Download
networked applications n.
Skip this Video
Loading SlideShow in 5 Seconds..
Networked Applications PowerPoint Presentation
Download Presentation
Networked Applications

Networked Applications

169 Views Download Presentation
Download Presentation

Networked Applications

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. Networked Applications Chapter 11Updated January 2009 Raymond Panko’sBusiness Data Networks and Telecommunications, 7th edition May only be used by adopters of the book

  2. Client Program Server Program Client/Server Computing • The client does at least some of the work Client PC Server

  3. Client Program Server Program Client PC 11-2: Client/Server Computing 3 Client/Server Processing with Request-Response Cycle Request Message Response Message Does Light I/O and Post-Download Processing Does Heavy Database and Other Heavy Processing File Server Use larger server as number of clients increases

  4. Client is Browser Server Program 11-3: Web-Enabled Application HTTP Request Message HTTP Response Message Web-enabled applications: Form of client server processing that uses browsers as clients. Almost all client PCs now have browsers. No need to install new software. Client PC E-Mail Server

  5. E-Mail

  6. The E-Mail Delivery Process Receiver’s Mail Server Sender’s Mail Server Each e-mail user has a mail server. The sender transmits a message to its mail server. The sender’s mail server delivers the message to the receiver’s mail server. The receiver’s mail server delivers the message to the receiver. Sending E-Mail Client Receiving E-Mail Client

  7. 11-5: E-Mail Standards: Sending 2. SMTP To Send 1. SMTP To Send Receiver’s Mail Server Sender’s Mail Server Simple Mail Transfer Protocol (SMTP) is used to transmit mail in real time to a user’s mail server or between mail servers Sender-initiated Sending E-Mail Client (Outlook, etc.) Receiving E-Mail Client (Outlook, etc.) Note that SMTP provides immediate delivery—usually in a few seconds.

  8. 11-5: E-Mail Standards: Receiving 3. POP or IMAP to Receive Receiver’s Mail Server Sender’s Mail Server POP or IMAP to download mail to receiver when the receiver next downloads mail Receiver-initiated Receiving E-Mail Client (Outlook, etc.) Sending E-Mail Client (Outlook, etc.)

  9. 11-5: E-Mail Standards: Web-Based E-Mail SMTP HTTP SMTP POP or IMAP On the left, we have just seen that traditional e-mail clients send with SMTP and receive with POP or IMAP. On the right, Web-based e-mail clients only need a browser and use HTTP both to send and to receive. Server-server communication always uses SMTP. Web-Based E-Mail Client Browser Traditional E-Mail Client (Outlook, etc.)

  10. HTML and HTTP

  11. 11-7: HTML and HTTP The Hypertext Transfer Protocol (HTTP) is the standard for transferring messages between the client (browser) and the server (webserver). The Hypertext Markup Language (HTML) is a standard for text documents that have tags to indicate formatting and other files to be downloaded

  12. Peer-to-Peer Computing

  13. Client PC Client PC Client PC Client PC Client PC 11-15: Traditional Client/Server Application Disadvantages: Network Overload at Server Underused Client Power Central Control Advantage: Central Control Server Does Heavy Processing Work

  14. P2P Applications • Direct service, although most P2P systems use facilitating servers for some of the work Peer Peer Peer Peer Peer Peer

  15. Client PC Client PC Figure 11-16: Simple Peer-to-Peer (P2P) Application Request Response Benefits: End User Freedom No Network Bottleneck at Server Uses Client Capacity Better Problems: Transient Presence of Clients Transient Client IP Addresses Security (No Central Control)