security token exchange module for Apache 2

 A security token exchange module for Apache HTTP Server 2.x which allows for
 exchanging arbitrary security tokens by calling into a remote Security Token
 Service (STS).
 .
 This Apache module allows for exchanging a security token (aka. "source
 token") that is presented on an incoming HTTP request for another security
 token (aka. "target token") by calling into a Security Token Service (STS) and
 then include that target token on the propagated HTTP request to the content
 or origin server.