[erlang-questions] io:request/2 documentation?

Robert Virding rvirding@REDACTED
Tue Mar 17 20:54:10 CET 2009

Hi Jeff,

No io:request/2 has not been documented yet. All it does is to send off a
request to an io-server and wait for the reply. One reason for not having
documented it is that up until very recently the io-server protocol has not
been documented.

This has now changed. In January I wrote a description of the older
io-server protocol. This description was included in my Erlang Rationale
document which you can find in the User Contributions section of
trapexit.org. A truly brilliant piece of writing. .-) There is now also a
freshly written description of the newer io-server protocol which is
included in the documentation of the just released version R13-A in the
user's guide section of stdlib. The newer protocol is very similar to the
older one, the main change is providing for some extra parameters for
handling unicode.

You use io:request/2 in the same manner as it is shown in the leex and yecc
blogg. A very good description by the way.

It can *NOT* be directly used with a gen_tcp generated socket. An io-server
is a process which obeys the io-server protocol. It would, however, not be
very difficult to write an io-server which could directly read/write against
a gen_tcp socket. If someone could show me a preferred way of setting up and
talking to a socket I can fix the io-server.

Hope this helps a little,


2009/3/17 jm <jeffm@REDACTED>

> Reading up on Leex and Yeec at
> http://hopper.squarespace.com/blog/2008/5/29/leex-and-yecc.html and it
> makes use of io:request/2 in one example. Yet there doesn't appear to
> any documentation for io:request/2. Is this another undocumented OTP
> function for insiders? Can this be used with a socket generated by
> gen_tcp? (I'm guessing not) and, if not, is there a suitable substitute
> for use with a tcp socket?
> Thanks,
> Jeff.
> _______________________________________________
> erlang-questions mailing list
> erlang-questions@REDACTED
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