COE 431 Problems 1, Fall 2013

Problem I: Assume that you want to retrieve a webpage that consists of 6 JPEG images and 1 Java applet. The Java applet retrieves 3 more images before it can run. 1. When using non-persistent HTTP, how many messages will the client and the server exchange before the entire webpage is received by the client’s host? How much time elapses from when the client requests the webpage until the entire webpage comes in? (Hint: express that amount of time as a function of the RTT) 2. How many messages must be sent when using persistent HTTP with no pipelining? How long would the client wait before the entire webpage is received (i.e., how many RTTs)? 3. How many messages would be sent if persistent HTTP with pipelining were used? How long does the client wait until it obtains the entire webpage (i.e., how many RTTs)? 1 Problem II: Suppose within your web browser you click on a link to obtain a web page. Further suppose that the web page associated with the link contains exactly one objet, consisting of a HTM text. Let RTT0 denote the RTT between the local host and the server containing the object. 1. Assuming zero transmission time of the object, how much time elapses from when the client clicks on the link until the client receives the requested object? 2. Suppose now that the HTML file references three very small objects on the same server. How much time elapses with a. Non-persistent HTTP with no parallel TCP connections? b. Non-persistent HTTP with parallel connections? c. Persistent HTTP? 2