New Feature Implemented: Handling of Server Errors

Hola!

When we implemented the offline sync mechanism it occurred to us that the offline mechanism could be extended to a large number of situations and one of them is the situation where one can handle the server availability errors to a large extent.

Caldav Calendar code has been modified to allow for addition, modification and deletion of events during the case where a server is unavailable and a status message of 50x is received on the remote calendar request by lightning.

We assume that a human can't do anything about a server error, and we also assume that the server will be fixed. So this does not mean that the events u manipulate will sync remotely. They will however, sync, whenever the server comes back online.

you can find the binaries here and again these are purely for testing purposes and any bugs you can share with me via comments or mail me at: mohit.kanwal(AT)gmail.com

cheers
msk

First Step : Getting event information

About Events in Calendar

Events in calendar inherit from the calIItemBase interface and in order to store them in a cached file i wud need to set up some sort of parsing from an event object to a serializable string which I can then write to a file.

As luck would have it there is an icalString attribute in calItemBase which allows you to get the event string in ical Format. I can store this guy and use it to construct a calItemBase object which I can then write to the cloud when online.

Here are the preliminary results.

http://mxr.mozilla.org/comm-central/source/calendar/base/public/calIItemBase.idl#64

The Great Plan

The Plan currently looks like this

So yeah this is the plan so far, Fallen and Ludovic have asked me to try and extend calCachedCalendar.js if possible because it would allow the providers to use the sync() functions for free without having to implement their own versions. 

So this is how I am going to approach the problem

• Add a property in IChangeLog interface, which also for offline sync and also stores a ChangeLog file, the implementation would be provided by different providers, and it is to be seen if I can move this inside calCachedCalendar.js but it won't make sense.
• Modify isCalendarWritable to see if the calendar can be synced offline which basically queries for IChangeLog and gets the offline sync property
• Add implementation for storing the sync actions in a flat file, for the CalDAV provider
• and implement a replayChangesOn -> generalized version to handle the two way sync

This week I will try to get the above set up done for at least the delete item method, coz its the easiest so far.

After that the second part would deal with the sync mechanisms and making it truly smart and worth having in the mozilla lightning trunk :-)

I guess I can say that I am quite confident of my understanding of the code in calUtils and calCachedCalendar

cheers

msk

Building Thunderbird + Calendar

Today I spent my entire time working with the building thunderbird and calendar together. I think I cleaned it about 3 times before I decided to backup my changes and update the directory from the start, that means, full clean-up. Everything deleted.

One of the important things I think is to keep updating the code on a daily basis so that you do not fall too behind the working set because it is for all these changes that the local code base falls behind and causes merging troubles.

I still not quite get the version systems CVS, HG, GIT, and others used by people, because it facilitates integration of code faster but it comes with its own set of headaches. Essentially, some body works on some part of the code at a single time, but I guess the versioning systems have their own advantages, especially git.

Long Night ahead, :-)

cheers
msk

Hacking around the code

First sucess is always a sweet one. No matter after how long it comes.

I spent this week, trying to hack around the calendar code-base.

Instead of making changes to the actual code and then building the product again and again, I am instead editing the application extension directly, since lightning is in the form of an extension to thunderbird, this makes it easy to edit the extension code and test out the functionality real time without the need for a build. This however, means, the application restarts everytime.

Anyways off to making at least deletion part of the syncing process.

cherios
msk

Mozilla Bug Assigned

Finally, I am down with the real stuff to be done. I have been assigned the bug in Bugzilla making me responsible for fixing up of the offline enhancement feature. It also puts a lot of community checks and balances since a number of people have an interest in the bug and would be making sure the fixes i propose are of a high standard.

Look up the details of the bug here: https://bugzilla.mozilla.org/show_bug.cgi?id=380060

The First Click

Yay, I have been selected as a participant of the Google Summer of Code Programme 2011. I will be working with Mozilla Calendar Project in order to extend the functionality of its lightning extension, so that it can support offline synchronization of the stored calendars of a person. This blog is going to be the officially maintained status report of the project. I am very excited to be part of the Mozilla community because it has always inspired me to take up software development. Jamie Zawinsky was involved in the foundation of Mozilla and spear headed the tirade of open source software. He is an inspiration for me and I hope to put my very best in this project.

Here's my proposal on the GSoC Website. http://www.google-melange.com/gsoc/proposal/review/google/gsoc2011/mohitkanwal/1

My Project Homepage on the GSoC Website: http://www.google-melange.com/gsoc/project/google/gsoc2011/mohitkanwal/25001

Let's Get Started for the ride :-)

msk