State of the XML Industry: In Perspective

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State of the XML Industry In Perspective
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Parand Tony Darugar
Binary Evolution Inc.
http//www.BinaryEvolution.com/
tdarugar_at_binevolve.com
C10 - State of the XML Industry
Parand Tony Darugar
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Overview
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What is XML?
Why Use XML?
How to Use XML
C10 - State of the XML Industry
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What is XML?
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eXtensible Markup Language
Tag, text based, similar to html. Alternatives
binary formats, database formats, etc.
Extensible applicable to new, disparate, differin
g domains
C10 - State of the XML Industry
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What is XML?
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XML is a standard for creating and storing
structured documents so that they are easily
processed and manipulated using off-the-shelf
components.
A markup language is a mechanism for identifying
structure in a document.The XML specification
defines a standard way to add markup to
documents.
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What is a Document?
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An XML document is generic
a document in the traditional sense, such as a
letter or a web page
a generic piece of information, such as a stock
quote, an EDI transaction, or a remote procedure
call.
XML can be used to express a diverse range of
information.
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XML Design Goals
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Easy to Use Over the Internet
Applicable to Wide Variety of Applications
Compatible with SGML
Easy to write XML Processors
Easy to create XML Documents
Human Legible
Minimum Number of Optional Features
XML Must be Expressable in EBNF
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A Sample XML Document
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ltstock-quote market"NYSE"gt
ltsymbolgtBINElt/symbolgt ltprice type"ask"
value"125.6875"/gt ltwhengt
ltdategt3/15/1999lt/dategt
lttimegt401PMlt/timegt lt/whengt
ltchangegt5.3lt/changegt ltvolumegt5412400lt/volume
gt lt/stock-quotegt
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What is XML?
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XML allows you to define a set of tags
appropriate to your domain.
XML does not define any particular set of
tags it is a system for allowing the user to
define her own set of tags.
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Comparison to HTML
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HTML defines a set of tags and the semantics, or
meanings, of those tags. XML does not define
any set of tags, nor the semantics for any tags.
It is a system for defining your own set of
tags. It is up to the user to define the
meanings and behaviors of the tags they define.
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Comparison to SGML
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Roughly, XML is a restricted form of SGML. XML
does not require Document Type Declarations, and
removes some of the less used and more
complicated features of SGML
SGML requires that the structure of the document
be completely defined in order to ensure the
document is valid. XML only requires that the
document be well-formed.
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Well Formed Documents
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For each begin tag, have an end tag
Use balanced tags, such that each begin/end tag
pair occurs inside another begin/end tag pair.
The elements, delimited by start and end tags,
must nest properly within each other.
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Document Type Definition
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A DTD is a grammar for a class of documents.
It defines which tags may appear in the
document, what their order must be, and what
their nesting rules are.
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Sample DTD
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lt!ELEMENT stock-quote (symbol, price, when) gt
lt!ATTLIST stock-quote market (NYSENASDAMEX)
"NYSE"gt lt!ELEMENT symbol (PCDATA) gt lt!ELEMENT
price (PCDATA) gt lt!ATTLIST price type (askbi
d) "ask" value CDATA IMPLIED gt lt!ELEMENT
when (date, time) gt lt!ELEMENT date (PCDATA)
gt lt!ELEMENT time (PCDATA) gt
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Parand Tony Darugar
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Why Use DTD's?
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DTD's are important in data exchange Parties
exchanging data must use a common, agreed upon
format. DTD's allow the specification of this
format.
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Validity
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DTD's define the exact structure and layout of
the document. They allow the user to verify that
the document is of the correct type, and
contains the appropriate fields.
An XML document which is verified against a DTD
is said to be Valid.
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Why Does XML not require DTD's?
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DTD's can be difficult to create
DTD's allow checking of document structure by
the parser. XML puts this responsibility onto
the application.
The parser can perform well-formedness checking
without a DTD.
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Displaying XML
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If XML does not contain any display information,
how do you display it? XSL, the stylesheet
standard for XML, allows you to define display
characteristics for XML documents. It allows you
to define how each tag should be rendered, as
well as allowing large scale manipulation of the
document, such as re-ordering elements.
