Sending byte array using DDS_Dynamic Data

Hi Andrei,

In the LabVIEW toolkit we do something similar. We need to map generic LabVIEW types into DDS types. For Unsigned Char we used DDS Octets. And the way to extract that typecode is calling the followign function:

DDS_TypeCode *tc = NULL;

tc = DDS_TypeCodeFactory_get_primitive_tc(factory,
DDS_TK_OCTET);

At least in C. And then you can create a sequence or an array of those elements. You could even create an unbounded sequence if you don't know the maximum size of the dataValue that you are going to obtain.

I hope this helps! Thanks,
Sara

Hi Andrei,

LabVIEW arrays can have variable size, so we detect the size of the array in LabVIEW at creation time and then create the DDS type accordingly. Then at run-time LabVIEW arrays could have different sizes and sequences will still work, but always to the maximum lenght established during creation. Or we make them unbounded if the user selects that option.

Do your origin type have a size defined at some point? Which technologies are you trying to bridge with DDS? 

Thanks,
Sara

Hi Andrei,

Actually, you just need to set the bound to the maximum integer (RTI_INT32_MAX) and that works. However, there are some issues with resources you may run into. For instance, I would recommend you setup the following QoS settings:

<datawriter_qos> 
    <property>
        <value>
            <element>
                <name>
                dds.data_writer.history.memory_manager.fast_pool.pool_buffer_max_size
                </name>
                <value>4096</value>
            </element>
        </value>
    </property>
</datawriter_qos>

<datareader_qos>
    <property>
        <value>
            <element>
                <name>
                dds.data_reader.history.memory_manager.fast_pool.pool_buffer_max_size
                </name>
                <value>4096</value>
            </element>
        </value>
    </property>
</datareader_qos>

In addition, when managing DynamicData, there are other settings to configure. I am working on a KB article with that additional information and on verifying this information, but here you have a summary of the ideas I would try:

struct DDS_DynamicDataTypeProperty_t prop = DDS_DynamicDataProperty_t_INITIALIZER;
prop.serialization.trim_to_size = DDS_BOOLEAN_TRUE;
prop.serialization.min_size_serialized =  DDS_LENGTH_UNLIMITED; //I need to verify this 
prop.serialization.max_size_serialized = DDS_LENGTH_UNLIMITED;

Please give it a try and let me know how it goes.

Thanks,
Sara

sorry to bother you, i want to dynamic create topic idl like this:
struct SimData {
long nRow;
long nCol;
char Data[16];
};
i don't know how to create member "char Data[16]", its an array of primitive char type. i use the codes in the fowllowing:
struct DDS_UnsignedLongSeq dimensions;
DDS_TypeCode* sz = DDS_TypeCodeFactory_create_array_tc(factory, &dimensions, DDS_TypeCodeFactory_get_primitive_tc(factory, DDS_TK_CHAR), &ex);
if (ex != DDS_NO_EXCEPTION_CODE)
{
return NULL;
}

DDS_TypeCode_add_member(portTc, "Data", DDS_MEMBER_ID_INVALID, sz, DDS_TYPECODE_NONKEY_REQUIRED_MEMBER, &ex);
if (ex != DDS_NO_EXCEPTION_CODE)
{
return NULL;
}
i know the variable dimensions is not setting correctlly. can you help me?

I got the way to solve it, there are functions for creating it, like this

DDS_UnsignedLongSeq_initialize

DDS_UnsignedLongSeq_ensure_length

DDS_UnsignedLongSeq_get_reference

DDS_UnsignedLongSeq_finalize

Hi Andrei,

Sorry I forgot to mention that.  You have to add that when creating the TypeSupport for your DynamicData:

typeSupport = DDS_DynamicDataTypeSupport_new(typeCode, &prop);

Thanks,

Sara

Hi all,

I have the following IDL definition:

file.idl:
---
module idlModule {
struct idlDataTopic {
int dataType;
int dataSize;
string<4096> dataValue;
};
}
---
So I use the autogenerated code by rtdddsgen to compound the data to publish.

And dataValue should accept several different C structs. Now it is a string but I guess it is not the correct aproach.

Can I use your solution about DynamicData only for dataValue and still use at the same time the code autogenerated by rtdddsgen for the rest of topic?

Best regards,

Luis.