Programming Languages: Categories

Programming Languages

Categories

McGraw-Hill Technology Education

Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.

First generation language – Machine languages – Written in binary – Different for every CPU

Second generation languages – Assembly languages – Statements that represent machine code – Code converted by an assembler – Still used to optimize video games

Third generation languages (3GL) – First higher level language – Supports structured and OOP • Code is reusable • Code is portable

– Typically written in an IDE – C/C++ creates games and applications – Java creates web applets – ActiveX creates Web and Windows applets

Fourth generation languages (4GL) – Easier to use than 3GL – Coded in a visual IDE – Tools reduce the amount of code – Object oriented programming – Microsoft .Net is a language – Dream Weaver is an 4GL IDE

Microsoft.NET

Fifth generation language (5GL) – Mystery language – May not be created yet – Will create software automatically

WWW Development Languages • Markup languages – Describe how the text is formatted

• Hyper Text Markup Language (HTML) – Basis of all web pages – Defines web structure using tags – Easy to learn and use – Created with a text editor

WWW Development Languages • Extensible Markup Language (XML) – Stores data in a readable format – Looks like HTML – Allows developers to create tags – Depends on HTML for formatting

XML

WWW Development Languages • Extensible HTML Mobile Profile – XHTML MP – Initially Wireless Markup Language (WML) – Creates pages viewable on a handheld

WWW Development Languages • Cascading Style Sheets (CSS) – Format HTML, XHTML and XSL – Applies consistent formatting to all pages

WWW Development Languages • Web authoring environments – Reduces tedium for creating pages – Tools that simplify web site creation – Macromedia Dream weaver • Simplifies large sites • CSS support is exceptional

– Microsoft FrontPage simplifies large sites – Macromedia Flash creates web animations

WWW Development Languages • Scripting languages – Create dynamic web pages • Change based on user input

– HTML can create static pages – Page is generated as needed

WWW Development Languages • JavaScript – Developed by Netscape – Works inside of HTML – Page verification and simple animation – Based on Java

WWW Development Languages • Active Server Pages (ASP) – Developed by Microsoft – Based on Visual Basic – Good at connecting to Microsoft databases – Runs only on Microsoft servers

WWW Development Languages • Perl – Old UNIX language – Found on all Windows and Linux servers – Excellent web scripting language

WWW Development Languages • Hypertext Pre-Processor (PHP) – Especially good at connecting to MySQL – Very popular language – Runs on UNIX and Windows

Systems Development Life Cycle • SDLC • Organized way to build programs • Consists of five phases

Systems Development Life Cycle • Phase 1: Needs Analysis – Users identify a need – Need is clearly defined using tools

Systems Development Life Cycle • Phase 2: Systems design – Solution to the need is defined – Many tools are used – Prototypes of the solution are built

Systems Development Life Cycle • Phase 3: Development – Solution to the problem is built – Programmers write the solution – Technical writers document the process – Solution is continually tested

Systems Development Life Cycle • Phase 4: Implementation – The solution is installed – Users are converted to the new system – Trainers are important in this phase

Systems Development Life Cycle • Phase 5: Maintenance – IT professionals monitor the product – Bugs are found and fixed – New features are added

Data Communications

McGraw-Hill Technology Education

Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.

Data Communications The movement of computer information from one point to another by means of electrical or optical transmission systems. Such systems are often called data communications networks.

• Telecommunications Includes the transmission of voice and video as well as data.

Fundamental Characteristics of DC

 Delivery  Accuracy  Timeliness  Jitter

Components of DC

Rule 1: Rule 2:

Rule 1:

Protocol

Protocol

Rule 2:

…

…

Rule n:

Rule n:

Message Sender

Medium

Receiver

Data Flow (Transmission)

data flows move in one direction only, (radio or cable television broadcasts)

data flows both ways, but only one direction at a time (e.g., CB radio) (requires control info) data flows in both directions at the same time

Modem Communications • Modems – Modulator/Demodulator • Modulator converts digital to analog

– Speed measured in bits per second (bps) • Current fastest speed is 56 Kbps • Quality of phone lines dictates speed

