Measuring the Capacity of an XML Schema: Specifying an Information Channel with an XML Schema
Fundamental concepts for measuring the amount of information specified by an Extensible
Markup Language (XML) Schema are presented. A web service or XML application can use an
XML Schema to specify the form of XML data allowed to invoke the service or application. The
XML Schema may be viewed as a specification of an information channel to the web service or
application. The capacity of the information channel specified by the XML Schema can be
numerically measured.
Knowledge of the capacity of a channel specified by an XML Schema is beneficial for web
services and XML applications. The capacity indicates how much effort might be required by a
web service or application to process XML instances, thus serving as an indicator of the potential
load on the web service or application.
Knowledge of the capacity of a channel specified by an XML Schema is also beneficial for
security services that regulate against undesirable information exchanges. The amount of
regulation required is proportional to the variety of information received. Thus, XML data
conforming to an XML Schema that has a large capacity will require a comparatively large effort
to regulate. As a general rule, the higher the capacity, the larger the security risk.
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