1. CS 194: Distributed Systems WWW and Web Services Scott Shenker and Ion Stoica Computer Science Division Department of Electrical Engineering and Computer Sciences University of California, Berkeley Berkeley, CA 94720-1776
2.
3.
4.
5.
6.
7.
8.
9. Big Picture Client Server TCP Syn TCP syn + ack TCP ack + HTTP GET Establish connection Request response Client request Close connection . . .
10.
11.
12.
13. Server Response HTTP/1.0 200 OK Content-Type: text/html Content-Length: 1234 Last-Modified: Mon, 19 Nov 2001 15:31:20 GMT <HTML> <HEAD> <TITLE>EECS Home Page</TITLE> </HEAD> … </BODY> </HTML>
14. HTTP/1.0 Example Client Server Request image 1 Transfer image 1 Request image 2 Transfer image 2 Request text Transfer text Finish display page
27. Example: Akamai get http://www.nhc.noaa.gov a DNS server for nhc.noaa.gov b c local DNS server www.nhc.noaa.gov “ Akamaizes” its content. “ Akamaized” response object has inline URLs for secondary content at a128.g.akamai.net and other Akamai-managed DNS names . akamai.net DNS servers Akamai servers store/cache secondary content for “Akamaized” services. lookup a128.g.akamai.net
28.
29.
30.
31.
32. A trivial HTML document <HTML> <HEAD> <TITLE> My web page </TITLE> </HEAD> <BODY> Welcome to my webpage! This is on the same line. </BODY> </HTML> HTML HEAD BODY Welcome to my webpage! This is on the same line. TITLE My web page Nesting structure
51. SOAP Request <SOAP-ENV:Envelope xmlns:SOAP-ENV=“http://schemas.xmlsoap.org/soap/envelope/” SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/”> <SOAP-ENV:Header> <t:transId xmlns:t=“http://a.com/trans”>345</t:transId> </SOAP-ENV:Header> <SOAP-ENV:Body> <m:Add xmlns:m=“http://a.com/Calculator”> <n1>3</n1> <n2>4</n2> </m:Add> </SOAP-ENV:Body> </SOAP-ENV:Envelope> Scopes the message to the SOAP namespace describing the SOAP envelope Establishes the type of encoding that is used within the message (different data types supported)