An Exposed ESB Gateway node makes the services of one organization available to others, and vice versa, in a controlled and secure manner. Although this might require capabilities such as partner provisioning and management, which are distinct from ESB capabilities, the intent of this component is different from the intent of the ESB, which is to provide a service infrastructure within an organization. For both these reasons, the Exposed ESB Gateway is likely to be integrated to, but not be a part of, the Enterprise Service Bus.
The connection between the app service/services node in the partner zone and the network infrastructure in the inter-enterprise zone could be an HTTP server, an ESB, an Exposed ESB Gateway, or a firewall. Therefore, depending on security requirements, the Exposed ESB Gateway node can be inside or outside of the Enterprise Demilitarized Zone.