How many bytes of strings can be sent at once？

saiyxin · ‎11-02-2021

Hello，

When I use DDS write to send bytes of strings，I set forceUnboundedString? to True in order to send large data strings. I found when I set the bytes to 64983, it can be read out from another computer, but when I set to 64984, it cann't be read out. So how many bytes of strings can be sent at once and read from other reader？What QoS may have influence on it？

ismaelrti · ‎11-02-2021

Hi Saiyxin,

By default the property parent.message_size_max is set to 65536. That limits the size of data the transport t can receive. Looks like your type is over the maximum (some overhead is added). That limit can be customized by transport through QoS. Here is an example of how to do it UDPv4 and shared memory.

<participant_qos>
...

<property>
<value>


<element>
<name>dds.transport.UDPv4.builtin.parent.message_size_max</name>
<value>65530</value>
</element>
<element>
<name>dds.transport.UDPv4.builtin.send_socket_buffer_size</name>
<value>65530</value>
</element>

...


<element>
<name>dds.transport.shmem.builtin.parent.message_size_max</name>
<value>65530</value>
</element>
<element>
<name>dds.transport.shmem.builtin.receive_buffer_size</name>
<value>65530</value>
</element>
<element>
<name>dds.transport.shmem.builtin.received_message_count_max</name>
<value>32</value>
</element>

</value>
</property>

...
</participant_qos>

Also, the receiver buffer size can be changed:

<participant_qos>
...
<receiver_pool>
<buffer_size>65530</buffer_size>
</receiver_pool>
...
</participant_qos>

You can increase the maximum size to accommodate your data type. Have a look at the "message_size_max" property and other ones related related properties in the user's manual:

https://community.rti.com/static/documentation/connext-dds/6.1.0/doc/manuals/connext_dds_professiona...

RTI DDS Toolkit for LabVIEW Support

How many bytes of strings can be sent at once？

How many bytes of strings can be sent at once？

Re: How many bytes of strings can be sent at once？