CS 80 chap one slide notes Flashcards
cards from professor slides show from book
The Internet
global network of computers—was made possible by the convergence of computing and communications technologies
primary goal of APRANET ?
HINT: AT THE SAME TIME
One of the primary goals for ARPANET was to allow multiple users to send and receive information simultaneously over the same communications paths (e.g., phone lines).
DESCRIBE PACKET SWITCHING
NetworkS operated with a technique in which digital data was sent in small bundles called packets.
WHAT DOES PACKET SWITCHING ADRESS ATTRIBUTES DO?
The address information allowS packets to be routed to their destinations
WHAT HAPPENS TO INFORMATION THAT ARRIVES OUT OF ORDER IN PACKET SWITCHING
The sequencing information helped in reassembling the packets—
—into their original order for presentation to the recipient.
which, because of complex routing mechanisms, could actually arrive out of order
BECAUSE PACKET SWITCHING INTERMIXES DATA AND SENDS THROUGH THE NETWORK -IF A PORTION OF THE NETWORK FAILS WHAT HAPPENS
If a portion of the network failed, the remaining working portions would still route packets from senders to receivers over alternative paths for reliability.
The network was designed to operate without centralized control.
WHY WAS IP DEVOLOPEDN AND USED?
HINT: A MAIL MEN IS A COMINCATION CONDUIT.: IF INTERNET IS A MAIL MEN AND THE MAIL IS A NETWORK THEN THE ADRESS IS THE IP
TO GET different networks to communicate.
for both intraorganization (i.e., within the organization) and interorganization (i.e., between organizations) communications.
Each computer on the Internet has a unique _________
Each computer on the Internet has a unique IP address.
The current IP standard, Internet Protocol version 4 (IPv4), has been in use since 1984 and will soon run out of possible addresse
Describe IPv6
IPv6 features enhanced security and a new addressing scheme expanding the number of IP addresses available so that we will not run out of IP addresses in the forseeable futur
what was the internet initially used for
nitially, Internet use was limited to universities and research institutions; then the military began using it intensively
WHATS BAND-WITH
Bandwidth (i.e., the information-carrying capacity)
Explain HOW THE WEB INTERACRTS WITH COMPUTERS AND INFORMATION
The World Wide Web allows computer users to execute web-based applications and to locate and view multimedia-based documents on almost any subject over the Internet.
WHO AT CERN ((EU organization FOR nuclear research) CREATED HTML AND WHAT YEAR.?
In 1989, Tim Berners-Lee of CERN (the European Organization for Nuclear Research) began to develop a technology for sharing information via hyperlinked text documents. Berners-Lee called his invention the HyperText Markup Language (HTML).
WHAT IS HTTP EXPLAIN
he wrote the Hypertext Transfer Protocol (HTTP)—a communications protocol used to send information over the web.
TIM BERNES also wrote communication protocols to form the backbone of his new information system, which he called the World Wide Web. In particular,
WHAT DOES A URL specify?
specifies the address (i.e., location) of the web page displayed in the browser window.
IN HTML CODE. WHAT DOES URL’S BEGIN WITH?
URLs usually begin with http://
HTTPS STAND FOR AND EXPLAIN IT?
HTTPS is the standard for transferring encrypted data on the web.
WHAT DOES THE SYNTAX OF HTTPS
https://
Hypertext Transfer Protocol Secure (HTTPS).
URLs of websites that handle private information, such as credit card numbers, often begin with
DESCRIBE TLS (TRANSPORT CONTROL LAYER)
****cryptographic
(TLS) cryptographic schemes IS USED for securing communications and identification information over the web.
It combines HTTP with the Secure Sockets Layer (SSL) and the more recent Transport Layer Security
Explain Web 1.0
IN 1998 Marc Andreessen, developed Mosaic, AND Netscape, WITCH igniting the explosive Internet economy of the late 1990s.
whose team at the National Center for Supercomputing Applications (NCSA)
WHAT IS HYER text mark UP language?
In its simplest form, a web page is nothing more than an HTML document that describes to a web browser the document’s content and structure
(with the extension .html or .htm)
DESCRIBE HYPERLINKS
which, when clicked, load a specified web document. Both images and text may be hyperlinked.
WHAT TYPES OF FILES AND OR ACTIONS DOES HYPERLINKS RETRIVE
Hyperlinks can reference other web pages, e-mail addresses, files and more.
IF a hyperlink’s URL is in the form mailto:emailAddress, clicking the link loads your default e-mail program and opens a message
If a hyperlink references a file that the browser is incapable of displaying HOW DOES IT handle THE REQUEST?
If a hyperlink references a file that the browser is incapable of displaying, the browser prepares to download the file,
and generally prompts the user for information about how the file should be stored.
NAME A COUPLE WEB SERVERS
Popular web servers include Apache’s HTTP Server and Microsoft’s Internet Information Services (IIS).
Let’s examine the components of the URL HTTP://WWW.DITEL.COM/BOOKS/DOWNLOADS.HTML
http://
www.deitel.com/books
/downloads.html
The text http:// indicates that the HyperText Transfer Protocol (HTTP) should be used to obtain the resource.
hostname www.deitel.com —the name of the web-server computer on which the resource resides.
