CSCI 373 Computer Networking — Chapter 5 RPC

RPC — Remote Procedure Call

• The source — /usr/include/rpc/rpc_msg.h
• Pairs of distinguishing terms
  • stateless vs stateful
  • Synchronous vs asynchronous
• Examples from the 2000’s
  • ONC & DEC RPC
  • Java RMI
  • CGI — Common Gateway Interface

Common Gateway Interface

CGI is documented in RFC 3875.

Try out Professor Poopypants’ unauthorized name changer to test a classy CGI script. You should also take a look at the Perl CGI script.

Actions

• Caller loads a web page using GET or POST
• HTTP server invokes the CGI script
• CGI script writes a response (return value)
• HTTP server returns response
• Cookies can encode state information, for example, a shopping cart

API’s

CGI API’s are defined for more programming languages.

• Perl CGI
• Python
  • cgi
  • Cookie

AJAX

Ajax, for asynchronous JavaScript and XML is another RPC-like communication mechanism. Though originally designed with XML as the object encoding, JSON is more popular today. In CSCI 344, Ajax will be used with jQuery. We’ll leave that to CSCI 344, and just look at the look at the XMLHttpRequest Living Standard. Perhaps someone who took CSCI 344 a couple of years ago will be able to say more and give the instructor a little REST.

Many useful API’s, such as those of Twitter, are based on REST.