DataDDX

• Use a multipart MIME document to hold the DDX and one or more data blobs. ADopt the same use of M. MIME as WCS uses.
• consider the following design idea for embedding type information within the data stream:

In DAP2, the DDS is used as a descriptive header for data. For gridded data that works OK but for point data it doesn't work so well. When the data are read as from a stream, it's OK, but when the data are read and stored, then used, they need to be in a linked structure. Because the DDS contains the data type definition and not the value, it does not hold a structure suitable for holding values. Look at how the d_values field in Sequence works (see Sequence::print_val(), deserialize()). A better approach would be to encode the type of a variable in the data stream itself and have the reader (client most of the time) build instances as needed. For arrays, structures and simple types this is mostly a wash, but for Sequences it would be a major plus because the protocol could support sequences of complex objects more easily. It would also get rid of the odd situation where a DDS holds a type definition for a nested sequence while the top-most sequence holds the tree of objects which hold values. (I.E. the child sequences in the DDS don't hold data at all).

As an alternative, suppose we build a data response using the DDX in a multipart document and then encoded type information in the data stream as well? This would provide a way to bundle attributes with variables in the data response and locate type information with the data values (for sequences mostly).