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WAN
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Wide Area Networks (connects states, nations or even continents)
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Ordered Lists
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start tag list item
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Adjusting tables
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colspan (to make a cell span more than a single column)(use with td or th)rowspanwidth/height of cell (use with th or td or tr)
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Hostnames
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An alternate naming scheme supported by application level programs
ex: www.whitehouse.gov
A computer can have multiple hostnames (usually only one)
Converted into IP number by computer
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multi-column w/ header
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header can be made in body before <table>
w/ <h1 align="center"><font size="" face="">...</h1>
or an image can be added, but use the <div> tag to center!!
<div align="center">
<img scr="blah.gif" alt="blah"></div>
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Colors
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16 standard colors for HTML; 16.7 million custom colorscreated w/ hexidecimals
Red, Green, Blue
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Absolute Reference
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Specify the name of the protocol, the name of the webserver and the name of the file which the web browser should retrieve
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Cache Memory
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Small amount of memory that is even faster than main memoryStores information that is frequently accessed
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Multiprocessing
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Used to overcome the processor bottleneck\Break down the problem our computer is working on into separate tasks which can be executed by multiple processors working simultaneously
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Processing
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CPU is bottleneck which limits the overall performance of the computerMain CPU and other processor specifically for graphics
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Software
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Application Software and System Software
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Adding background images
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<body background="images/background.gif">...</body>
browser repeats pattern, vertically...so play w/ gif
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GIF
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256 color maximumeffect of watching a movie by stringing many images together into a single filelossless
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Background for webpage
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The <body> tag has a background attribute that allows to set image as background of body;
if not big enough, repeats!
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Computer language
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formal language that defines how humans communicate with a computer
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LAN
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Local area networks (small)
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Client/Server
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Model of computing
Two different types of computers participate: client computers and server computers
Client comps: multi-purpose
Server comps: dedicated single-purpose; sends webpages to client comps upon request
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Relative Reference
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Used to create links between files which are located on the same webserverIt assumes that the webpage referred to is found at the same location as the current webpage
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Main Computer Memory
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RAM stores information on computer chips using a series of electronic switches.Switches are either turned on or offInformation in main memory is lost when the computer is turned off.Main computer memory is relatively expensive.
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List Types
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UnorderedDefinitionNumbered
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Application Software
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Programs used for productivity or entertainment purposes
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Program Execution
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CPU can only execute instructions that are in main memoryInstructions copied onto main computer memory from hard diskSaving--copies current data specific to task onto hard disk
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Link Destinations
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Image Formats
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JPEG- PhotographsGIF- Non-photographic imagesPNG- Non-photographic images (more advanced)
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WAN
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Wide Area Networks (connects states, nations or even continents)
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T1, T3, OC3, OC12
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Other types of connections
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Headers
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Consists of a header type followed by a colon ':' followed by a corresponding value
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Absolute vs. Relative References
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Relative references make a website more portable
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Virtual Memory
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Extends the amount of apparent main memory by using a section of the hard disk which acts as if it were additional main memoryCPU can only access information in main memoryAllows us to run more programs at once than we would normally be able to
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Creating a relative reference to a file in another folder
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Example:.../index.html
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Address
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Reference number for each individual byte
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ROM
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Read Only MemoryInformation cannot be changedSwitches have been glued either on or offNegligible compared to RAMModern ROM can be changed (Flash ROM)Contents are still kept when the computer is turned off
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Hardware- Processing
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Central Processing Unit; responsible for carrying out the instructions contained in a computer program
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Blank Space (vertical)
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empty <td> w/ specified heighth
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Internet Protocol Layers
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Application layerTransport layerNetwork layerPhysical/Data layer
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Debugging
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Getting rid of bugs/errors so source code can validate and work properly
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Tags
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HTML tags tell the computer how to display a webpage.
