Streams

Streams
An Introduction

Prof. David Bernstein
James Madison University

Computer Science Department

bernstdh@jmu.edu

Overview

What Are Streams?

Definition:
- A sequence of data with indeterminate length
- UNIX streams end with Ctrl-D and Windows streams end with Ctrl-Z
Analogies:
- A river
- A "waiting line" of people

One Conceptual Model of a Stream

Another Conceptual Model of a Stream

A Third Conceptual Model of a Stream

UML Diagram:
Interpretation:
- A communications channel connects an output stream to an input stream
Forms of the Connection:
- Network connection, memory buffer between threads, I/O devices

Observations

The Benefits of the Stream Concept

Streams provide a uniform data interface that is independent of the channel
Streams can be used to buffer data, allowing the source and sink to operate at different speeds
Filters can be used to modify streams. Each filter can be simple but they can be used in combination if necessary.

Streams and Streaming Protocols

What Is a Communications Protocol?
- An agreement that governs the procedures used to exchange information between cooperating entities
What is a Streaming Protocol:
- A protocol in which the receiver does not wait for all of the data to be received before starting to process it
Are All Protocols that use Streams "Streaming Protocols"?
- No, a protocol can use a stream for communication and still wait for all of the data before starting to process it