Transcript XML-RPC: How Fast ?

XML-RPC: How Fast ?
Brent Callaghan
Sun Microsystems, Inc.
My Background
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Experience with ONC RPC protocols
Participant in ONCRPC WG @ IETF.
NFS: high performance, kernel-based
NFS version 4 uses ONC RPC over the
Internet.
XML for Data Marshalling
• Everything is text:
<Name>Jane</Name><Age>3</Age>
• Convenient for text-oriented transports, e.g.
SMTP, HTTP
• Readable by humans (great when
debugging)
• Covenient if data already described by
XML
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.
HTTP as a Bottleneck
• Verbose HTTP headers on every call:
POST /StockQuote HTTP/1.1
Host: www.stockquoteserver.com
Content-type: text/xml
Content-Length: 1094
HTTP as a Bottleneck
• Calls funnel through web server on port 80.
• RPC service needs to be in web server
address space.
HTTP Server
Direct Connect
RPC
Server
RPC
Server
Port 80
Fork/exec
RPC
Server
Port 1234
Conclusion
• Don’t use XML-RPC
for performance-critical apps..