(/books/downloads.html) specifies the resource’s location (/books) and name (downloads.html) on the web server.
EXPLAIN A HOST COMPUTER
This computer is referred to as the host, because it houses and maintains resources.
The hostname www.deitel.com is translated into an _______________? FOR THE BROWSER TO LOACTE WHAT?
—a numerical value that uniquely identifies the server on the Internet.
IP ADRESS
WHAT IS DNS AND WHAT IS ITS FUMCTION?
An Internet Domain Name System (DNS)
The hostname www.deitel.com is translated into an IP (Internet Protocol) address—a numerical value that uniquely identifies the server on the Internet.
IP ADRESS
WHAT DOES GET MEAN IN HTML5
TO obtain a resource from the server. OR REQUEST
EXPLAIN THIS REQUEST FROM USER BOLD PARTS
GET /books/downloads.html HTTP/1.1
GET is an HTTP method indicating that the client wishes to obtain a resource from the server.
HTML The path name of the resource (e.g., an HTML5 document)
(HTTP/1.1). the protocol’s name and version number
WHAT IS A HTTP HEADER
provide additional information about the data that will be sent
IN THE LINE CODE OF THE HTTP WHAT WOULD A HEADER SYNTAX INDICATE TO THE SERVER SENDING AN HTML5 DOC?
CONTENT TYPE:
Content-type: text/html
WHATS DOES MIME STAND FOR? WHAT IS A MIME TYPE AND WHAT DOES IT distinguish?
Multipurpose Internet Mail Extensions (MIME) type of the content that the server is transmitting to the browser.
The MIME standard specifies data formats, which programs can use to interpret data correctly.
GIVES EXAMPLES OF MIME TYPES
For example, the MIME type text/plain indicates that the sent information is text that can be displayed directly.
Similarly, the MIME type image/jpeg indicates that the content is a JPEG image. When the browser receives this MIME type, it attempts to display the image.
The header or set of headers is followed by a __________, which indicates to the client browser that the server is finished sending HTTP headers.
BLANK LINE
The two most common HTTP request types?
GET OR POST
(also known as request methods)
WHAT DOES A GET REQUEST DO?
A get request typically gets (or retrieves) information from a server,
such as an HTML document, an image or search results based on a user-submitted search term.
EXPLAIN A POST REQUEST
A post request typically posts (or sends) data to a server.
Common uses of post requests are to send form data or documents to a server.
A get request appends data to the URL, e.g., www.google.com/search?q=deitel&dietelmusic
describe each process:
www.google.com/ google would be the HOST
/search ____________
?___________
q ________
deiatal_______
= ___________
&————
.
search In this case search is the name of Google’s server-side form
? iseparates the query string from the rest of the URL in a request.handler,
q is the name of a variable in Google’s search form and deitel is the search term.
(=). A name/value pair is passed to the server with the name and the value separated by an equals sign
&If more than one name/value pair is submitted, each pair is separated by an ampersand (&). EXSAMPLE =deitel&dietelmusic
- The server uses data passed in a query string to retrieve an appropriate resource from the server. The server then sends a response to the client. www.google.com/search?q=deitel&ditelmusic*
- A get request may be initiated by submitting an HTML form whose method attribute is set to “get”, or by typing the URL (possibly containing a query string) directly into the browser’s address bar.*
QUERY STRING in the broswer tab is part of the URL WITCH ASSIGNS VALUES TO _______________
assigns values to specified parameters.
A query string commonly includes fields added to a base URL by a Web browser or other client application,
for example as part of an HTML form. A web server can handle a Hypertext Transfer Protocol request either by reading a file from its file system based on the URL path or by handling the request using logic that is specific to the type of resource.
does A post request send forms of data as part of the HTTP message, or the URL?
A post request sends form data as part of the HTTP message, not as part of the URL.
If a form submits several hidden input values along with user-submitted data, the post method might generate a URL that would like?
www.searchengine.com/search
NAME A REASON WHY POST REQUEST WOULD NOT BE SECURE SOLUTION FOR SENDING SENSTIVE INFO.
EVEN THOUGH THE DATA IS NOT PART OF THE RUL AND THE USER CANNOT SEE THE DATA TOOLS ARE available TO EXPOSE THE DATA
WHY DO developers LIKE USING modular OBJECT oriented
—object-oriented programs are often easier to understand, correct and modify.
Software developers are discovering that using a modular, object-oriented design and implementation approach can make software-development groups much more productive than was possible with earlier techniques
A METHOD HOUSES PROGRAM STATMENTS ?
WHAT DO THE STATMENTS DO?
perform its tasks.
It hides these statements from its user, just as a car’s accelerator pedal hides from the driver the mechanisms of making the car go faster.
In object-oriented programming languages, we create a program unit called a class to house the set of methods that perform the class’s tasks.
Performing a task in a program requires a method.
EXPLAIN MESSAGES AND HOW THEY ENS UP AS Method Calls?
NOTE: METHODS ARE HOUSED IN OBJECTS?
