XMLRPC: How Fast

1
XML-RPC How Fast ?

• Brent Callaghan
• Sun Microsystems, Inc.

2
My Background

• Experience with ONC RPC protocols
• Participant in ONCRPC WG _at_ IETF.
• NFS high performance, kernel-based
• NFS version 4 uses ONC RPC over the Internet.

3
XML for Data Marshalling

• Everything is textltNamegtJanelt/NamegtltAgegt3lt/Agegt
• Convenient for text-oriented transports, e.g.
  SMTP, HTTP
• Readable by humans (great when debugging)
• Covenient if data already described by XML

4
XML for Data Marshalling

• Tags and ASCII make it fat w.r.t binary protocols
  like XDR.
• Needs approx twice as many bytes.
• Binary args or results need Base64 encoding (as
  text)
• Significant effect on modem or wireless links.
• Text takes time to parse
• More CPU instructions per transaction implies
  more CPUs for a given level of service.

5
HTTP as a Bottleneck

• Verbose HTTP headers on every callPOST
  /StockQuote HTTP/1.1Host www.stockquoteserver.co
  mContent-type text/xmlContent-Length 1094

6
HTTP as a Bottleneck

• Calls funnel through web server on port 80.
• RPC service needs to be in web server address
  space.

HTTP Server
RPC Server
RPC Server
Port 80
RPC Server
Fork/exec
7
Conclusion

• Dont use XML-RPC for performance-critical apps..