Re: On intended use cases of the distributed annex

[Brad Moore <brad.moore@shaw.ca>]

On 14-09-25 02:30 AM, Maciej Sobczak wrote:
> W dniu środa, 24 września 2014 11:37:49 UTC+2 użytkownik Alejandro R. Mosteo napisał:
>
>> I was thinking about the possibility of requesting the installation of an Ada compiler in such cluster, and also if the DSA can fulfill my needs.
>
> You can make it work, but be aware that DSA was not invented with heterogeneous systems in mind. That is, the annex does not define the wire-level protocol nor even the data type mappings, so depending on the particular implementation you might be forced to use the same compiler version for all nodes and obviously all of the nodes will have to be written in Ada. This might sound like heaven for some, but in a distributed system it might as well become a maintenance and integration nightmare and if at the end you will have to use additional protocols for integration with existing software or for adding software written by others or for other functions like remote monitoring or configuration scripts, etc., then it will become a bloody mess, which kind of contradicts the intentions of using Ada in the first place. For this reason I would not use DSA at all and instead try some technology-neutral communication solution.
>
> I don't claim that the above considerations are bound to be problems, but certainly they are something to think about before you start.
>

Not quite true that all the nodes need to be written in Ada.  I have 
used DSA to send C++ objects to C++ applications (or at least objects of 
C++ classes that are derived from Ada types), and as well had C++ 
applications remotely interacting with each other C++ and other Ada 
applications using the DSA.
I also appreciate that the DSA is more closely integrated with the 
compiler, allowing the compiler to check and catch problems that a 
library only approach does not provide.