Here's an interesting article on XML Gateways, their use in SOA deployments, and a comparison between hardware, software and cloud-based form factors. SOA Tester have to be cognizant of identity, encryption, and signature artifacts that are consumed and generated by XML Gateways so as to build proper test cases for comprehensive end-to-end SOA testing.
Tale of Two XML Gateways
— These days XML Gateways are a core infrastructure component of any enterprise SOA deployment. XML Gateways provide the ability to integrate services securely with granular access control, data-level encryption, integrity through signatures and XML threat mitigation. XML Gateways can be deployed as a hardware appliance or as a software gateway. Both these form factors have their advantages and disadvantages. This article provides readers a quick synopsis of the advantages and disadvantages of each form factor.