Internet components and workflow

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From Browser to web server

Browser WebServer.jpg

  1. User using browser to access URL. For example:
  2. Browser query DNS and gets IP address.
  3. It may need to connect to Paypal later on.
  4. Connect to ISP --> Internet --> the IP address
  5. Router and Firewall only allow Web traffic
    • Router calling the Web Server in the (internal) LAN
  6. Web server running LAMP (Linux, Apache, MySQL, PHP)

Internet Shopping

Internet Shopping FlowDiagram.jpg

  1. User enter URL and calling web server (above)
  2. Web server returns HTML (either static or PHP dynamically generate)
  3. Web server also send either JavaScript or Flash code to the browser
  4. User interact with Browser elements
  5. Browser uses AJAX calls to get more information from backend to browser
  6. Web Server get the information from DB
  7. User submits charge information
  8. Web server redirect the user to PayPal web site to verify the payment
  9. PayPal confirm the payment
  10. Web Server saves the transaction into DB.
  11. Notify the user the transaction status

Email Flows

Mail flows.pdf

  • Blue colour is the sender side setup.
  • Red colour is the receiver side setup.
  • The others are the Email relay help servers.
  1. Sender
    • Sender create an email and use email client to send it to the submission server.
    • Submission server send to outbound server to send / re-try emails.
      • An email can have multiple precipitants with different domain name.
  2. Reciver
    • Receiving incoming email
    • Save the emails (messages) into the email server.
    • User email client read the email from server.