Webservice Gateway

Webservice gateway is infrastructure component for webservices architecture. It provides single point of control for the webservice invocation.

It is nothing but soap processing engine that focuses on operation for intermidiatery for soap processing chain. It provides location transparency for service providers from webservice consumers

Alternately it provides following functionalities

1. Alter the destination of a message (routing)
2. Handle custom header tag processing
3. Apply and remove message level security (WS-Security)
4. Perform protocol transformation, for example, submit incoming SOAP/HTTP messages to SOAP/JMS

IBM websphere Security gateway is a Web services infrastructure component that is packaged with the WebSphere Deployment Manager

Please see following link for more details

http://www.ibm.com/developerworks/webservices/library/ws-routing/