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http://www.oracle.com/technology/oramag/oracle/06-jul/o46field.html
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COMMENT: In The Field XML in Databases XML's usefulness multiplies with
proper handling. In a world of
competing proprietary data formats, XML is a neutral and generalized format
that is ideal for data exchange. It is especially suited for applications
employing service-oriented architectures (SOAs),
because to simplify reuse of program components, the individual services need
to send and receive data in general formats. XML data includes tags
that can describe the data, including its formatting and uses. You can also
use built-in security precautions with XML, including encryption and
authentication features. Plus, the format is extensible—the X in
XML—so that you can define new formats for new data for new
applications. XML-format data
presents both challenges and opportunities for databases. The challenges are
obvious: A data item in XML format takes up more room in storage because you
have to accommodate all those descriptive tags that come along for the ride.
In addition, databases may need to perform extra processing to import and
export in XML format. The opportunities are
more subtle and available only with databases that store XML in its native
format, such as the Oracle XML Database. For example, because each data item
has its own descriptive tag, versioning is possible, allowing you to examine
successive changes to data. Those tags also make intricate searches through
data possible. The Business Problem To illustrate when to
use XML, consider a project I participated in with a large financial trading
institution—300 employees, 5,000 concurrent users, millions of
transactions a day, and more than US$160 million in revenue. Before the market
opens, incoming data includes premarket orders.
During trading hours, real-time financial information flows into and out of
the company. Then when the market closes, the end-of-day processing begins,
including generating reports on the day's trading activity. The problem? How to
share information with a diverse audience—partner companies and news
media—that used different applications and information. The company had
been using flat-file information to provide service to customers and
partners. The Solution We elected to use XML
to send data to the news media: XML's data tags
provided the context necessary to define the enclosed information and served
as useful input for automatic processing to news feeds. We also used XML to effect company-to-company data transfer. By contrast, we
did not use XML for financial transactions because of concerns about both
security and processing speed. The challenge was to
deliver the XML solution on time and within budget to provide that better
information service. We managed to do that, and as a result, the company can
now communicate with a broader audience—even though each recipient has
its own applications and formats. The company sends information out once in
one format and no longer needs to scramble to match communications with
customers and juggle multiple, ever-changing formats.
Another example of a
corporate project I contributed to is the popular
Web site of a company with 18,000 employees and more than US$4 billion in
revenue. The site presents product information to potential customers.
Manufacturers provide the site with detailed information on the products and
their features. Local dealers supply information on which products, with
which features, they have available to sell. Visitors to the site generate
lots of queries, searching for specific products or features and comparing
all the different products. The site had
originally used a proprietary data format that partners had to adhere to,
which limited the site's growth and partnership opportunities. Switching to
XML allowed the company to provide information consistently to a wide range
of audiences and applications. The information flow between the local dealers
and the Web site was entirely in XML format. This setup made it
simpler for the many dealers—using a variety of their own internal
applications—to provide their information and receive results and data
from the site. As a result, it's now easier to scale up the site for the
partners, who enjoy smoother growth and thus are better satisfied. The site
data was all stored in the usual tables in an Oracle database. XML is not for
every use or occasion. But when you need flexibility and neutrality, it can
be ideal. Ari
Kaplan (ari_kaplan@ioug.org)
is president of the IOUG (Independent Oracle Users Group) and senior
consultant for Datalink. He founded Expand Beyond Corporation, a leader in
mobile IT software. He has been involved in Oracle technology since 1992. |
