Web Development Foundations
(D276) Western Governors
University Latest Update.
, Web Development Foundations
Internet
• Invented in 1969
• Started as four computers
FTP
• File Transfer Protocol
• Early way of transferring files over the internet
• Connect to Servers
• Look at listings of available documents
• Download documents of interest
Web
• World Wide Web
• Created by Tim Berners-Lee. A Swiss researcher who worked at CERN.
• Invented in the early 1990s
• Uses HMTL- Text files that contain links
• Browser- a program that can view HTML files
• HTTP- a set of rules for transferring files among computers.
Separation of duties
• HTML defines the structure and content of a webpage.
• CSS specifies the layout and visible appearance.
• JavaScript describes the dynamic behaviors and actions of a webpage.
1
,IP addresses
• Internet Protocol Address
• IPv4 uses 32-bit addresses
• IPv6 uses 128-bit addresses
• Pv4 and IPv6 currently co-exist and likely will last for a long time.
Domain
• A domain name is a name for an IP address.
• DNS is short for Domain Name System.
• Root Servers - Thirteen main DNS servers exist in the world, and a computer's
operating system or an ISP keeps a reference to the root servers' IP addresses.
o 198.41.0.4 (run by Verisign)
o 192.228.79.201 (run by USC)
o 199.7.91.13 (run by Univ. of Maryland)
o 192.203.230.10 (run by NASA)
• Top-level domains (TLD): .com, .net, .org, .edu, and .gov
• Country code top-level domain (ccTLD): .uk (United Kingdom), .ru (Russia), and
.de (Germany)
• A second-level domain is commonly an organization's name. (Wikipedia)
• Third-level and further level domains refer to sub-computer systems local to
an organization. (www.)
URLs
• Uniform Resource Locator
• The location of a web resource on the web
• A web resource is any retrievable item, like an HTML file, image, video, CSS
stylesheet, etc.
• Scheme - Characters at the beginning of a URL followed by a colon ":" or a colon
and double slashes "://". Common URL schemes include http, https, mailto, and file.
• Hostname - The complete domain name following the scheme in a URL.
• Path - The characters to the right of the hostname in a URL.
• Query string - Optional characters to the right of the question mark (?) in a URL
that provide data for the web server.
• Fragment - Optional characters at the end of a URL that start with a hash character
(#) and refer to a certain location within a webpage.
• URL shortening is a technique to create shorter URLs that redirect to longer URLs.
2
, HTTP
• HyperText Transfer Protocol
• A networking protocol that runs over TCP/IP and governs communication between
web browsers and web servers.
• Transmission Control Protocol/Internet Protocol (TCP/IP) is a protocol suite that
governs how data packets are transferred over the internet from one machine to another.
• HTTP/1.1 is the HTTP standard used for most of the web's lifetime
• HTTP/2, a relatively new HTTP standard that speeds-up the transfer of
information between web browsers and web servers.
• HTTP/3, currently in development, improves the speed of HTTP/2 by using UDP
to transport data packets instead of TCP.
• HTTP request: a message sent from the web browser to the web server. Often the
request asks the web server to send back a web resource like an HTML file, image, CSS
stylesheet, JavaScript file, or video.
• HTTP response: a message sent from the web server back to the web browser in
response to an HTTP request. Often the response contains the requested web resource.
• DNS lookup: sending the domain name to the local DNS and getting back the IP
address of the web server hosting the domain name.
• Request and response headers parts:
1. The start line specifies the HTTP version being used. A request's start line
includes a request type and path; a response's start line includes a status code
and phrase.
2. A header field is a keyword followed by a colon and a value. Header fields
supply additional information about the request or response.
3. A blank line
4. A message body contains data being transferred between a web browser and
web server. In a request, the message body may be empty or contain submitted
form data. In a response, the message body may contain the requested resource.
• Internet Assigned Numbers Authority (IANA) is a standards organization that
manages various internet numbers and symbols, like global IP address allocation, root
zone management in DNS, and media types.
Request Method
• GET- Request a representation of the specified resource.
• HEAD- Request a response identical to GET but without the response body.
• POST- Create a new resource with the contents of the message body.
• PATCH- Modify an existing resource with the contents of the message body.
• PUT- Replace an existing resource with the contents of the message body.
• DELETE- Delete an existing resource.