They often work in pairs
Start tag <>
End tag </>
Start & end tags create a container for text
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Ethernet
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Slightly oversized telephone cable100 megabits per second
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HTML Table & Separating into Multiple Columns
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Columns created with <table> and single <tr> row and one <td> table data for each column
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PNG
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alternative to GIFallows for semi-transparent images24-bit color (16.7 million colors)lossless
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Definition Lists
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definition list definition term
definition description
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Attributes
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Can be added to tags to provide additional information
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Semantic Language
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Vocabulary of HTML
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Navigation sidebar (multi-page)
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-home should be saved as index.html, can be copied
-must organize files first on comp (location scheme)
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Image size
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height and width attributespixelspercentages
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Bandwidth
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The range of frequencies in the electromagnetic spectrum that a medium can use to send informationBroadband or Narrowband
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Network topology
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The form in which the computers on a network are connected together
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MAC addresses
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Used at physical/data layerAllocated on the basis of which company manufactured a particular cardDo not provide any information as to where the computer is locatedRouting of messages within an individual LAN
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Navigation & Advertising Sidebars
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Created with table columns! ie <td> within a <tr>
Navigation usually on left.
Advertising on right.
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MAN
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Metropolitan Area Networks (within a city or small region)
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Packet Switching vs. Circuit Switching
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Telephones are circuit switching based (quality of connection remains constant)Internet is packet switching based (all circuits shared)
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In-Line Tags/Text Level Tags
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tell text what to do
bold <b>
italics <i>
underline <u>
inc font by 1 <big>
dec font by 1 <small>
changes size, color of text or font face <font>
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TCP
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Transmission Control Protocol
Provides application built on top of it with a direct connection between any two computers on the Internet
Implementation of the TCP protocol takes data sent by an application and breaks it into chunks small enough to fit into individual IP packets
The TCP implementation sends the packets through the Internet
TCP numbers the packets and reorders them if necessary when they are received
Automatically resends a copy of a packet if it is lost
Associated with specific applications
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URL
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Uniform resource locators
used to identify specific files, web pages, and other information at a much more detailed level than that provided by hostnames and IP numbers
Begins with an identifier determining what kind of information is being referenced
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Hypertext
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Text in one part of a document may be connected to text in other parts of the document via links
Replacement for books
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Inserting comments
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JavaScript
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Computer programing language associated with HTML
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Network Layer
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Responsible for transferring data across the InternetNo error checkingData limited to small size "packets"
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Cable Modem
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Uses the cable used to bring television1.5 megabits per second or faster
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Peer-to-Peer
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Two or more computers cooperate to carry out a task
Neither computer is in charge
Ex: Chat application
Requires fewer resources
Reduces legal liability for file sharing programs
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Alignment of an image
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align="value"values include:topbottommiddleleftright
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IP numbers/addresses
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Every computer on the Internet has its ownAssigned when a computer is first connected to the InternetFour numbers between 0 and 255 separated by dotsUsed by network layer (help route messages on the Internet)
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Ring network
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The computers are linked into a ringWhen a computer wants to send a message, it sends it to its neighbor on the right (counterclockwise)If one of the computers fails, messages won't be able to make it around the ring to their destination
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IP
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Does not identify which application running on the original computer sent the message or which application on the recipient computer should receive the packet
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JPEG
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24 bit color (like PNG)lossy
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Incremental development
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Used for complex projects; built in steps/stages & checked before going on
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The Request Line
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GET-most common request, requests that a webserver send a file
HEAD-requests information on a file
POST-requests the information that a user has entered into the webpage form, webserver sends back the results
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Markup
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We take unformatted text and mark ip up for display on a computer; HTML is a markup language-- markup is done in a standard text editor
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File Extensions
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.xls (excel)
.doc (word document)
.txt (text)
.html (what html must be saved as to open!)
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Sidebar summary
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-single row tables w/ multiple columns a <td> for main and a <td> for sidebar!
-remember valighn="top"
-fix width attribute within <td> tab
-placement within a sidebar can be controlled w/ inner <table> contained in sidebar <td>
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HTTP
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Hypertext Transfer Protocol
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SMTP
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Simple Mail Transfer Protocol
Used to send mail from one computer to another
E-mail is usually sent to a mail server computer
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Changing font notes
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<font> tags are limited to in-line text;block elements illegal
so:
<p><font face"sans-serif" size="4"></font></p>
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System Software
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Used to manage the computerOperating systemWindows and MacOSGraphical interface for the user allowing her/him to start and stop programs and manage files
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File level tags/HTML tags
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These are necessary for all HTML pages!
start of XHTML <?xml>
<html> all contents of html
<head> used by browser, not displayed
<title> listed IN head, displayed in web title bar (can't contain formatting)
<body> actual content-- including background/text color
must close each of these!
