Application front-end code
Runs on front-end interface bricks
Accepts requests from LAN/WAN connection
- Incoming requests made using standard high-level protocols
Invokes and coordinates appropriate worker code components that execute on internal blocks
- Takes into account locality and load balancing
- Database: front-end performs SQL query optimization, invokes distributed relational operators on data storage devices
- Transformational proxy: front-end invokes distiller thread on appropriate device brick
- if data is cached, invoke on disk node
- otherwise, fetch data from web and invoke on compute node or disk node