Each worker node can host several cloned Extract servers running on different ports. Each server can serve multiple clients in different threads, the only limitation is CPU and memory. Extracted files are copied to appropriate (AFS) directories as requested by ELSSI (using xrootd server is under consideration). Worker nodes are currently running on lxvm0341 and voatlas18.
Extract manager manages Extract servers on worker nodes. It can start new server clones, monitor execution, etc. It dispatches extraction requests to concrete Extract servers. Extract manager communicates with Extract servers using Python scripts and XML fragments over XML-RPC connection. Extract manager can be accessed via a command line (athenaeum command) or using GET or POST command over HTTP connection (when it is deployed on suitable container - J2EE/Tomcat, etc.). Extract manager is currently deployed on CERN J2EE Server.
ELSSI accesses extraction service via Extraction manager. It can also access an Extract server directly, but that would by-pass management layer and could have problems to pass through firewalls.
User accesses extraction service via ELSSI service. She can access it also directly using a command line interface or Extract manager URL (for testing purposes, etc.).