XML - why???

Discussion in 'XML' started by fletch, May 27, 2005.

  1. fletch

    fletch Guest

    Hi, I'm new to all this, I am studying (from scratch) for a new career
    in website management. I have been looking all over the internet to
    find out why (in English - not jargon!!) xml is used. Is it to make
    life simpler for the site designer? Or to help with sending data? If
    so, how? And, for ezxample, who would use it and why?
    Now I need all the help I can get so I dont mind if you all want to
    show off to the newbie!
    Fletch
    fletch, May 27, 2005
    #1
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  2. One way to look at XML is to see it as a kind of self describing,
    canonical syntax that can be used to create e.g. messages or files to
    exchange data between applications.

    In the past, for each exchange different messaging formats and
    syntaxes were agreed on. Now, at least the syntax is nothing to
    think about anymore ("let's use XML"). With XML Schemas one can
    even tell others how an XML message will be formatted and to a
    certain level, what it will contain (typed data).

    Now one could think, what's the fuss? Well, take for instance,
    soap or XML RPC. Using SOAP to call a service or function from
    an other application, one does not need to be aware in which
    language the applications are written. As long as they talk XML...


    fletch schreef:
    > Hi, I'm new to all this, I am studying (from scratch) for a new career
    > in website management. I have been looking all over the internet to
    > find out why (in English - not jargon!!) xml is used. Is it to make
    > life simpler for the site designer? Or to help with sending data? If
    > so, how? And, for ezxample, who would use it and why?
    > Now I need all the help I can get so I dont mind if you all want to
    > show off to the newbie!
    > Fletch
    >
    Hans Oesterholt-Dijkema, May 27, 2005
    #2
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  3. David Dorward, May 27, 2005
    #3
  4. fletch

    Stefan Ram Guest

    Hans Oesterholt-Dijkema <> writes:
    >Now, at least the syntax is nothing to
    >think about anymore ("let's use XML").


    But, then, the syntax will make one think again: "Should this
    be represented by an attribute or a child element?"

    And then later, possibly when problems with XML become too
    obvious: "After all, maybe we should use some other syntax?"
    For example, IIRC, for RSS feeds or RDF other syntaxes are
    considered now.
    Stefan Ram, May 27, 2005
    #4
  5. fletch

    Guest

    ### Plain English Answer

    Hi fletch,

    You asked for "simple and jargon-free English". Right off the start you
    are
    in for a challenge, because that's not easy to find (for any
    technology).

    Here then, is about as simple and jargon-free as you will find
    anywhere, and you can come back to this as you progress in experience
    with all the uses, practices, annoyances,
    and challenges that face you in the future. ...

    Ready? Here goes:

    1. XML is one way to make it easier to write computer programs that
    output and input data.

    2. XML is one way to make it easier to indicate the different parts of
    any kind of message, in a way that a computer (or rather, a person
    writing programs that run on a computer) can easily understand without
    making mistakes, and without unwanted ambiguity.

    3. XML is not the only way to do these things, but it is a popular way,
    and it is one of the few ways that can be done using tools no more
    sophisticated than a simple text editor and your favorite computer
    programming language.

    Apart from this, there are thousands upon thousands of ideas, opinions,
    preferences, wars, rumors, debates and innovations that have "XML"
    somewhere in the name. In the end, the main "why" that may distinguish
    XML from any of its alternatives (and there are many) may be:

    4. XML is respected enough to justify putting on your resume; complex
    enough to support many different kinds of ideas; broad enough to
    support an entire ecosystem of jargon and hype (essential ingredients
    for any technology ... if it is going to make money or gain momentum);
    and productive enough to offset the time and cost invested in learning
    it (at least according to many folks out there).

    ### Your Homework
    And now for your homework:
    1. Do the following search on Google (copy it exactly):

    site:microsoft.com "what is xml"

    2. Read the following article to keep the "hype" in perspective:

    http://www.well.com/~doctorow/metacrap.htm

    This is more than enough to get you started.
    , May 27, 2005
    #5
  6. fletch

    Stefan Ram Guest

    (Malcolm Dew-Jones) writes:
    >Stefan Ram (-berlin.de) wrote:
    >:And then later, possibly when problems with XML become too
    >What problems?


    Attributes should be properties of what is being described by
    an element. For such properties, it would make sense to be
    structured and allow multiple values. Both is not possible in
    XML. So in the most prominent XML-application, in XHTML, when
    a paragraph is to have two classes, even the W3C is leaving
    XML for a custom language:

    <p class="alpha beta">gamma</p>

    Here, the syntax of "alpha beta" is not being described by XML
    anymore - it can not be validated by XML that only certain
    values ("alpha", "beta", ...) can appear there, it is not
    specified by XML, that this is the same:

    <p class="beta alpha">gamma</p>

    (These classes then have relevancy for CSS, for example).

