[erlang-questions] encoding packets a style+efficiency question

[Anupam Kapoor]

yes i know. but my question was more towards a better approach towards
writing packet encoders/decoders. may you please let me know your
thoughts on that ?

kind regards
anupam

On Tue, Jul 26, 2011 at 7:08 PM, Kenneth Lundin
<kenneth.lundin@REDACTED> wrote:
> I suppose you arleady know that there is a tftp implementation included in the
> Erlang/OTP distribution.
>
> You find the documentation here.
> http://www.erlang.org/doc/man/tftp.html
>
> /Kenneth Erlang/OTP Ericsson
>
> On Tue, Jul 26, 2011 at 9:36 AM, Anupam Kapoor <anupam.kapoor@REDACTED> wrote:
>> hi all,
>>
>> i have been playing with an implementation of tftp
>> (rfc-1350). encoding/decoding tftp-pdu's is trivial with erlang's bit
>> syntax.
>>
>> there seem to be couple of approaches to encoding/decoding tftp-pdu's:
>>
>>   1. use native "in-place" encode/decode
>>   2. have a 'generic' encode/decode routine which accepts
>>         - a list of pdu primitives e.g. 'byte'/'string' etc. and
>>         - a list of corresponding values
>>      and returns the binary packet.
>>
>>      for example, encoding a tftp-data packet looks like this:
>>          ,----
>>          | %% encode data packet
>>          | encode_data_pkt(BlkNum, Data) ->
>>          |     encode_packet([?BYTE, ?BYTE, ?RAW],
>> [?TFTP_OPCODE_DATA, BlkNum, Data]).
>>          `----
>>
>> to me, approach #2 seems pretty close to rfc's packet-format
>> specification. for example, the data-packet is shown as
>>
>>           2 bytes     2 bytes      n bytes
>>           ----------------------------------
>>          | Opcode |   Block #  |   Data     |
>>           ----------------------------------
>>
>> can you please provide your suggestion on whether #2 might be a good
>> approach to follow for complicated protocols e.g. gtp-v2 which defines a
>> large number of messages ? also, are there better (increasing order of
>> readability, performance etc.) approaches for doing this ?
>>
>> thank you
>> kind regards
>> anupam
>>
>> ps: the attached file contains encoders for tftp messages...
>>
>> --
>> In the beginning was the lambda, and the lambda was with Emacs, and
>> Emacs was the lambda.
>>
>> _______________________________________________
>> erlang-questions mailing list
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>>
>>
>



-- 
In the beginning was the lambda, and the lambda was with Emacs, and
Emacs was the lambda.