– V.92 is the current modem standard – Several modem types • • • •

Internal External Voice Fax

Modem Communications • Modem uses – Connection to the Internet – File transfer • Uploading • Downloading

Digital Data Connections • Broadband connection – Any data connection faster than 56 Kbps – Common in business – Becoming popular in home installations

Digital Data Connections • ISDN lines – Integrated Services Digital Network – Basic rate uses three channels • Two data channels each support 64 Kbps • Error correction channel

– Primary rate uses 24 data channels • Support 64Kbps each

Digital Data Connections • T lines – High-capacity voice/data lines – Used to control phone and data – Several variants – T1 transmits at 1.544 Mbps – T3 transmits at 44.736 Mbps

Digital Data Connections • DSL technologies – Digital Subscriber Line – Popular with home users – Speeds range from 100 Kbps to 30 Mbps – Asymmetrical DSL (ADSL) • Upload speed slower than download speed • 1 Mbps for upload and 8 Mbps for download

– Symmetrical DSL (SDSL) • 1.544 Mbps for upload and download

– Requires a DSL modem

Digital Data Connections • Cable modem connections – Popular with home and office users – Requires a cable modem – Maximum speed up to 27 Mbps

Wireless Networks • Benefits – No cable to pull – Mobile devices access network resources – Mobility and flexibility for office workers

Wireless Networks • Wireless 802.11 – Also called Wi-Fi – IEEE standard • Institute of Electronic and Electrical Engineers

– Several versions • 802.11b connects up to 11Mbps • 802.11g connects up to 56Mbps

– Use the same type of devices

Wireless Networks • Wireless Access Point – Center of a wireless network – WAPS combined cover a larger area – Distance to WAP determines bandwidth – Range is 50 to 150 meters – Extension points can extend range

Network Basics

McGraw-Hill Technology Education

Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.

Network Definition • Set of technologies that connects computers • Allows communication and collaboration between users

The Uses of a Network • Simultaneous access to data – Data files are shared • Access can be limited

– Shared files stored on a server – Software can be shared • Site licenses • Network versions • Application servers

The Uses of a Network • Shared peripheral device – Printers and faxes are common shares – Reduces the cost per user – Devices can be connected to the network – Print servers control network printing • Manage the print queue

Sharing Data

File server contains documents used by other computers.

The Uses of a Network • Personal communication – Email • Instantaneous communication

– Conferencing • • • •

Tele conferencing Videoconferencing Audio-conferencing Data-conferencing

– Voice over IP • Phone communication over network wires

Voice Over IP

The Uses of a Network • Easier data backup – Backup copies data to removable media – Server data backed up in one step

Common Network Types • Local Area Network (LAN) – Contains printers, servers and computers – Systems are close to each other – Contained in one office or building – Organizations often have several LANS

Common Network Types • Wide Area Networks (WAN) – Two or more LANs connected – Over a large geographic area – Typically use public or leased lines • Phone lines • Satellite

– The Internet is a WAN

Hybrid Network Types • Campus Area Networks (CAN) – A LAN in one large geographic area – Resources related to the same organization – Each department shares the LAN

Hybrid Network Types • Metropolitan Area Network (MAN) – Large network that connects different organizations – Shares regional resources – A network provider sells time

Hybrid Network Types • Home Area Network (HAN) – Small scale network – Connects computers and entertainment appliances – Found mainly in the home

Hybrid Network Types • Personal Area Network (PAN) – Very small scale network – Range is less than 2 meters – Cell phones, PDAs, MP3 players

How Networks Are Structured • Server based network – Node is any network device – Servers control what the node accesses – Users gain access by logging in – Server is the most important computer

How Networks Are Structured • Client/Server network – Nodes and servers share data roles – Nodes are called clients – Servers are used to control access – Database software • Access to data controlled by server

– Server is the most important computer

How Networks Are Structured • Peer to peer networks (P2PN) – All nodes are equal – Nodes access resources on other nodes – Each node controls its own resources – Most modern OS allow P2PN – Distributing computing is a form

Packets – Pieces of data transmitted over a network • Packets are created by sending node • Data is reassembled by receiving node

– Packet header • Sending and receiving address

– Packet payload • Number and size of data • Actual data

– Packet error control

Network Topologies • Topology – Logical layout of wires and equipment – Choice affects • Network performance • Network size • Network collision detection