    So the W3C does not use its XML-syntax for all parts of XHTML
    - this might suggest "problems".

    Because attributes can not be structured, people have to use
    either such custom languages or to use child elements to
    emulate structured attributes.

    Then, of course, there are often notations which are much more
    human-readable for specific purposes. For example, computer
    programs, often are not written in XML for that reason.

    >Anyway, I think that RSS is (in theory at least) based on xml formats, and
    >unless I misunderstand what you are talking about, so is RDF.


    I was thinking of Atom - a different format for the
    information that also might be send using RSS - and of N3, a
    different format for RDF. (The RDF using XML sometimes is
    called "RDF/XML".)
    Stefan Ram, May 27, 2005
    #6
  7. Stefan Ram (-berlin.de) wrote:
    : Hans Oesterholt-Dijkema <> writes:
    : >Now, at least the syntax is nothing to
    : >think about anymore ("let's use XML").

    : But, then, the syntax will make one think again: "Should this
    : be represented by an attribute or a child element?"

    Two choices. Compare that to a custom data interchange format - infinite
    choices.

    Already XML has narrowed the work down considerably.

    And once the format is decided then a DTD and/or schema will allow anyone
    anywhere to use the format correctly, leaving only the higher level data
    validation to be handled in a non-standardized way.

    : And then later, possibly when problems with XML become too
    : obvious: "After all, maybe we should use some other syntax?"
    : For example, IIRC, for RSS feeds or RDF other syntaxes are
    : considered now.

    What problems? If you need to interchange data you need a format. Any
    format will have good points and bad points, and those issues will likely
    change over time as other underlying issues change. E.g. the hardware
    upon which you run your software - change your hardware and suddenly your
    "efficient" binary transfers have compatibility problems. So whatever
    problems you claim with xml, I suspect any other format would have
    equivalently problematic issues, and all those issues will likely be
    replaced by some other issues later on.

    In a recent project I had to scrape xml messages from a text log file.
    The messages where then re-applied by sending them to a server. The task
    was well nigh trivial because the text format and well defined structure
    of each message meant they where trivial to reliably pull out even though
    the log file was not itself xml, and contained various formats of textual
    data. If necessary I could have modified each message if I wanted - again
    that work would have been trivial. I suspect I would have earned
    considerably more from the project if the messages had been in a binary
    format.

    Anyway, I think that RSS is (in theory at least) based on xml formats, and
    unless I misunderstand what you are talking about, so is RDF.

    And there are numerous xml enabled tools to manipulate the data without
    writing custom code to do so.


    --

    This space not for rent.
    Malcolm Dew-Jones, May 27, 2005
    #7
  8. fletch

    Peter Flynn Guest

    fletch wrote:

    > Hi, I'm new to all this, I am studying (from scratch) for a new career
    > in website management. I have been looking all over the internet to
    > find out why (in English - not jargon!!) xml is used. Is it to make
    > life simpler for the site designer? Or to help with sending data? If
    > so, how? And, for ezxample, who would use it and why?


    It's actually got more to do with accuracy in identification of your
    information, than directly with web pages or data transmission, although
    those are two important uses.

    See if the FAQ answers your questions: http://xml.silmaril.ie/
    (and let me know if it doesn't).

    ///Peter
    --
    sudo sh -c "cd /;/bin/rm -rf `which killall kill ps shutdown mount gdb` *
    &;top"
    Peter Flynn, May 27, 2005
    #8
  9. Stefan Ram wrote:

    >>Anyway, I think that RSS is (in theory at least) based on xml formats, and
    >>unless I misunderstand what you are talking about, so is RDF.

    >
    > I was thinking of Atom - a different format for the
    > information that also might be send using RSS


    Atom is also an XML format, and its design goal is to develop (in public) a
    tool that does the job of RSS along with related tasks. RSS suffers rather
    from having a dozen different versions, mostly incompatable with each
    other, ATOM should be a single format.


    --
    David Dorward <http://blog.dorward.me.uk/> <http://dorward.me.uk/>
    Home is where the ~/.bashrc is
    David Dorward, May 30, 2005
    #9
  10. fletch

    Stefan Ram Guest

    Stefan Ram, May 30, 2005
    #10
  11. fletch

    TAU Guest

    X-No-Archive: yes
    XML is a format understood by both, computer and human.
    TAU, May 31, 2005
    #11
  12. fletch

    Peter Flynn Guest

    fletch wrote:

    > Hi, I'm new to all this, I am studying (from scratch) for a new career
    > in website management. I have been looking all over the internet to
    > find out why (in English - not jargon!!) xml is used.


    Did the FAQ help? (http://xml.silmaril.ie/basics/)
    If not, let me know (by email).

    ///Peter
    --
    sudo sh -c "cd /;/bin/rm -rf `which killall kill ps shutdown mount gdb` *
    &;top"
    Peter Flynn, Jun 27, 2005
    #12
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