submit client request before http redirect

You can detect logout uri in HTTP_REQUEST and redirect in HTTP_RESPONSE

when HTTP_REQUEST {    
    if {[HTTP::path] equals "/logout"} {        
        set logout 1            
    } else {        
        set logout 0            
    }            
}       

when HTTP_RESPONSE {        
    if {$logout} {        
        HTTP::redirect /foo            
    }
}