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Parand Tony Darugar
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Applications of XML
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Replacement for HTML
Data Exchange
Data Storage
Many, many specialized applications
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Why XML over HTML?
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Expresses content and structure of document as
opposed to display information.
Imagine trying to find the trade volume for a
stock from a stock quote in HTML - It's a
manual process. In XML, you simply look at the
ltvolumegt tag.
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Parand Tony Darugar
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XML advantages
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Imagine trying to create a recipe book from
all the recipes on the Internet. With HTML, each
recipe is described in terms of how it is
displayed, making it very difficult to isolate,
for example, the ingredient list. With XML, if
all recipes used the same DTD, it would be very
simple.
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Parand Tony Darugar
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Current uses of XML
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In browsers - IE 5.0, Netscape 5.0 Chemical,
Bioinformatic, Weather Observation, ... EDI,
Financial, Trading, Banking protocols Real
Estate, Automotive, News Distributed objects, RMI
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Parand Tony Darugar
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Example XML in Real Estate
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OpenMLS defines a format for the storage of Real
Estate information in XML. Using this format,
Real Estate information can be exchanged between
different agencies, and precise searching based
on fielded information is possible.
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Parand Tony Darugar
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Using XML
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Browsers support for XML is here, and
rapidly improving. XML is supported in most of
today's popular programming languages. A host of
tools, editors, application servers,
and middleware is being created to handle XML.
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XML Support in the Browser
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Internet Explorer 5.0 supports XML as well as XSL
stylesheets. It is possible to view an XML
document with the current (March) release of the
browser. Netscape will include XML support in
its next release, and early indications are that
the support will be very good.
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XML Editors
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Many of the existing HTML editors and web design
tools are being updated with XML support. SGML
editors are being modified to work
with XML. Many popular applications, such as
Microsoft Office, and a host of others, will be
able to save as XML in future releases.
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Language Support for XML
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XML Parsers exist for most popular
programming languages
Java - Several parsers exist, including offerings
from Sun, IBM, and the free software
community. C, C -Expat, Microsoft, etc. Perl
- XMLParser Tcl - TclExpat,
TclXML Python - Python/XML Many others...
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XML Programming
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The XML Parser parses the XML document, leaving
the user with the task of handling what should
happen for each tag. There are also facilities
for creating tree representations of the
document, such as DOM, which allow the programmer
higher level access to the document.
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XML and Databases
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XML can be, and often is, used in conjunction
with databases The database stores, retrieves,
and performs searches on the data. Data is
received into and served from the database as XML.
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XML Tools Databases
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Databases - Most of the major databases have
already released XML capable versions, or will
be shortly. Object Oriented Databases can be
used effectively for storing XML documents, and
several products exist as storage and retrieval
solutions for XML.
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Parand Tony Darugar
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Web Middleware for XML
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Application servers are adding XML support, with
some products already available on the market.
These products will enable and facilitate the
creation, storage, retrieval, and exchange
of XML on the web.
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State of XML Today
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The XML standard is mature, enjoys a great deal
of support among vendors and users, and is being
used to deploy real world applications. XSL, the
stylesheet standard, is nearing maturation, but
still in development. Programming interfaces,
such as DOM, and SAX, are in use today, and
undergoing active development.
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Parand Tony Darugar
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State of Tools
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Vendors have embraced XML and have released or
announced support for XML in their tools. The
tools market will change as XML
doployment becomes more common and patterns
emerge for XML usage and programming. More
graphical, easy to use tools will appear to
allow XML use for less technical users.
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Parand Tony Darugar
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What it will Take to Succeed
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Document formats (DTD's or one of the
alternatives) need to be defined for many classes
of documents, to allow wide spread usage of
XML. Initially, DTD's for specific industries
will be defined, and XML will be deployed in
those particular fields. XML is a technology it
may enable the next killer app, but is not the
next killer app.
C10 - State of the XML Industry
Parand Tony Darugar
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XML Resources
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www.binaryEvolution.com/tdarugar/ This
presentation, updates, and more. XML.com -
Information and news www.w3.org/XML - W3C XML
pages XMLToday.com - news, tools, and sample
document
C10 - State of the XML Industry
Parand Tony Darugar