Re: [Owfs-developers] owserver protocol

[Stefano M. <mo...@ic...>]

Sorry for the confusione between message payload and message size… I forgot about this difference: https://github.com/owfs/owfs/blob/d0c3abac8f16d38c0fe5fb9e0c62c57f2e6696fb/module/owlib/src/include/ow_message.h#L45-L63 <https://github.com/owfs/owfs/blob/d0c3abac8f16d38c0fe5fb9e0c62c57f2e6696fb/module/owlib/src/include/ow_message.h#L45-L63>
(but in most cases payload == size, or payload == size+1 to accomodate for a terminating null byte)

So I confirm: headers with payload == -1 are to be discarded and the client should continue waiting for the answer.

S.

> On 5 Mar 2017, at 21:08, Colin Law <cl...@gm...> wrote:
> 
> The extra header contains version: 0, payload: -1, ret: 0, flags: 0,
> size: 0, offset: 0
> So the element described as size of data element is 0 though that
> described as length of payload data is -1.
> 
> Colin
> 
> On 5 March 2017 at 19:34, Colin Law <cl...@gm...> wrote:
>> Can I just check there I not a confusion here, I am talking about comms
>> between client and owserver, not between server and sensor.
>> 
>> On 5 Mar 2017 6:43 p.m., "Stefano Miccoli" <mo...@ic...> wrote:
>>> 
>>> What you describe (0-size payload message followed by another valid
>>> message) cannot happen.
>>> May be what you really mean is a -1 size payload message? This is a “ping”
>>> which owserver sends every 1 second or so when it is still gathering data or
>>> under heavy payload.
>>> 
>>> This is an aspect of the owserver protocol which easily gets unnoticed by
>>> implementers: please see https://github.com/miccoli/pyownet/pull/1 where
>>> Johan Ström corrected a similar bug in my pyownet.
>>> 
>>> S.
>>> 
>>> On 5 Mar 2017, at 17:51, Colin Law <cl...@gm...> wrote:
>>> 
>>> I am trying to debug a problem on the node.js owserver client
>>> node-owfs and am looking for some clarification of the owserver
>>> protocol if possible please.
>>> 
>>> Referring to [1] in response to a 1-wire read I expect to see a header
>>> with a payload of the size indicated in the header. Very often what I
>>> actually see is a header specifying a payload size of 0 followed by
>>> another header with the expected payload size and valid data.  Is that
>>> normal or is there something strange going on?
>>> 
>>> This is owserver 3.1p4-1 from the raspbian jessie testing repository
>>> on a pi zero.
>>> 
>>> [1] http://owfs.org/index.php?page=owserver-protocol
>>> 
>>> Colin
>>> 
>>> 
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>> 
> 
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