Hi Andre,
here is the updated draft of the SAGA Message API, in preparation for OGF-19. It is also available in CVS, as usual.
We would be happy to get feedback on the list of course, so don't feel oblidged to hold back your comments for OGF-19 :-)
Sorry, it took me some time to digg through the new spec... I had to start implementing the stuff to have comments (I'm perhaps too old to do programming other than in an intuitive way :-P). The comments I have relate to the API part of the spec. Frankly, I don't like the design of the 'msg' object, I even think it's not viable to make it a first class SAGA object (derived from saga::object) - is there a use case requiring that? The msg object in its current design mixes two different paradigms into one object (remember: every kind of bool in an API is a strong hint for a flawed design): a) saga::msg can be a wrapper object for application memory (size > 0) and b) saga::msg can be a object managing memory on behalf of the SAGA implementation (size == -1) I strongly believe that we don't need b) and even if we do, it should be implemented in a separate abstraction. Why do I think we don't need b)? Instead of relying on the SAGA implementation to manage the memory for the application (BTW: this is the only instance in the whole spec, where we require the implementation to do this), an application always may write (syntax is C++): endpoint ep(...); ep.connect(...); int size = 0; if (ep.test(..., &size)) { void *data = new unsigned char[size]; ep.recv(data, size); Or even better: ep.recv(buffer(data, size)); ... delete data; } i.e. The application always can handle the memory itself, without having to go through too much overhead. This brings me to the second comment: by implementing the msg/buffer object solely for the purpose of wrapping up application memory this msg/buffer could be reused for other packages as well: file::read, file::write, stream::read, stream::write, rpc::parameter::buffer - to name a few. BTW: I silently introduced a const_buffer and mutable_buffer objects, combined with a buffer() generator function in the C++ implementation of the saga::file package to improve memory handling in the API. Regards Hartmut