# Load the module into your server:
LoadModule parp_module   /mod_parp.so

# activate mod_parp for all requests matching the URL /a /b but not the URL /a/upload:
SetEnvIf   Request_URI   ^/a.*            parp
SetEnvIf   Request_URI   ^/a/upload.*    !parp
SetEnvIf   Request_URI   ^/b.*            parp

# suppress content types not supported by mod_parp:
SetEnvIf   Content-Type  text/plain      !parp
SetEnvIf   Content-Type  text/xml        !parp
SetEnvIf   Content-Type  text/html       !parp