What is the Robustness Principle?

On Thursday, June 26, 2003, at 11:21 AM, Hoffman, Geoffrey wrote:
> Jon Hanna wrote:
>> Following the robustness principal is NOT sloppy. Depending on it is.
> Maybe I missed it - what's the robustness principal? (principle?)
> Geoff

Robustness Principle was defined (among other places) in RFC 793 [1]
with more discussion in e.g. RFC 1122 [2]:

"TCP implementations will follow a general principle of robustness:
  be conservative in what you do, be liberal in what you accept from

"Adaptability to change must be designed into all levels of Internet
  host software.  As a simple example, consider a protocol specification
  that contains an enumeration of values for a particular header field
  -- e.g., a type field, a port number, or an error code; this
   enumeration must be assumed to be incomplete.  Thus, if a protocol
   specification defines four possible error codes, the software must
   not break when a fifth code shows up.  An undefined code might be
   logged (see below), but it must not cause a failure."

There's some interesting discussion of it here:


More stuff via google:




[1] http://deesse.univ-lemans.fr:8003/Connected/RFC/793/17.html
[2] http://deesse.univ-lemans.fr:8003/Connected/RFC/1122/9.html

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Received on Thursday, 26 June 2003 16:03:55 UTC