WebSphere Application Server V7.0: Concepts ... - IBM Redbooks

SIP proxy
The SIP proxy design is based on the HTTP proxy architecture. The SIP proxy
extends the HTTP proxy features. It can be considered a peer to the HTTP proxy.
Both the SIP and the HTTP proxy are designed to run within the same proxy
server and both rely on a similar filter-based architecture for message processing
and routing.
The SIP proxy server initiates communication and data sessions between users.
It delivers a high performance SIP proxy capability that you can use at the edge
of the network to route, load balance, and improve response times for SIP
dialogs to back end SIP resources. The SIP proxy provides a mechanism for
other components to extend the base function and support additional deployment
scenarios.
The SIP proxy is responsible for establishing outbound connections to remote
domains on behalf of the back end SIP containers and clients that reside within
the domain that is hosted by the proxy. Another important feature of the SIP
proxy is its capability to protect the identity of the back end SIP containers from
the SIP clients.
WebSphere Application Server Proxy provides many functions that Web server
and plug-in have but it is not a full replacement because it does not have Web
serving capabilities. (Static content can be served from the proxy cache) If the
Web server is used only for load balancing and routing with session affinity,
WebSphere Application Server Proxy can take the place of the Web server.
WebSphere Application Server Proxy is not considered a secure proxy for
demilitarized zone (DMZ) deployments. For example, it cannot bind to protected
ports without being a privileged user on most operating systems and users
cannot be switched after binding. WebSphere Application Server Proxy must stay
in the intranet/secure zone.
DMZ Secure Proxy Server
As the WebSphere Application Server Proxy is not ready for a DMZ, WebSphere
Application Server V7.0 ships a DMZ-hardened version of WebSphere
Application Server Proxy. The DMZ Secure Proxy Server comes in a separate
install package that contains a subset of WebSphere Application Server Network
Deployment and provides new security enhancements to allow deployments
inside of a demilitarized zone (Figure 3-11 on page 69).
68 WebSphere Application Server V7.0: Concepts, Planning, and Design