Question

Persistent and non-persistent HTTP (40 points). In the previous problem, suppose the base HTML references 9 very small objects on the same server. Neglect transmission times. Determine in each case below, (1) how much time elapses from when the client clicks on the link until the client receives the web page (i.e., all the objects, including the base and all referenced objects)? (2) how many TCP connections are opened? (a) non-persistent HTTP with no parallel TCP connections? (b) non-persistent HTTP with three parallel TCP connections? (c) persistent HTTP without pipelining? (d) persistent HTTP with pipelining?

Answer 1

Time and connections for HTTP scenarios:

a) Non-persistent HTTP, no parallel connections:

Time: 10 * Download Time (10 downloads for 1 base page and 9 referenced objects)

Connections: 10 (one for each object)

b) Non-persistent HTTP, 3 parallel connections:

Time: 1.333 * Download Time (3 parallel downloads + 4 sequential downloads + 3 final downloads)

Connections: 10 (one for each object)

c) Persistent HTTP, no pipelining:

Time: 1 * Download Time (1 download for base page + 9 sequential downloads)

Connections: 1 (single connection reused)

d) Persistent HTTP, pipelining:

Time: 1 * Download Time (all objects downloaded in one request)

Connections: 1 (single connection reused)