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The Application Layer

The Application Layer. Chapter 7. Electronic Mail. Architecture and Services The User Agent Message Formats Message Transfer Final Delivery. Electronic Mail (2). Some smileys. They will not be on the final exam :-). Architecture and Services. Basic functions Composition Transfer

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The Application Layer

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  1. The Application Layer Chapter 7

  2. Electronic Mail • Architecture and Services • The User Agent • Message Formats • Message Transfer • Final Delivery

  3. Electronic Mail (2) Some smileys. They will not be on the final exam :-).

  4. Architecture and Services Basic functions • Composition • Transfer • Reporting • Displaying • Disposition

  5. The User Agent Envelopes and messages. (a) Paper mail. (b) Electronic mail.

  6. Reading E-mail An example display of the contents of a mailbox.

  7. Message Formats – RFC 822 RFC 822 header fields related to message transport.

  8. Message Formats – RFC 822 (2) Some fields used in the RFC 822 message header.

  9. MIME – Multipurpose Internet Mail Extensions Problems with international languages: • Languages with accents (French, German). • Languages in non-Latin alphabets (Hebrew, Russian). • Languages without alphabets (Chinese, Japanese). • Messages not containing text at all (audio or images).

  10. MIME (2) RFC 822 headers added by MIME.

  11. MIME (3) The MIME types and subtypes defined in RFC 2045.

  12. MIME (4) A multipart message containing enriched and audio alternatives.

  13. Message Transfer Transferring a message from elinore@abc.com to carolyn@xyz.com.

  14. Final Delivery (a) Sending and reading mail when the receiver has a permanent Internet connection and the user agent runs on the same machine as the message transfer agent. (b) Reading e-mail when the receiver has a dial-up connection to an ISP.

  15. POP3 Using POP3 to fetch three messages.

  16. IMAP A comparison of POP3 and IMAP.

  17. The World Wide Web • Architectural Overview • Static Web Documents • Dynamic Web Documents • HTTP – The HyperText Transfer Protocol • Performance Enhancements • The Wireless Web

  18. Architectural Overview (a) A Web page (b) The page reached by clicking on Department of Animal Psychology.

  19. Architectural Overview (2) The parts of the Web model.

  20. The Client Side (a) A browser plug-in. (b) A helper application.

  21. The Server Side A multithreaded Web server with a front end and processing modules.

  22. The Server Side (2) A server farm.

  23. The Server Side (3) (a) Normal request-reply message sequence. (b) Sequence when TCP handoff is used.

  24. URLs – Uniform Resource Locaters Some common URLs.

  25. Statelessness and Cookies Some examples of cookies.

  26. HTML – HyperText Markup Language (b) (a) The HTML for a sample Web page. (b) The formatted page.

  27. HTML (2) A selection of common HTML tags. some can have additional parameters.

  28. Forms (a) An HTML table. (b) A possible rendition of this table.

  29. Forms (2) (a) The HTML for an order form. (b) The formatted page. (b)

  30. Forms (3) A possible response from the browser to the server with information filled in by the user.

  31. XML and XSL A simple Web page in XML.

  32. XML and XSL (2) A style sheet in XSL.

  33. Dynamic Web Documents Steps in processing the information from an HTML form.

  34. Dynamic Web Documents (2) A sample HTML page with embedded PHP.

  35. Dynamic Web Documents (3) (a) A Web page containing a form. (b) A PHP script for handling the output of the form. (c) Output from the PHP script when the inputs are "Barbara" and 24 respectively.

  36. Client-Side Dynamic Web Page Generation Use of JavaScript for processing a form.

  37. Client-Side Dynamic Web Page Generation (2) (a) Server-side scripting with PHP. (b) Client-side scripting with JavaScript.

  38. Client-Side Dynamic Web Page Generation (3) A JavaScript program for computing and printing factorials.

  39. Client-Side Dynamic Web Page Generation (4) An interactive Web page that responds to mouse movement.

  40. Client-Side Dynamic Web Page Generation (5) The various ways to generate and display content.

  41. HTTP Methods The built-in HTTP request methods.

  42. HTTP Methods (2) The status code response groups.

  43. HTTP Message Headers Some HTTP message headers.

  44. Example HTTP Usage The start of the output of www.ietf.org/rfc.html.

  45. Caching Hierarchical caching with three proxies.

  46. Content Delivery Networks (a) Original Web page. (b) Same page after transformation.

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