Presentation is loading. Please wait.

Presentation is loading. Please wait.

An Introduction to the Internet and the Web Frank McCown COMP 250 – Internet Development Harding University Photos were obtained from the Web, and copyright.

Similar presentations


Presentation on theme: "An Introduction to the Internet and the Web Frank McCown COMP 250 – Internet Development Harding University Photos were obtained from the Web, and copyright."— Presentation transcript:

1 An Introduction to the Internet and the Web Frank McCown COMP 250 – Internet Development Harding University Photos were obtained from the Web, and copyright is held by the respective owners. Short History of Computing by Frank McCown is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported LicenseCreative Commons Attribution-NonCommercial 3.0 Unported License

2

3

4 The Internet is a global system of interconnected computer networks that use the standard Internet Protocol Suite (TCP/IP) to serve billions of users worldwide. networksInternet Protocol Suite Internet Computer 1Computer

5 Internet Protocol Suite Internet Protocol (IP): directs packets to a specific computer using an IP address Transmission Control Protocol (TCP): directs packets to a specific application on a computer using a port number. – Common port numbers: Common port numbers 22 – ssh 23 – telnet 25 – 80 – Web

6

7 Web VoIP IM Streaming video Internet != Web The Internet File transfer

8 Overview of the Web Internet Client – Web BrowserWeb Server World Wide Web: The system of interlinked hypertext documents accessed over the Internet using the HTTP protocol

9 Web Browser Software that runs on the client used to access and display web content

10 Mobile Web Browser Mobile browsers account for 18% of web access in Aug 2013

11 Web Server A computer (or software running on a computer) on the Internet that listens for HTTP requests, typically on port 80, and responds with HTTP responses Apache : 52.2% Microsoft IIS: 19.7% ngnix: 13.6% Google: 3.9% Market Share for Top Servers Across All Domains, Aug 1995 – July 2013

12 Hypertext Transfer Protocol (HTTP) Protocol that runs over TCP/IP and governs communication between web browsers and web servers Client Request GET /comp/ HTTP/1.1 Host: Server Response HTTP/ OK Content-Length: 6018 Content-Type: text/html Content-Location: Last-Modified: Mon, 05 Jul :49:40 GMT Server: Microsoft-IIS/6.0 Harding University - Computer Science Example request for

13 Uniform Resource Locator (URL) A URL identifies the location of a resource on the Web. schemehostnamepath local hostname domain name TLD

14 Domain Name System (DNS) DNSDNS is a hierarchical look-up service that converts a given hostname into its equivalent IP address Etc... DNS Server DNS servers contact parent servers for missing entries Authoritative name servers are responsible for specific domains Warning: DNS cache poisoningDNS cache poisoning

15 Example: Web Page Request Client (Web Browser)Web Server (4) HTTP GET bar.html (1) Enter URL (6) HTTP Response (5) Locate the resource (7) Parse HTML & display (8) HTTP GET image1 (N) HTTP GET imageX Potentially many requests & responses DNS (2) foo.org (3)

16 Dissecting the Request GET /comp/ HTTP/1.1 Host: User-Agent: Mozilla/5.0 Firefox/3.6.8 Request type

17 Dissecting the Request GET /comp/ HTTP/1.1 Host: User-Agent: Mozilla/5.0 Firefox/3.6.8 Relative URL

18 Dissecting the Request GET /comp/ HTTP/1.1 Host: User-Agent: Mozilla/5.0 Firefox/3.6.8 HTTP version

19 Dissecting the Request GET /comp/ HTTP/1.1 Host: User-Agent: Mozilla/5.0 Firefox/3.6.8 Hostname

20 Dissecting the Request GET /comp/ HTTP/1.1 Host: User-Agent: Mozilla/5.0 Firefox/3.6.8 Identify client

21 Dissecting the Response HTTP/ OK Content-Length: 6018 Content-Type: text/html Content-Location: Last-Modified: Mon, 05 Jul :49:40 GMT Server: Microsoft-IIS/6.0 Harding University - Computer Science Etc... Header Message body HTTP version Status code & phrase

22 Status Line HTTP/ OK Popular status codesPopular status codes: 200Successful 301 Moved permanently 302 Found under different temporary URI 304Not modified 403Forbidden 404Not found 500Internal server error HTTP version Status code & phrase

23 Dissecting the Response HTTP/ OK Content-Length: 6018 Content-Type: text/html Content-Location: Last-Modified: Mon, 05 Jul :49:40 GMT Server: Microsoft-IIS/6.0 Harding University - Computer Science Etc... Header Message body Number of bytes in response

24 Dissecting the Response HTTP/ OK Content-Length: 6018 Content-Type: text/html Content-Location: Last-Modified: Mon, 05 Jul :49:40 GMT Server: Microsoft-IIS/6.0 Harding University - Computer Science Etc... Header Message body MIME type

25 Popular MIME types text/html text/plain image/jpeg image/gif image/png application/pdf application/msword application/vnd.ms-excel video/quicktime IANA list of MIME types

26 Dissecting the Response HTTP/ OK Content-Length: 6018 Content-Type: text/html Content-Location: Last-Modified: Mon, 05 Jul :49:40 GMT Server: Microsoft-IIS/6.0 Harding University - Computer Science Etc... Header Message body URI for resource

27 Dissecting the Response HTTP/ OK Content-Length: 6018 Content-Type: text/html Content-Location: Last-Modified: Mon, 05 Jul :49:40 GMT Server: Microsoft-IIS/6.0 Harding University - Computer Science Etc... Header Message body When the file was last modified on the server

28 Dissecting the Response HTTP/ OK Content-Length: 6018 Content-Type: text/html Content-Location: Last-Modified: Mon, 05 Jul :49:40 GMT Server: Microsoft-IIS/6.0 Harding University - Computer Science Etc... Header Message body Web server software

29 Dissecting the Response HTTP/ OK Content-Length: 6018 Content-Type: text/html Content-Location: Last-Modified: Mon, 05 Jul :49:40 GMT Server: Microsoft-IIS/6.0 Harding University - Computer Science Etc... Header Message body HTML displayed in the browser

30 How can I see the HTTP headers? Chrome – Ctrl-Shift-I Developer Tools – Network button Firefox – Ctrl-Shift-K Web Console – Net button should be down Internet Explorer – F12 Developer Tools – Network tab

31

32


Download ppt "An Introduction to the Internet and the Web Frank McCown COMP 250 – Internet Development Harding University Photos were obtained from the Web, and copyright."

Similar presentations


Ads by Google