Final end of GSoC 2012

Today is firm "pencils down" date, so it's time for summary of work done in last 3 months. I learned a lot during this time and I hope I will be able to work on any GSoC project next year again.
As you know this summer I worked on whiteboarding feature of Swift which is XMPP based chat client. UI side wasn't very demanding and I think the hardest part was the synchronization protocol. There is no standard whiteboard protocol approved by XSF, so I needed to create my own. Remko(my mentor) wanted to use Operational Transformation to keep clients in sync. The problem was that descriptions of OT which I found didn't covered everything. I needed to find own universal method to compute relevant operations for different situations. It took me a while to understand everything and implement it, but final whiteboard works quite nice thanks to that algorithm.  Whole protocol has been implemented in Swiften library, so it could be easily reused in other clients using this library. At this time only one-to-one sessions are supported, but I will try make it work with MUCs after GSoC. I will also have to finish up my XEP, which so far contains descriptions of 4 situations and general way of computing relevant operations.

Suggested pencils down time

Last week I worked a little with XEP describing my protocol and then I focused on changes changes proposed by Remko. I changed texts informing about session status, added button to cancel whiteboard request, added "Opened whiteboards" section to chats tab(which allows to see opened whiteboard chats and bring it up), added handling of sessions where one side goes offline, reorganized a little session handling code, "ifdefed" whiteboard code to include it only if experimental flag is set, finally added eraser icon and modified UI a little. At the end of the week I rebased my branch on master and did some final touches according to Remko's comments. He said that he suspects that whiteboard can be integrated quite soon after GSoC pencils down under experimental.

Final preparations

This week I implemented last missing functionality which is moving of elements up and down. I modified existing "update" operation so it now has newPos field. I tried to use as few as possible operations because of amount of transformation functions(They has to handle every combination). Besides that I also added some small fixes and started writing the XEP describing protocol which I've created. Its XML format is quite simple so it doesn't need much description, but whole protocol is largely based on on operational transformation algorithm which needs detailed description about how to handle specific situations.