– Several different types

Network Topologies • Bus topology – Also called linear bus – One wire connects all nodes – Terminator ends the wires – Advantages • Easy to setup • Small amount of wire

– Disadvantages • Slow • Easy to crash

Bus Topology

Network Topologies • Star topology – All nodes connect to a hub • Packets sent to hub • Hub sends packet to destination

– Advantages • Easy to setup • One cable can not crash network

– Disadvantages • One hub crashing downs entire network • Uses lots of cable

– Most common topology

Star Topology

Network Topologies • Ring topology – Nodes connected in a circle – Tokens used to transmit data • Nodes must wait for token to send

– Advantages • Time to send data is known • No data collisions

– Disadvantages • Slow • Lots of cable

Ring Topology

Network Topologies • Mesh topology – All computers connected together – Internet is a mesh network – Advantage • Data will always be delivered

– Disadvantages • Lots of cable • Hard to setup

Mesh Topology (Web)

Network Media • Links that connect nodes • Choice impacts – Speed – Security – Size

Transmission Media •

two major classes – conducted or guided media  use a conductor such as a wire or a fiber optic cable to move the signal from sender to receiver

– wireless or unguided media  use radio waves of different frequencies and do not need a wire or cable conductor to transmit signals

Guided Transmission Data • Twisted Pair • Coaxial Cable • Fiber Optics

Wire Based Media • Twisted-pair cabling – Most common LAN cable – Called Cat5 or 100BaseT – Four pairs of copper cable twisted – May be shielded from interference – Speeds range from 1 Mbps to 1,000 Mbps

Wire Based Media • Coaxial cable – Similar to cable TV wire – One wire runs through cable – Shielded from interference – Speeds up to 10 Mbps – Nearly obsolete

Coaxial Cable A coaxial cable.

Wire Based Media • Fiber-optic cable – Data is transmitted with light pulses – Glass strand instead of cable – Immune to interference – Very secure – Hard to work with – Speeds up to 100 Gbps

Wireless Media • • • • •

Data transmitted through the air LANs use radio waves WANs use microwave signals Easy to setup Difficult to secure

Network Hardware • Network interface cards – Network adapter – Connects node to the media – Unique Machine Access Code (MAC)

Network Hardware • Network linking devices – Connect nodes in the network – Cable runs from node to device – Crossover cable connects two computers

Network Hardware • Hubs – Center of a star network – All nodes receive transmitted packets – Slow and insecure

Network Hardware • Switches – Replacement for hubs – Only intended node receives transmission – Fast and secure

Network Hardware • Bridge – Connects two or more LANs together – Packets sent to remote LAN cross • Other packets do not cross

– Segments the network on MAC addresses

Network Hardware • Router – Connects two or more LANs together – Packets sent to remote LAN cross – Network is segmented by IP address – Connect internal networks to the Internet – Need configured before installation

Network Hardware • Gateway – Connects two dissimilar networks – Connects coax to twisted pair – Most gateways contained in other devices

Network Cabling • Cabling specifications – Bandwidth measures cable speed • Typically measured in Mbps

– Maximum cable length – Connector describes the type of plug

Network Cabling • Ethernet – Very popular cabling technology – 10 Base T, 10Base2, 10Base5 – Maximum bandwidth 10 Mbps – Maximum distances100 to 500 meters

Network Cabling • Fast Ethernet – Newer version of Ethernet – Bandwidth is 100 Mbps – Uses Cat5 or greater cable • Sometimes called 100Base T

– Requires a switch

Network Cabling • Gigabit Ethernet – High bandwidth version of Ethernet – 1 to 10 Gbps – Cat 5 or fiber optic cable – Video applications

Network Protocols • Language of the network – Rules of communication – Error resolution – Defines collision and collision recovery – Size of packet – Naming rules for computers

Network Protocols • TCP/IP – Transmission Control Protocol/Internet Protocol – Most popular protocol – Machines assigned a name of 4 numbers • IP address • 209.8.166.179 is the White House’s web site

– Dynamic Host Configuration Protocol • Simplifies assignment of IP addresses

– Required for Internet access