A number of brands of XML Firewall exist and they often differ based on parameters like performance (with or without hardware acceleration, 32 Vs 64 bit), scalability (how do they cluster and perform under load), security certification (common criteria, FIPS being the most common), identity support (for SAML, OAuth, enterprise SSO solutions) and extensibility (they can support different transport protocols like IBM MQ, Tibco EMS, etc.).
XML | XML Schema (W3C) | XML Schema | Simple API for XML | XML schema | XML Information Set | Plain Old XML | XML database | XML validation | XML User Interface | XML Resource | XML Professional Publisher | XML namespace | XML Database | XML-binary Optimized Packaging | .XML | .xml | Stateful firewall | SQL/XML | Open XML Paper Specification |