[PROTON-317] Feature Enhancement - API Exposure of underlying references to internal atoms

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: proton-0.3
• Fix Version/s: proton-0.5
• Component/s: proton-c
• Environment: Linux / C implementation
• Assignee: Rafael H. Schloming
• Reporter: Frank Quinn
• Created: 24/May/13 18:32
• Updated: 07/Jan/16 11:33
• Resolved: 05/Aug/13 18:28

Description

We're currently creating a pn_message_t and iterating over it using the pn_data_t data type and the various convenience methods surrounding it. This is great for iteration but we were also hoping to have a way to mark a point in the payload for future realignment. I looked at get_message_id() but that always seems to return NULL.

Let's take a pseudo example:

pn_data_rewind (pn_data);
while (pn_data_next (pn_data))
{
pn_atom_t atom = pn_data_get_atom (pn_data);
if(this_atom_might_be_useful)

{ // Mark this for potential modification later }

}

if (changes_are_required_based_on_a_combination_of_circumstances)
{
// Jump to earlier marker(s)

// put in relevant update(s)
}

Is there anything we could use for this sort of use case? I want to avoid having to iterate again to find values, and I also want to be able to write functions which don't move (or move, then reset) the internal buffer pointers in proton. If there was something like a get_position() or set_position(), that would be perfect.