The first XML appliances were created by DataPower and Vordel in 1999, Sarvega in 2000, Forum Systems in 2001, Managed Methods in 2005 and Layer 7 Technologies in 2002.
Early vendors like DataPower focused on the XML acceleration problem which they solved through specialized hardware.
While several vendors like DataPower (purchased by IBM in 2005[1]) and Layer 7 Technologies continue to offer hardware accelerated options for high performance situations, advances in computing speed has made software or vmware based "appliances" practical in many common customer situations.
Early use cases for XML appliances included banking and cross-agency government information sharing.
Appliances became a popular way of controlling or governing SOA because addressed message security, availability and translation of data so that an application can call another application irrespective of the data format and security policies.