ce data - Data Structures Methods of organizing data A...

Info iconThis preview shows pages 1–19. Sign up to view the full content.

View Full Document Right Arrow Icon
Data Structures • Methods of organizing data – A structure like any other in engineering – Requires design • What is the data for? • What operations will be needed? • What are the properties of the data being stored? – Provide means for finding particular data items – Allow information to be restored.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Data Structures • Examples – Hardware implementations • Page buffer in the printer • frame buffer in a graphics system – Software • A packet switched communications system • The process structures in an operating system
Background image of page 2
Example - A Packet Switched System • Data is transmitted in blocks (packets) • Each packet can be sent by a different route to the destination • Each packet can arrive at a different time • Requirement: – Design a data structure which will enable the original message to be put together correctly
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Example - A Packet Switched System Hello World, please respond.
Background image of page 4
Example - A Packet Switched System World, please respond. Hello
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Example - A Packet Switched System Hello please respond. World,
Background image of page 6
Example - A Packet Switched System respond. World, Hello please
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Example - A Packet Switched System respond. World, Hello please
Background image of page 8
Example - A Packet Switched System respond. Hello please World,
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Example - A Packet Switched System respond. Hello please World,
Background image of page 10
Example - A Packet Switched System • Each packet is a text string • Each packet has a position in the message ADDRESS TEXT • An arriving packet goes into a pool • The pool is sorted
Background image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Example - A Packet Switched System
Background image of page 12
Example - A Packet Switched System • What if several messages are sent to the same destination simultaneously?
Background image of page 13

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Example - A Packet Switched System • What if several messages are sent to the same destination simultaneously? – Add a second tag to indicate the message number. • These properties define the abstract data type pool. Character strings of length one packet ending in a null Message number Packet number
Background image of page 14
An Abstract Data Type • Describes the form of the data – Component element types (e.g. characters) – A structure that relates the component element values (e.g. a linear arrangement) – A domain of allowable structures (e.g. from 0 to 80 characters in a packet) • Defines how components may be accessed – A set of operations on the values in the domain
Background image of page 15

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
An Abstract Data Type • The abstract data type pool structures data into – a key (the position in the message) – data (the packet itself) • This structuring is necessary - a key always exists but may be implicit or, sometimes, the data may itself be the key.
Background image of page 16
A Data Structure • The physical implementation of the data type. • Maps the abstract data type onto the available environment.
Background image of page 17

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
“Pool” • Store (X) – Store a packet number and the associated text of packet X in the pool. • Retrieve (m,n,T)
Background image of page 18
Image of page 19
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 179

ce data - Data Structures Methods of organizing data A...

This preview shows document pages 1 - 19. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online