Nuts and Bolts: URL's

INFO 153B/253B: Backend Web Architecture

Kay Ashaolu

URI

• Uniform Resource Identifier
• http://www.yelp.com/biz/jupiter-berkeley#query:jupiters

URI - URL - URN

• URI (Identifier)
  • Identifies some resource (e.g. person or file)
• URL (Location)
  • Specifies the Location of an identifier
  • Implies availability
• URN (Name)
  • Specifies the Name of an identifier
  • Does not imply availability

Example

• Full URI
  • http://www.yelp.com/biz/jupiter-berkeley#query:jupiters
• URL Portion
  • http://www.yelp.com/biz/jupiter-berkeley
• URN Portion
  • www.yelp.com/biz/jupiter-berkeley#query:jupiters

Resource

• Any concept you can name or identify
• So far, typically files
• Also generated pages, like a user profile

Components

• http://www.yelp.com/biz/jupiter-berkeley#query:jupiters

Scheme

• http://www.yelp.com/biz/jupiter-berkeley#query:jupiters
• Specifies how the rest of the URI is laid out
• Typically protocols

Hirearchical

• http://www.yelp.com/biz/jupiter-berkeley#query:jupiters
• "Directions" to the resource through hosts and folders

Domain / Hostname

• http://www.yelp.com/biz/jupiter-berkeley#query:jupiters
• "Site" or machine name

Path

• http://www.yelp.com/biz/jupiter-berkeley#query:jupiters
• Similar to directories, but not necessarily linked!
• Groups common resources together

Path

• Relative
  • biz/jupiter-berkeley#query:jupiters
• Absolute
  • http://www.yelp.com/biz/jupiter-berkeley#query:jupiters

Query (Optional)

• https://www.google.com?q=ischool&ref=class
• Starts with ?
• key=value pairs, delimited by &
• URLEncoded

Port Number

• https://www.ischool.berkeley.edu:443/index.php
• Specifies a port number to connect to
• Ports are like doorways to a server
• Common ports: 80 for HTTP, 443 for HTTPS

Fragment

• http://en.wikipedia.org/wiki/URI_scheme#Examples
• Specify a sub-resource, eg. a section on a page
• Browser will jump to element id

Questions?