Path Instantiation and Implementation
Before building physical path, each logical path is assigned a unique PathID.
Instantiator
- Given a logical path, create a physical path by choosing specific machines to run each of the operators.
- Rule: If an operator is uploadable, upload it onto the machine running the path (if possible).
- Requirement: Uploadble operators still must be running somewhere; uploading is for efficiency, not availability.
Implementer
- Given a physical path, start that path running on each of its operators
- Set up connectors (streams) between operators
- Begin a new thread on each operator which will perform operation for data associated with this path
Theme: Bind and fast access
- Path set-up is relatively costly, but little overhead is imposed on transmission.
- No RMI or control path calls required unless a failure occurs.