[Tinyos-help] Re: connecting to the SerialForwarder

[Javier Barbarán]

The way to receive data from SerialForwarder (c-based version 
partiularly, but also any version) is to implement the whole protocol 
(check the code, it's more than you are doing). Once you have negotiated 
properly the SerialForwarder protocol, the SerialForwarder protocol will 
send you first one byte that is the length in bytes of the next message 
and following the message.

You can also take a look to this paper where we have defined a (very 
basic) sequence diagram of the SerialForwarder protocol.
http://www.waset.org/proceedings/v21/v21-29.pdf


Hope this help...


Islam Hegazy escribió:
> What I understand from the code is how to interpret the data not how 
> to receive it. My problem is that my client receives 'T!' only. I have 
> the following changes but nothing new happens. It stops at the second 
> recv waiting for data to arrive:
>
> if ((rcd = recv(sd, s, 2, 0)) != 0)
>
> {
>
>    if (s[0] == 'T' && s[1] == '!')
>
>    {
>
>        char byte[4];
>
>        recv(sd, byte, 4, 0);
>
>        char data[20];
>
>        int offset = 0;
>
>        while (offset < 20)
>
>        {
>
>            int count = recv(sd, data, 20 - offset, 0);
>
>            if (count == -1)
>
>                shutdown(sd, SHUT_RD);
>
>            offset += count;
>
> }
>
> }
>
> }
>
> Regards
>
> Islam
>
> ----- Original Message ----- From: "Javier Barbarán" 
> <barbaran at lcc.uma.es>
> To: "Islam Hegazy" <islheg at gmail.com>; 
> <tinyos-help at Millennium.Berkeley.EDU>
> Sent: Monday, June 04, 2007 1:16 PM
> Subject: Re: connecting to the SerialForwarder
>
>
>> Hello,
>>
>> I mean that you have to take a look to the class that I mentioned in 
>> my last mail. There you will see that in order to connect to 
>> SerialForwarder application (I remember that you were using c-based 
>> version) you have to follow a specific protocol (implemented in 
>> SFProtocol java class) where you receive 'T!' that is the begining of 
>> the protocol. So if you look to the server side in SerialForwarder 
>> you will be able to see how to implement the protocol.
>>
>> The following code is part of sfsource.c file, part of c-based 
>> serialforwarder that you are already using.
>>
>>
>> int init_sf_source(int fd)
>>   95 /* Effects: Checks that fd is following the serial forwarder 
>> protocol
>>   96      Sends 'platform' for protocol version '!', and sets 
>> 'platform' to
>>   97      the received platform value.
>>   98    Modifies: platform
>>   99    Returns: 0 if it is, -1 otherwise
>>  100  */
>>  101 {
>>  102   char check[2], us[2];
>>  103   int version;
>>  104   unsigned char nonce[4];
>>  105   /* Indicate version and check if serial forwarder on the other 
>> end */
>>  106   us[0] = 'T'; us[1] = '!';
>>  107   if (safewrite(fd, us, 2) != 2 ||
>>  108       saferead(fd, check, 2) != 2 ||
>>  109       check[0] != 'T' || check[1] < ' ')
>>  110     return -1;
>>  111 112   version = check[1];
>>  113   if (us[1] < version)
>>  114     version = us[1];
>>  115 116   switch (version)
>>  117     {
>>  118     case ' ': break;
>>  119     case '!':
>>  120       nonce[0] = platform;
>>  121       nonce[1] = platform >>  8;
>>  122       nonce[2] = platform >> 16;
>>  123       nonce[3] = platform >> 24;
>>  124       if (safewrite(fd, nonce, 4) != 4)
>>  125 return -1;
>>  126       if (saferead(fd, nonce, 4) != 4)
>>  127 return -1;
>>  128       //Unlike the more general SFProtocol.java this piece of 
>> code always knows what platform it is connected to; just   drop the 
>> preferred platform from the client
>>  129 //platform = nonce[0] | nonce[1] << 8 | nonce[2] << 16 | 
>> nonce[3] << 24;
>>  130       break;
>>  131     }
>>  132 133   return 0;
>>  134 }
>>
>>
>> Islam Hegazy escribió:
>>> Hi
>>>  What do you mean by following the SerialForwarder protocol? I 
>>> create a socket and connect it to the SF but I only receive T!- . I 
>>> did another client on Windows using C# and I did the same steps but 
>>> it receives normally through the socket...
>>>  Regards
>>> Islam Hegazy
>>>
>>>     ----- Original Message -----
>>>     *From:* Javier Barbarán Sánchez <mailto:barbaran at lcc.uma.es>
>>>     *To:* islheg at gmail.com <mailto:islheg at gmail.com> ;
>>>     tinyos-help at Millennium.Berkeley.EDU
>>>     <mailto:tinyos-help at Millennium.Berkeley.EDU>
>>>     *Sent:* Monday, June 04, 2007 2:03 AM
>>>     *Subject:* connecting to the SerialForwarder
>>>
>>>     Hello
>>>      You must follow the SerialForwarder protocol, you can take a look
>>>     on it in
>>>     <tinyos_directory>\tools\java\net\tinyos\packet\SFProtocol.java
>>>      Good luck
>>>
>>
>
>