3
(D276) Western Governors
University Latest Update.
, Web Development Foundations
Internet
• Invented in 1969
• Started as four computers
FTP
• File Transfer Protocol
• Early way of transferring files over the internet
• Connect to Servers
• Look at listings of available documents
• Download documents of interest
Web
• World Wide Web
• Created by Tim Berners-Lee. A Swiss researcher who worked at CERN.
• Invented in the early 1990s
• Uses HMTL- Text files that contain links
• Browser- a program that can view HTML files
• HTTP- a set of rules for transferring files among computers.
Separation of duties
• HTML defines the structure and content of a webpage.
• CSS specifies the layout and visible appearance.
• JavaScript describes the dynamic behaviors and actions of a webpage.
1
,IP addresses
• Internet Protocol Address
• IPv4 uses 32-bit addresses
• IPv6 uses 128-bit addresses
• Pv4 and IPv6 currently co-exist and likely will last for a long time.
Domain
• A domain name is a name for an IP address.
• DNS is short for Domain Name System.
• Root Servers - Thirteen main DNS servers exist in the world, and a computer's
operating system or an ISP keeps a reference to the root servers' IP addresses.
o 198.41.0.4 (run by Verisign)
o 192.228.79.201 (run by USC)
o 199.7.91.13 (run by Univ. of Maryland)
o 192.203.230.10 (run by NASA)
• Top-level domains (TLD): .com, .net, .org, .edu, and .gov
• Country code top-level domain (ccTLD): .uk (United Kingdom), .ru (Russia), and
.de (Germany)
• A second-level domain is commonly an organization's name. (Wikipedia)
• Third-level and further level domains refer to sub-computer systems local to
an organization. (www.)
URLs
• Uniform Resource Locator
• The location of a web resource on the web
• A web resource is any retrievable item, like an HTML file, image, video, CSS
stylesheet, etc.
• Scheme - Characters at the beginning of a URL followed by a colon ":" or a colon
and double slashes "://". Common URL schemes include http, https, mailto, and file.
• Hostname - The complete domain name following the scheme in a URL.
• Path - The characters to the right of the hostname in a URL.
• Query string - Optional characters to the right of the question mark (?) in a URL
that provide data for the web server.
• Fragment - Optional characters at the end of a URL that start with a hash character
(#) and refer to a certain location within a webpage.
• URL shortening is a technique to create shorter URLs that redirect to longer URLs.
2
, HTTP
• HyperText Transfer Protocol
• A networking protocol that runs over TCP/IP and governs communication between
web browsers and web servers.
• Transmission Control Protocol/Internet Protocol (TCP/IP) is a protocol suite that
governs how data packets are transferred over the internet from one machine to another.
• HTTP/1.1 is the HTTP standard used for most of the web's lifetime
• HTTP/2, a relatively new HTTP standard that speeds-up the transfer of
information between web browsers and web servers.
• HTTP/3, currently in development, improves the speed of HTTP/2 by using UDP
to transport data packets instead of TCP.
• HTTP request: a message sent from the web browser to the web server. Often the
request asks the web server to send back a web resource like an HTML file, image, CSS
stylesheet, JavaScript file, or video.
• HTTP response: a message sent from the web server back to the web browser in
response to an HTTP request. Often the response contains the requested web resource.
• DNS lookup: sending the domain name to the local DNS and getting back the IP
address of the web server hosting the domain name.
• Request and response headers parts:
1. The start line specifies the HTTP version being used. A request's start line
includes a request type and path; a response's start line includes a status code
and phrase.
2. A header field is a keyword followed by a colon and a value. Header fields
supply additional information about the request or response.
3. A blank line
4. A message body contains data being transferred between a web browser and
web server. In a request, the message body may be empty or contain submitted
form data. In a response, the message body may contain the requested resource.
• Internet Assigned Numbers Authority (IANA) is a standards organization that
manages various internet numbers and symbols, like global IP address allocation, root
zone management in DNS, and media types.
Request Method
• GET- Request a representation of the specified resource.
• HEAD- Request a response identical to GET but without the response body.
• POST- Create a new resource with the contents of the message body.
• PATCH- Modify an existing resource with the contents of the message body.
• PUT- Replace an existing resource with the contents of the message body.
• DELETE- Delete an existing resource.
3
