable in browsers using CSS
--Nigelj 13:16, 28 January 2006 (UTC)


in reply to MJG: I just had a little difficulty reading the original one yesterday. I'm part of the click generation. Instantanious gratification by clicking anywhere on a web page to get the answer. I re-read further up in the article and it finally came to me. Maybe the sentence could be cut in two sections, instead of re-wording, because I'm just as confused as I was the first time I read and I feel like I understood the original sentence. GOL. --CyclePat 13:26, 28 January 2006 (UTC)
In reply to Nigel: I like the table alot. It seems to make things a lot easier to understand. (ps.: I'm just getting into trying to understand this XML... I guess I should finish reading the article... when I don't understand something I tend to be less motivated to continue on. :o) Well, back to reading. --CyclePat 23:08, 28 January 2006 (UTC))

[edit] Are you defining an AT&T macro?

You had better come out and tell beginners what's wrong in your "Thing one...two" example.

AT&T:are you defining an AT&T "macro" for shortcut use later here? Beginners want to know.


[edit] IBM / Alphaworks is the biggest spammer of Wikipedia

We have links on their main sections, and on each pages of the sections. I propose to track them and remove most of the links.

Not all the links. Just leave links on main sections, and remove links on pages.

Boole

[edit] XPML

Somebody proposed to merge this stub into the article on XML. I'm not really at all familiar with the subject so could somebody more knowledgable take a look at it? Fightindaman 16:56, 6 March 2006 (UTC)

[edit] What, no mention of 1040?

Is it totally irrelevant trivia that XML is Roman numerals for the number of Form 1040? --194.226.235.251 07:12, 9 March 2006 (UTC)

Yes —Preceding unsigned comment added by Porge (talk • contribs) 20:26, 9 March 2006
I don't think that's correct. MXL would be the correct way to write 1040. --82.141.48.74 10:15, 23 December 2006 (UTC)

[edit] Anonymous Quote

The anonymous quote seems irrelevant and doesn't add anything to the article. Remove? 82.42.172.48 22:46, 1 April 2006 (UTC)

Yes. It seemed to attract several others in short order, all disparaging, anonymous, and unverifiable (except one which had a site listed). Come on, what's the case for having a section for quotes about XML in the article? "It has to do with XML" isn't good enough. Even if the quotes were clever and came from Tim Bray's mouth, it doesn't seem at all relevant unless it helps the reader better understand XML. I've gone ahead and removed them.—mjb 01:44, 9 May 2006 (UTC)

One of the quotes which I'd like to keep it's the "I'll use XML; then he has two problems" (the one referenced by dirtSimple.org). That quote is a play on a similar idea applied to regular expressions.

Why keep it? Because disparaging as it may be, it's a good way to remind us not to use XML just because it's there. It's a lost art in the programming world, I guess. —Preceding unsigned comment added by 193.137.7.4 (talk • contribs)

True, but reminding the reader of things is not what an encyclopedia article is for. Quotes fall under trivia ("someone once said…and it had something to do with <topic>") which just doesn't seem like a good use of the space, to me. I know you're eager to contribute, but you would probably do better to find some articles/blog posts critical of XML and make reference to them from the article somehow.—mjb 17:00, 10 May 2006 (UTC)
Or find a way to work it into the Weaknesses section? I think I got your point. Thanks 193.137.7.4 18:43, 10 May 2006 (UTC)

[edit] Isn't XML really a language for defining self-typing "type tags" for dynamic typing?

The entry for dynamic typing says "A typical implementation of dynamic typing will keep all program values 'tagged' with a type, and check the type tag before using any value in an operation." This is often refered to as "self-typing": "its type is explicitly stored in its representation" (see eg, www.ssw.uni-linz.ac.at/Teaching/Lectures/Sem/2001/Literatur/VosSpec.doc). Isn't this precisely one of the primary ways XML is used--to store a type "tag" for a data element in line with the element itself?

