TCP IP Illustrated

Client interrupt a problem similar to flow control

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Unformatted text preview: ings/bigini/Documenti/homenet2run/tcpip/tcp-ip-illustrated/telnet.htm (4 of 26) [12/09/2001 14.47.45] Chapter 26. Telnet and Rlogin: Remote Login Sometimes, however, the application running on the server needs to interpret each byte of input, and doesn't want the client looking at the input bytes and treating Control-S and Control-Q specially. (The emacs editor is an example of an application that uses these two characters for its own commands.) To handle this, the capability is provided for the server to tell the client whether or not to perform flow control. Client Interrupt A problem similar to flow control occurs when we type the interrupt key (often DELETE or Control-C), to abort the process currently running on the server. The scenario is similar to what we show in Figure 26.3, with up to one window full of data in the pipe from the server to the client, while the interrupt key makes its way across the connection in the other direction. We want the interrupt key to terminate what's being displayed on the screen as quickly as possible. In both this case and the flow control scenario, it is rare for the flow of data from the client to the server to be stopped by flow control. This direction contains only characters that we type. Therefore it is not necessary for these special input characters (Control-S or interrupt) to be sent from the client to the server using TCP's urgent mode. Window Size Changes With a windowed display we can dynamically change the size of the window while an application is running. Some applications (typically those that manipulate the entire window, such as a full-screen editor) need to know these changes. Most current Unix systems provide the capability for an application to be told of these window size changes. With remote login, however, the change in the window size occurs on the client, but the application that needs to be told is running on the server. Some form of notification is required for the Rlogin client to tell the server that the window size has changed,...
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This test prep was uploaded on 04/04/2014 for the course ECE EL5373 taught by Professor Guoyang during the Spring '12 term at NYU Poly.

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