[openrtm-users 03079] Re: Is RTC::TimedStringSequence to bytestream conversion a well defined function?

[Geoffrey Biggs]

Hi Atilla,

On 30 July 2014 21:55, Attila Bernáth <attila.bernath ＠ sztaki.hu> wrote:

> > packing and unpacking the data, the TimeString structure contains a time
> > member, which you are not setting anywhere and so will contain
> uninitialised
> > values when you put it into the byte string.
> I am afraid I don't understand this part.
> In the code I attached the TimedStringSeq data is obtained from some
> byte array using the cdrmemorystream interface.
> I obtained this byte array from some TimedStringSeq data: in that I
> set the time member.
> Can you explain a bit better, please?
>
>
The byte stream contains data that has been converted so that it can be
transmitted to other entities that want to use it. These may be programs on
the same computer, or on another computer using the same OS and CPU, etc.,
or they may be on a completely different type of computer. This means that
the data is altered a little or a lot depending on how different the way
data is structured by the memory, CPU, OS, data packing software, etc.
that are in use is from how data is structured by the platform-neutral
transport. Even if you fill in all the data fields, that does not mean that
the packed data will be identical every time.

In general, if you get the same data out that you put in, you do not need
to worry about what the packed data looks like. Only worry about that if
you start getting different data out and you are debugging the data
transport.

I agree that it is interesting to know how all this stuff works internally,
but in this case the best place you can look for information is the CORBA
specification's section on the Inter-Orb Protocol.

Geoff
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