The enterprise database infrastructure today consists
largely of high-end transaction processing systems such as Adabas and IMS
on one hand and RDBMS-based information systems on the other.
Over the last five years, however, there has been an
explosion of demand for access to these enterprise databases over the
internet, and also to use them to support electronic business operations.
These include transactions between systems within an enterprise
("enterprise integration"), between businesses in a supply chain
("B2B e-commerce") and directly to customers ("B2C
e-commerce"). The initial reaction of most companies was to integrate
these diverse operations by building or buying software such as
"application servers" that employed protocols such as DCOM or
CORBA to perform such integration. More recently, XML offers the option of
performing the necessary integration by exchanging standardized data.
Why is this, and what about XML has changed the situation?
The SQL standard defines a vendor-neutral way of finding and extracting
data from an RDBMS, so it is quite possible to write middleware
applications that extract data from one database and put it in another.
Nevertheless, these applications must be relatively complex and pay
careful attention to the database schemas on each side in order to work
properly. XML, on the other hand, is simply a standardized
"meta-format" that can represent any kind of data, and for which
precise schema definitions are optional.
Thus, XML has become widely used to integrate enterprises,
supply chains, and Web applications because it is:
-
Standardized - Many products from many vendors
are available that implement something close to the World Wide Web
Consortium Recommendation on XML.
-
Simple - the technology is easy to learn and
implement, with many tutorials and "how to" books available.
-
Self-describing - straightforward data exchange
applications can be written without reference to detailed format
descriptions or schemas.
So, XML is redefining today's database infrastructure by
serving as the "glue" that binds diverse enterprise systems to
each other and to the internet.