Re: [opendds-main] Problem with QoS Policies

[Alex D. <ale...@gm...>]

Hello,

First of all thank you for your help. It finally worked after changing
to TCP transport. I was using RTPS UDP in my rtps.ini file as below :

[common]
DCPSGlobalTransportConfig=my_config
DCPSDefaultDiscovery=DEFAULT_RTPS

[config/my_config]
transports=rtps_transport

[transport/rtps_transport]
transport_type=rtps_udp
use_multicast=0

and the only change I did in my rtps.ini was the transport type from
"rtps_udp" to "tcp"

A question that rose after this change :
Isn't this configuration now preventing the application for being
interoperable with other DDS implementations ? I am asking because in
the OpenDDS Developers Guide states "The rtps_udp transport is one of
the pluggable transports available to a developer and is necessary for
interoperable communication between implementations." Is there any way
to keep interoperability and use TCP transport as well ?

Regards,
Alex

On Mon, Dec 1, 2014 at 6:18 PM, Jeff Schmitz <sch...@oc...> wrote:
> Hi Alex,
>
> A few points
>
> 1. In the subscriber, it is not enough to check the status of take_next
> sample().  You should also check info.valid_data
>
> 2. In the publisher, if you want it to behave reliably, change the history
> kind to KEEP_ALL_HISTORY_QOS, and use resource limits to control the number
> of samples in history.  Then check for a timeout status from the write()
> call.  See the Reliability example.
>
> 3. Use TCP transport, if you are not.  It is the most trusted transport of
> OpenDDS
>
> If this does not fix your problem, I'd suggest starting with the reliability
> example, and working your way back to your example to see the difference.
>
> jeff
>
> On Thu, Nov 27, 2014 at 3:02 AM, Alex Douckas <ale...@gm...> wrote:
>>
>> Hello,
>>
>> I have created a publisher application and a subscriber one ( both in
>> C++ ) with the following QoS policies on both Topic and DataWriter (
>> and DataReader respectively ) :
>>
>> DDS::TopicQos default_topic_qos;
>> participant->get_default_topic_qos(default_topic_qos);
>> default_topic_qos.history.kind = DDS::KEEP_LAST_HISTORY_QOS;
>> default_topic_qos.history.depth = 140000;
>> default_topic_qos.reliability.kind = DDS::RELIABLE_RELIABILITY_QOS;
>>
>> DDS::DataWriterQos dw_default_qos;
>> pub->get_default_datawriter_qos (dw_default_qos);
>> dw_default_qos.history.kind = DDS::KEEP_LAST_HISTORY_QOS;
>> dw_default_qos.history.depth = 140000;
>> dw_default_qos.reliability.kind = DDS::RELIABLE_RELIABILITY_QOS;
>>
>> Now, the publisher is sending about 3000 data samples, each one every
>> 100 miliseconds. So to test the history and reliability policies, I
>> set a delay on the subscriber ( with usleep) of 500 miliseconds on the
>> "on_data_available" class like this :
>>
>>       DDS::SampleInfo si ;
>>       DDS::ReturnCode_t status = measurement_dr->take_next_sample(data,
>> si) ;
>>
>>       if (status == DDS::RETCODE_OK) {
>>          //omitted Code that manipulates the data sample
>>
>>              usleep (500000);
>>
>>        } else if (status == DDS::RETCODE_NO_DATA) {
>>         cerr << "INFO: reading complete after " << count << " samples." <<
>> endl;
>>         break;
>>       }
>>
>> The problem is that after about 1000 received samples, the subscriber
>> somehow stops receiving the rest samples. Since the depth of History
>> is bigger than the samples, the subscriber should receive everything.
>> The same thing happens even if I use KEEP_ALL_HISTORY instead of
>> KEEP_LAST. Do you have any idea about this issue ?  Am I using the
>> policies wrong ?
>>
>> Thanks,
>> Alex
>>
>>
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>
>
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