Isn't self-typing what is really meant by "self-describing"? Yet in a search for both "self-typing" and "self-describing" I could find only one article making this connection: If we consider the self-descriptive nature of XML documents, these paradoxes are less surprising than it may seem: XML documents use tags to delimit some content, and these tags can be considered as type information about the content they delimit. Therefore, XML documents--even those that do not contain a DTD--are in some sense "self-typed" constructions and this makes the definition of a type system for XML transformers difficult. [emphasis added] (see www-smis.inria.fr/%7Ebouganim/CASC/Publications/LRI-LIENS_ASIAN_2003_Information%2520flow%2520security%2520for%2520XML%2520transformations.pdf).

I think it would be worthwhile trying to highlight the relationship between XML (and descriptive markup languages generally) and the use of self-typing "type tags" for dynamic typing. This will shed greater light on XML in particular and markup languages in general. For example, thinking of XML as a way of representing self-typing data helps explain why dynamic languages are so popular in dealing with XML and why statically typed languages often suffer from "impedence mismatches" with XML.

I realize that what I am saying is implicit in much of what is written about XML, I am merely suggesting that this entry make it explict. --Nick 19:47, 10 April 2006 (UTC)

[edit] Inaccurate description in intro?

Languages based on XML...are defined in a formal way, allowing programs to modify and validate documents in these languages without prior knowledge of their form.

Isn't the form exactly what is known by the program, which can parse that which is defined in a formal way? Is this supposed to mean that the program can do it without knowing the actual content, only knowing the form? Or that it knows the XML form but not the sublanguage form? This needs to be more accurate and clearer. (Note also that "know" is not the correct term. Programs do not "know". Intelligences know, deterministic procedures do not.) - Centrx 06:36, 23 May 2006 (UTC)

[edit] Watch for spam tricks in external links

Stylus Studio is up to some new tricks, trying to get around the ban on XML editor links in this article (see above). They've created their own interface to the xml-dev list, replete with advertisements for their product, and changed the link for a more benign archive of the list. I've reverted this edit and encourage others to watch out for more edits like these. Verify any hostname changes in URLs.—mjb 04:01, 25 May 2006 (UTC)

[edit] XML Databases

I can't find any article discussing databases with XML as native data representation or as a model for their data access. The database related articles seem to focus on relational and object-oriented models and there is no notion of XML whatsoever. The only place that even distantly resembles it is the file processing part of this article. There already are notions of _some_ products using XML as their data representation model. However, it was removed as "inappropriate" when database product was mentioned in recent edit. Well, where it belongs then? The completely new article will be a very difficult task and I see no reason for "all or nothing" POV. Why not mention it somewhere in the main article with the hope that some day somebody will take it from here and further elaborate on this topic? 217.26.163.26 06:35, 14 June 2006 (UTC)

[edit] XML.com

A recent edit removed the link to XML.com, apparently on the grounds that it's a commercial site. So it is, but links to commercial sites aren't banned on Wikipedia, are they? Personally I have found XML.com very useful in learning about XML as it has many free tutorial documents on XML, XSL, SVG and related subjects. What do others think? Charivari 03:43, 19 June 2006 (UTC)

Thanks for the polite note. This is a frequently spammed article, and I removed the link because:
  • there are prominent ads on the front page of the site (at the top, on both the leftmost and rightmost columns, as well as a box in the third column);
  • much of the content on the front page is syndicated from a blog on another site (oreillynet.com), a frequent tactic of spammers;
  • the link was put into its own section ("Web-zines"), which is sometimes an indication of spam; and
  • there's actually still a link to a page within xml.com: Annotated XML Specification I think there's normally no need to include more than one link to a single site unless it's especially notable.
Of course, nothing above is indisputable evidence that the link must be removed. To answer your question, no, links to commercial sites aren't banned; it's a judgement call, and in my opinion the ads don't help the case for including this link. Maybe I was too hasty in removing it, though. I think it's significant that you find it useful, since you presumably don't have a vested interest in the site. Wmahan. 05:15, 19 June 2006 (UTC)
The advertisements are a nuisance, though the printer-friendly versions of the articles are almost free of ads. I've just checked one example to be sure: the long article "What Is XSLT?" has just a couple of ads for O'Reilly books on related subjects.
Your presumption is correct, my only interest in the site is as a source of information on this fascinating and very useful technology. And my interest in raising the point here is to ask whether the admitted disadvantage of linking to an ad-heavy site is outweighed by the benefits to Wikipedia users of an arguably very helpful source of information. My provisional view is that it is worth it, but I don't want to go against the consensus (if there is one, that is!). Charivari 05:55, 19 June 2006 (UTC)
I've re-instated the link. If anyone objects they can remove it again. Charivari 03:55, 22 June 2006 (UTC)
That's fine with me. You made a reasonable argument for including it. Wmahan. 04:40, 22 June 2006 (UTC)

