Support for continuous media.
Streams in distributed systems
All communication facilities discussed so far are essentially based on a discrete, that is time-independent exchange of information
Characterized by the fact that values are time dependent:
d. Sensor data (temperature, pressure, etc.)
Different timing guarantees with respect to data transfer:
Asynchronous: no restrictions with respect to when data is to be delivered
Synchronous: define a maximum end-to-end delay for individual data packets
Isochronous: define a maximum end-to-end delay and maximum delay variance (jitter is bounded)
A (continuous) data stream is a connection-oriented communication facility that supports isochronous data transmission.
Some common stream characteristics
Streams are unidirectional
There is generally a single source, and one or more sinks
Often, either the sink and/or source is a wrapper around hardware (e.g., camera, CD device, TV monitor)
Simple stream: a single flow of data, e.g., audio or video
Complex stream: multiple data flows, e.g., stereo audio or combination audio/video