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 eXtensible
Markup Language (XML) has been a key element facilitating
organisations in their move on to the Web. But another aspect
of the technology that has not been sufficiently tapped has
been its ability to integrate data. Kunal Pole analyses
the language and finds out how it helps in the integrating
applications and data
With
practically every business moving on to the Net, HTML or Hypertext
Markup Language hardly needs an introduction. Markup implies
adding some additional meaning to textual information. The
simplest form of markup could be that of highlighting areas
in a document to enhance importance. The process has two areas,
identifying the text for special meaning or code and its interpretation
by its consumer.
Markup or coding of text documents have a long history of
few decades with the first draft standard named as Structured
Generalised Markup Language (SGML) in the eighties. All current
markup languages are either a subset of SGML or applications
of SGML.
XML or eXtensible Markup Language is a subset of SGML providing
ease of use to define and interpret text areas as per requirement.
The flexibility of defining text areas with interpretation
based on user requirement, is the biggest advantage of XML.
The most common form of identifying text areas is enclosing
the text inside what is called as tags. For example <B>TEXT</B>,
the tag <B> here can be interpreted as Bold or Big letters
by a word processor. The application will read the tag and
apply the meaning attached to it to display or interpret it.
This simplicity enables markup languages to be used to format
text files for display, like in HTML, or define data in a
flexible way—as in XML. XML is a flexible way of defining
text in a way that is useful for data exchange. This is important
in view of computer applications.
Take an example of a common document like Purchase Order.
For us, interpreting a PO is straightforward—items, quantity,
rate, total, terms, etc. But to applications on both sides
of an organisation, it’s difficult to map one to one
without causing problems. The price may be referred to as
amount between organisations. Adding to it, if the formats
are in plain text, it becomes more difficult to scan through
the whole document (termed as parsing) to sense key information
items. XML handles this problem well with the use of self-describing
text documents that can be validated against the particular
organisation’s specification.
Consortiums like Rosettanet have managed to provide a master
dictionary of business document specification along with its
implementation guidelines to make it useful. Every element
in the document can be accessed with standard parsing programs
so applications are easy to build.
Many trading sites like Commerceone.net provide XML-based
interaction between suppliers and buyers. Infrastructure support
for implementation of interaction with parties using XML is
strongly moving ahead. The ebXML initiative from OASIS, which
is being driven by the United Nations and supported by industry
leaders, provides such specifications for global use. These
XML-based specifications enable enterprises of any size and
in any geographical location to conduct business over the
Internet. Using ebXML, companies now have a standard method
to exchange business messages, conduct trading relationships,
communicate data in common terms and define and register business
processes.
The use of XML is not limited to business documents alone.
The easy to read and self-describing text format can be put
to use in a variety of applications. Almost all of the new
releases of industry strength databases support XML as one
of the exchange formats. Use of XML for storing configuration
settings for applications is also becoming very common.
On the presentation side, data defined in XML can be easily
made presentable on multiple devices from phones and PDAs
to standard Internet browsers. The same set of information
can be displayed in a variety of formats. The device support
is coming up to a level wherein the way particular information
is displayed on a device will be based on the XML device profiles
made available by device manufacturers. Industry leaders like
IBM, HP, Microsoft, Sun, etc. are providing excellent tools
and infrastructure for next generation Internet and Web services.
Web services rely heavily on XML to define interfaces and
contracts to enable applications discover and use business
functionality over the Internet.
The biggest impact of XML can be seen in integrating heterogeneous
applications inside and across organisations. Traditionally,
applications tend to evolve around the key needs of organisations.
They also depend on the appropriate technology available at
that point of time.
Integrating such applications becomes a nightmare because
of the disparity in accessing functionality between, and lack
of a common data exchange format. The ERP boom in the industry
aimed to satisfy this need, however since all the modules
were not implemented in one go—thanks to the unsuitability
of some processes for the organisation and need for costly
customisation and licensing—this attempt at integrating
applications too fell flat.
XML: The preferred choice
Today, XML is the preferred way for Enterprise Application
Integration (EAI). These applications make use of XML as standard
format for information exchange. The middleware or ‘bridges’
provide functionality for converting existing data or application
interfaces into XML format. This along with the use of common
network protocols for exchange provides easy interfacing of
applications inside or outside organisations. This takes organisations
beyond the portal approach, where normally, sharing of information
is done through third party websites not in their control.
Any legacy functionality inside an application can be exposed
for use to form a part of bigger chain in the new economy.
XML has really touched all aspects in the computer world and
is poised to be very effective particularly in application
areas involving connectivity and integration with communities
of dealers, suppliers, banks etc.
The author is associate technical
manager, Persistent eBusiness Solutions
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