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Binary Number System
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Each switch represents a single binary digit (BIT)Byte= Eight bitsWords= Organized set of bytesAddress= Reference number for each individual byte
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Bridge
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Connects together the same type of network technology
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HTML
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Hypertxt Markup Language
computer language used to define layout and formatting information on webpages;
not a program
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Router
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Special-purpose device that connects different types of technology
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Application Layer
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Defines actual control and data transfer needed for specific applicationsWide range of different protocols for e-mail, web, IM
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Serial and Parallel Connections
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Serial--connection bits are sent through the connection one at a timeParallel--multiple bits are passed through simultaneously over different wires in the connector(Newer connections--single bits are faster speeds)
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Syntax Rules
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like grammar rules used in HTML, determine if sentance/construct is legal
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Input/Output
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Devices used to get information from the user or to present infomration to the user.Monitor, keyboard, mouse...Exgternal devices (peripherals--printers and scanners)
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Element
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The "container" includes
start tag, end tag, and contents
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Divisions
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used to create sections within an HTML document
attributes:
align (center, right, left)
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Hardware- Storage
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Most information is stored in one of two places--the main computer memory or the computer hard disk.
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WYS/WYG
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Word, unlike a standard text editor, displays text as it is seen. There is no need for markup, all formatting is done within the file
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Computer Hard Disk
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Information stored on the computer hard disk is stored magnetically.Retained even when the power is turned off.Cheaper per byte.
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Digital Subscriber Line
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DSLTakes the unused bandwidth from copper telephone wires and uses it to transmit digital informationSpeed varies according to subscriber's distance from the telephone company's central office
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Images
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All image tags require an alt attribute
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Vertical Placement of buttons & ads
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Each button/ad has its own <tr> with a single <td>
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Thrashing
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Programs run slowly and the hard disk churns due to excessive switching between programs and lack of real main memory
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Linking
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anchor tag
end tag
href (hypertext reference)
Example:
URL
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Bridge
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Connects together the same type of network technology
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Ads as images in ad column
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can hae multiple rows w/ images in <td>
remember to set border="0" on ad's <img> tag
provide height and width for better display
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Connection mediums
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Twisted pair cables (similar to phone line)Coaxial cables (similar to cable television line)Fiber optic cables
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Star network
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Every computer is connected to a central hub computerAny computer except the central hub can fail without affecting others
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Telephone/Modem (POTS)
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Connects a computer to another computer using the standard telephone serviceUses a modem (converts from bits and bytes to an analog tone that can be transmitted over a telephone line)56 kilobits per second maximum
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Protocols vs. Programs
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Protocol is a specificationDefines how programs written to support the protocol should actMore than one program can support the same protocol
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Example navigation tab html code
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<tr><td><a href=index.html">
<img src="buttons/home-button.gif" alt="home" border="0" width="x" height="x" /></a></td></tr>
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Block Level Tags
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control larger amounts of text
paragraph <p>
line break in text <br />
headers <h1>...<h6>
horizontal line <hr />
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Peripherals
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USB (Universal Serial Bus)USB 2.0IEEE-1394 (Firewire)BluetoothWi-Fi
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Physical/Data Layer
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Defines physical connections between computers in networkDetermines how 0s and 1s are sent on medium (eg voltage levels)
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Blank Space (horizontal)
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empty <td> with specified width
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RAM
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Random Access MemoryComputer can change contents of RAM at any point
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Nesting Rules
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Part of syntax rules-- sets of formatting tags can be used together, but must be properly nested
<b>an example of <i>nesting</i><b>
(must be closed in order!!!)
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Linking to Mail
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Bus network
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Computers are connected directly to a central called a busContention issues--multiple computers may try to send messages out on the bus at the exact same time
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Transport Layer
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Builds on Network LayerSupports error detection and correctionProvides transport of unlimited amounts of data
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The Status Line
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example: HTTP/1.1 200 OK
ERRORS are displayed here
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