CSCE 120

A system of interconnected computer networks that use the Internet protocol suite (TCP/IP) to link devices. The internet is a collection of smaller networks that all combined create one large, all-inclusive global network

X

https://www.google.com/imghp?hl=en&tab=ri&ogbl

• https - Protocol (http)
• www.google.com - The Host or Host Name
• google.com - Domain Name
• port - Default port for https is 443 (default port for secure web server)
• imghp - Resource (File) Path (typically refers to a file or location on the web server)
• ?hl=en&tab=ri&ogbl - Query Parameters
  The parameters are generally in (key,value) pair and separated by &. Example: hl is the key and en is the value

https://myred.nebraska.edu/psp/myred/NBL/HRMS/?cmd=login&d=cs

• https - The protocol
• myred.nebraska.edu - The host or hostname
• nebraska.edu - Domain name
• myred - subdomain
• port - 443 which is the default port for secure web servers. If another port is used, it would be specified (i.e 4488)
• /psp/myred/NBL/HRMS/ - The Resource Path on the server
• ?cmd=login&d=cs - Query Parameters also known as Query String. Parameters start with a question mark (?) and are separated with an ampersand (&).

http://video.google.co.uk:80/videoplay?docid=-724&hl=en#00h02m30s

• http - The protocol
• video.google.co.uk - The host or hostname
• video - The subdomain
• google.co.uk - The domain name
• uk - The top-level domain or TLD . Also referred to as a country-code top-level domain or ccTLD. For google.com, the TLD would be com
• co.uk - The second-level domain (SLD)
• 80 - The port which is the default port for web servers. Default ports don't need to be specified. A web server can listen on other ports such as 8080
• /videoplay - The Resource path. Typically refers to a file or location on the web server
• ?docid=-724&hl=en#00h02m30s - The URL Parameters (Query Parameters or Query String)
• #00h02m30s - Fragment or named anchor. The fragments are used to refer to an internal section within a web document.

HTTP is the underlying basis of data communication for the Web. Below are three basic features that make HTTP a simple but powerful protocol.

• HTTP is connectionless The client makes a request, a connection is established. The server processes the request and sends the response back. Then the client disconnects the connection.
• HTTP is media independent Any type of data can be sent as long as both the client and the server know how to handle the content. The content type is identified by using appropriate MIME-Type.
• HTTP is stateless The server and client know of each other only during a current request. Once the current request is completed, they both lose knowledge of each other - They are disconnected.

HTTPS is the secure version of HTTP. With HTTPS the communications between the client (browser) and the server(Web site) are encrypted. The vast majority of today's web ulilizes on HTTPS

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1. User issues a webpage (URL) on a browser
2. Browser send an HTTP request to the server
3. Server maps the URL to the appropriate resource and does necessary processing
4. Server returns the HTTP response
5. Browser formats and displays the content

HTTP defines methods (verbs) to indicate the desired action to be performed on the identified resource. These verbs are GET, HEAD, POST, PUT, DELETE, TRACE, OPTIONS, CONNECT, PATCH. The details and implementation of these verbs are beyond the scope of this class, however it is important to know the two most used verbs.

HTTP Request

    General
    Request URL: https://cse.unl.edu/about
    Request Method: GET
    Status Code: 200 OK
    Remote Address: 129.93.165.2:443
    Referrer Policy: no-referrer-when-downgrade

    Response Header
    Accept-Ranges: bytes
    Access-Control-Allow-Methods: GET
    Access-Control-Allow-Origin: *
    Age: 0
    Cache-Control: public, max-age=86400
    Connection: Keep-Alive
    Content-Encoding: gzip
    Content-Language: en
    Content-Type: text/html; charset=utf-8
    Date: Sun, 16 Jun 2019 22:08:34 GMT
    Etag: "1560722914-1"
    Expires: Sun, 19 Nov 1978 05:00:00 GMT
    Keep-Alive: timeout=15, max=92
    Last-Modified: Sun, 16 Jun 2019 22:08:34 GMT
    Link: ; rel="canonical",; rel="shortlink"
    Server: Apache/2.4.6 (CentOS) PHP/7.0.33
    Transfer-Encoding: chunked
    Vary: Cookie,Accept-Encoding
    Via: 1.1 varnish (Varnish/6.0)
    X-Cacheable: Yes
    X-Content-Type-Options: nosniff
    X-Drupal-Cache: MISS
    X-Generator: Drupal 7 (https://www.drupal.org)
    X-Powered-By: Mono
    X-Varnish: 23408249
    X-XSS-Protection: 0

    Request Header
    Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3
    Accept-Encoding: gzip, deflate, br
    Accept-Language: en-US,en;q=0.9
    Cache-Control: no-cache
    Connection: keep-alive
    Cookie: _ga=GA1.2.1431067304.1543549385; __utma=1.1431067304.1543549385.1556247924.1556247924.1;
    Host: cse.unl.edu
    Pragma: no-cache
    Referer: https://cse.unl.edu/
    Upgrade-Insecure-Requests: 1
    User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/75.0.3770.80 Safari/537.36