[edit] Page moved

I've been so bold to move this page from XML to Extensible Markup Language. Most other software tech pages use the long name for the page title and not the TLA. --Ligulem 15:01, 25 June 2006 (UTC)


[edit] New XML Tutorial

I am the author of an XML tutorial called Caffè XML and I would like to add the link of the tutorial on the XML page of Wikipedia under the section Xml#External_links. However, I red on the Wikipedia official policy that self-published sources are largely not accepted with the exception of well-known professional researches in the relevant field. Hence, an idea is to let other editors familiar with the subject decide if it merits inclusion. This is why I wrote this post. You can find more about me (in particular, my teaching and research activity concerning XML) at my personal web page. M.franceschet 15:33, 29 August 2006 (UTC)

[edit] XML Strengths

81.69.42.175 09:30, 21 October 2006 (UTC) XML Strengths: the following strengths must be added (in my opinion) 1. XML supports your own schemas: XMLSchema

2. XML is extensible: you can add information to antother schema without being invalid

3. XML can be stored in Native XML Databases (sometimes even faster then relation data) (http://monetdb.cwi.nl/XQuery/)

4. XML can be queried by XQuery

5. XML supports transformations from one XML schema to antother using XSL (integration)



[edit] Nice picture

Maybe it would be good to create a picture similar to the figure "HTML_element_structure.png‎" from the article "HTML element" and include it near the top of this article. Such a figure would be really instructive. Ajgorhoe 23:24, 21 October 2006 (UTC)

[edit] Its simultaneously human and machine-readable format

Why in this world we need this? Do we ever read HTML file using text readers, like notepad?! —Preceding unsigned comment added by V4vijayakumar (talk • contribs)

All the time. — Jaxad0127 05:03, 8 November 2006 (UTC)
Me too. Reading and writing, (X)HTML, XML, XSLT, SVG, all using Notepad. (I'm not saying I'm any good at it!) Charivari 07:20, 8 November 2006 (UTC)
You forgot CSS, JavaScript, etc. I prefer Notepad2 (syntax hi-lighting and regex fid/replace). But its still source editing. WYSIWYG editors tend to give bloated code (especially word processors like MS Word). — Jaxad0127 17:33, 8 November 2006 (UTC)

[edit] XML Sucks

I'm not sure it is NPOV to have the title of a page entitled "XML Sucks" in the "Weaknesses of XML" section. What does everyone else think? Twipie 06:30, 19 November 2006 (UTC)

I don't see an NPOV problem per se - we're not endorsing the view, just referencing it as part of a discussion of strengths and weaknesses. The blunt title is more a devil's advocate thing anyway, since the page is a discussion, not a monologue.
What might be a good idea, though, is to introduce this better than "see also" - I know there's a whole "wiki solidarity" thing going on here, but really this should be part of a list somewhere (in External links?) of discussions about the pros and cons of XML. I'm sure we could soon get a large list of such discussions, so we'll probably have to be quite selective about it, but it would be better than one floating link. - IMSoP 12:59, 19 November 2006 (UTC)

[edit] (X)HTML Examples

I think using (X)HTML elements in the XML examples is a bad idea, as this will be confusing to people unfamiliar with XML.This is especially true when the examples makes explicit references to what is and is not valid in XHTML. The example with the script element is imo irrelevant to this article, and should be removed. Jerazol 20:01, 13 December 2006 (UTC)

[edit] XML data structure?

