HP is involved with IBM, Oracle, Sun and Bowstreet in developing a standard
to make web transactions standard across multiple vendors.  Here are some
snippets from the www.xaml.org web pages:

"Transaction Authority Markup Language (XAML) is a vendor-neutral standard
that enables the coordination and processing of online transactions in the
rapidly emerging world of XML web services - the revolutionary new model of
Internet-based computing that is now being adopted by all major systems and
software vendors. XAML is intended to be a completely open standard for
web-based business transactions.

The standard defines a set of XML message formats and interaction models
that web services can use in order to provide business-level transactions
that span multiple parties across the Internet.

XAML is not owned by any one vendor. Instead, the standards proposal will be
submitted to an appropriate open standards body to ensure that it remains an
open industry standard in which any interested companies and organizations
can participate."

"The new standards initiative is called XAML, for Transaction Authority
Markup Language. The XAML initiative is so named because it is an
application of XML (the common language of e-commerce) that defines
transactional interaction among web services, based on interfaces as defined
by the widely adopted XA (Transaction Authority) standard and by JTA (Java
Transaction API)."

"Bowstreet, Hewlett-Packard Company, IBM, Oracle, and Sun Microsystems plan
to submit the XAML proposal to an appropriate open standards body to ensure
that it remains an open industry standard."

http://www.xaml.org/documentation.html