THE PROGRAM SENDS messageS TO BE implemented as a method call that tells a method of the object to perform its task.
- For example, a program might call a particular bank-account object’s deposit method to increase the account’s balance.*
- Messages and Method Calls When you drive a car, pressing its gas pedal sends a message to the car to perform a task—that is, to go faster. Similarly, you send messages to an object.*
AN OBJECT IN PROGRAMING HAS ATTRIBUTES THAT IT CARRIES ALONG AS ITS USED IN A PROGRAM describe what attributes a car would have
capabilities to accomplish tasks,
attributes like : color, its number of doors, the amount of gas in its tank,
actionable: current speed and its record of total miles driven (i.e., its odometer reading).
Like its capabilities, the car’s attributes are represented as part of its design in its engineering diagrams (which, for example, include an odometer and a fuel gauge). As you drive an actual car, these attributes are carried along with the car. Every car maintains its own attributes. For example, each car knows how much gas is in its own gas tank, but not how much is in the tanks of other cars.
HOW ARE THESE ATTRIBUTES REALTED TO A ____________
a bank-account object has a balance attribute that represents the amount of money in the account. Each bank-account object knows the balance in the account it represents, but not the balances of the other accounts in the bank.
object’s class.
Classes encapsulate (i.e., wrap) ______ and _____into objects
Classes encapsulate (i.e., wrap) attributes and methods into objects—an object’s attributes and methods are intimately related
Classes encapsulate (i.e., wrap) ______ and _____into objects
Classes encapsulate (i.e., wrap) attributes and methods into objects—an object’s attributes and methods are intimately related
MAKES IT SECURE AND A CLEAN AND CLEAR FREE WAY TO PRODUCE CODE
hiding ATTRIBUTES is crucial to good software engineering.
Inheritance
ABSORBS characterTICS OR TRAITS OF AN EXSITING CLASS CRETING UNIQUE CHARACTERISTICS
A new class of objects can be created quickly and conveniently by inheritance—the new class absorbs the characteristics of an existing class, possibly customizing them and adding unique characteristics of its own
WHY ARE PACKETS FROM different SENDERS OR SOURCES INTERMIXED ON THE SAME DATA LINES??
Packets from different senders were intermixed on the same lines to efficiently use the available bandwidth.
name some action that happen when user initiates hyperlink. what analternate to hyperlinking a source/content?
a web server locates the requested web page and sends it to the user’s web browser. Similarly, the user can type the address of a web page into the browser’s address field and press Enter to view the specified page.
what does DNS do?
database of hostnames and their corresponding IP addresses
and performs the translations automatically.
A query string commonly includes fields added to a base URL by a Web browser or other client application, give an exsample?
reading a file from its file system based on the URL path
or
by handling the request using logic that is specific to the type of resource.
A get request typically limits the query string (i.e., everything to the right of the ?) to a specific number of characters, MARKING LARGE QUERY STRINGS CONVOLUTED
SO WHAT THE ALTERNATIVE
**t’s often necessary to send large amounts of information
The post method is preferred because it hides the submitted data from the user by embedding it in an HTTP message.
WHAT DOES A METHOD HIDE
HINT: Something that is said or written
It hides statements from its user,
just as a car’s accelerator pedal hides from the driver the mechanisms of making the car go faster.
WHAT DOES A METHOD CALL EXECUTE?
HINT : INSTRUCTS
INSTRUCTS METHOD ON HOW TO ACESS AND execute TASK
—an object’s ATTIBUTES and methods ARE_________
intimately related
INTERTWINED
WHAT DO STATMENTS MEAN PERFORM IN TERMS OF OBLECT CLASS PROGRAMING??
A statement is a complete line of code that performs some action
WHAT IS AN EXPRESSION
expression is any section of the code that evaluates to a value
what is a task?
HINT: TPIM
A task is a set of program instructions that are loaded in memory,
then the address registers is loaded with the initial address to start running the task
WHAT DOES FTP STAND FOR? DESCRIBE WHAT IT DOES?
FILE TRANSFER PROTOCOL
ALLOWS FILES TO BE EXCHANGED WITH MULITOLE COMPUTERS
WHAT ARE WEB BASED APPLICATIONS THAT DIVIDE FUNCTINALALITY INTO SEPRATES COMPUTER TIERS?
Web-based applications are often multitier applications
(sometimes referred to as n-tier applications) that divide functionality into separate tiers (i.e., logical groupings of f unctionality).
COLLECTIVE intelligence DESCRIBE?
s shared or group intelligence that emerges from the collaboration, collective effoRTS
CLEINT SIDE SCRIPTING
Client-side scripting with JavaScript can be used to validate user input, to interact with the browser, to enhance web pages, and to add client/server communication between a browser and a web server.
WHAT DO WEB SERVERS DO?
LOCATES REQUESTED WEB PAGE AND SENDS IT TO USERS BROWSER
The em is simply the font size. In an element with a 2in font, 1em thus means 2in. Expressing sizes, such as margins and paddings, in em means they are related to the font size, and if the user has a big font (e.g., on a big screen) or a small font (e.g., on a handheld device), the sizes will be in proportio