What is this stuff that's accumulating regarding expressing hierachical and relational data in XML vs doing so in relational/SQL databases[2]?

The way I understand it, XML is more flexible than relational or hierarchical data stores and can easily express either, both, and other things too. A valid criticism may be that it's too flexible, and allows people to misuse that flexibility; but what we have there at the moment seems fallacious.

For example, the films/actors relationship used as an example can be expressed in XML in many ways, including as follows. This looks like a fully relational many-to-many relationship to me:

...
<actor id="actor1">
  Bill Smith
</actor>
<actor id="actor2">
  Ben Brown
</actor>

<film id="film1">
  The Flowerpot Men
</film>
<film id="film2">
  The Revenge of the Flowerpots
</film>

<wasIn role="First Man" film="film1" actor="actor1" />
<wasIn role="Other Man" film="film1" actor="actor2" />
<wasIn role="Waiter" film="film2" actor="actor2" />
...

Whether this represents a backup or a document for any other use also makes no difference to the suitability of XML. --Nigelj 14:25, 17 December 2006 (UTC)

This is a fair point. However, the structure of this XML document does not reflect the relationships therein. These relationships do exist and can be specified, but it is not an inherent part of XML to specify them; it requires that the XML application (the program using the file) know that 'wasIn\@film' is an IDREF that links to a film element, and that 'wasIn\@actor' is an IDREF that links to an actor element.
The structure of an XML file is clearly hierarchical, following the hierarchical model. The structure of a relational database is relational. The fact that you can emulate relational structures through the content of an XML file is fairly irrelevant. One system is designed explicitly to handle relational information, and the other is not specifically designed for it. And that is the argument against using XML as a replacement for relational data. Korval 02:33, 10 January 2007 (UTC)

[edit] Document element

It's unclear from the text what is wrong with the "Document element" example given as an example of malformed XML. In fact, the root element in the example is identical to the root element in the example of good XML provided earlier in the article. Baudot 18:36, 22 January 2007 (UTC)baudot 10:36am PST, 22JAN07

The article says, a document "must have exactly one top-level root element". The malformed example has two "thing" elements at top level (i.e. with no overall parent encasing them both). That's not allowed. --Nigelj 19:37, 22 January 2007 (UTC)

Thanks for the explanation here. Perhaps this could be made more explicit in the text? As a reader learning XML from the document, my take on this was that the "<?xml version="1.0" encoding="UTF-8"?>" was the root element. It's non-intuitive that the "thing" tags are the root element. Perhaps changing the comment line to "<!-- WRONG! NOT WELL-FORMED XML! TWO THINGS-->" would be more clear? --Baudot 18:36, 22 January 2007 (UTC)baudot 10:36am PST, 22JAN07

Done. Thanks for the feedback, baudot. Good luck with your studies. --Nigelj 20:05, 22 January 2007 (UTC)

[edit] Requested move

Extensible Markup Language → XML — I have requested that this page be moved/renamed to XML. The abbreviation is far more commonly used than the spelled-out name. See Wikipedia:Naming conventions (acronyms). As with HTML and IBM, we should use the most commonly-used form as the page name, with the longer form as a redirect. If there's a consensus to rename or if nobody objects, an administrator will move the page in about 5 days. Kla'quot 03:56, 23 December 2006 (UTC)

We could have a poll about this if it's contentious, however I'd prefer to discuss rather than vote. Kla'quot 05:48, 23 December 2006 (UTC)

Change to XML per nom and what people would look for. Make this article into a re-direct. Hmains 19:41, 23 December 2006 (UTC)

Page moved, per unopposed request. Cheers. -GTBacchus(talk) 04:31, 28 December 2006 (UTC)