New Headers : Schedule-Tag

Schedule-Tag is a new response header defined in RFC 6638 which is somewhat similar to ETag property of resources. The rationa behind the Schedule-Tag, is handing over the responsibility of merging changed object resource properties to the server.
With the current implementation, after every scheduling operation of invited calendar user, (Attendee changes the PARTSTAT value) causes to change the state of the object resource, which simply changes the ETag value and cause to occur inconsequential changes in the calendar user’s data due to some operations which possibly not affects to his/her PARTSTAT value.
Unlike the ETag value, Schedule-Tag only changed after the organizer made a change to the object resource .
Once a client tries a PUT request on an object resource, s/he should specify the last known Schedule-Tag of the object which is being asked with if-schedule-tag-match header which will be implemented in later stages. In case that the object resource has been modified with inconsequential changes, they have to be merged to the attendee object resource within the server and the new value has to be updated. Otherwise server must send a 412 (pre condition violated) status code in the response header.
Bug for the feature is here.
Changes of schedule-tag property in different situations.
I noticed that SOGo server, which I have used to work on has not yet support the schedule-tag property as it doesn’t return a value for schedule-tag value in the request header. Therefore, all current testing is being done with Google calendar.

Mozmill test for IMIP bar

There was a change in the planned routine in last week.  Mohit and I decided to poke into mozmill testing of IMIP bar though it was scheduled to latter stages of the project.

Bug for the test is here.

I had to look into mozmill automated testing API in order to write the test. Mozmill contains with some modules shared between firefox,  thunderbird and specific util modules for lightning. Mozmill thunderbird helper classes provide access to control utilities in thunderbird  while calendar utility classes provide ability to manage with events.

The automated test needed to inject a mail containing an invitation to check whether the IMIP bar is loaded and buttons are displayed. Then accept the event and make sure it is added at the correct location in the calendar view.

Source for the test is here.

In order to attach the invitation (invite.ics) to the email, I had to use thunderbird’s attchment-helpers module along with some other modules from tb as well.

There were few hard cases. First imip bar didn’t showed up and the attachment was showed up in the body. Once going through related RFCs, could find that, it was a some theoretical matter of adding the attachment header as defined in RFC.

Again, it was automatically clicking on “Don’t send email notifications” in the Email notification sending dialog box which appears once it’s clicked on the accept invitation button. gMockPromptService module was pretty much helpful for that. gMockPromptService creates the dialog virtually and returns the value (we can change the return value) to the caller regardless of the context of the caller.

In debugging I found that test functions are not executed unless the function name isn’t starting with the prefix “test”. That was pretty much helpful for debugging.




Deepening in the code

spent last few days exploring the code base and setting up the environment to debug Thunderbird.  Used sogo server to configure the CalDav. As I have installed a 32bit version of ubuntu, had to switch on Intel’s virtuaization feature in order to use sogo’s 64bit zeg image.

A summary on some frequent files would have been a little useful.


This contains utility methods to be used in Lightning operations. ie: cal.LOG(); for logging messages in the error console.  This is loaded in many of the source codes.


Most of the operations related to itip is contained in this file. i.e: determining the latest resource of a event file by examining the sequence number and the datetime stamp.


This contains function implementations for provider services. ie: SendHttprequest to send the queried XML message to the server.


contains all the methods to send the initiate the PROPFIND request to the server to, deleting a calendar resource object from the remote calendar. ie:

Sending the initial PROPFIND request to find  the remote calendar.

sending a PROPFIND request with a “allprop” element is described here.

Initial PROPFIND request:

[xml]<D:propfind xmlns:D=”DAV:” xmlns: CS=”” xmlns:C=”urn:ietf:params:xml:ns:caldav”>

Response from the server:

 <?xml version=”1.0″ encoding=”utf-8″?>
<D:multistatus xmlns:a=”urn:ietf:params:xml:ns:caldav” xmlns:b=”” xmlns:D=”DAV:”>
<D:status>HTTP/1.1 200 OK</D:status>
<D:collection/><calendar xmlns=”urn:ietf:params:xml:ns:caldav”/>
<vevent-collection xmlns=””/>
<vtodo-collection xmlns=””/>
<schedule-outbox xmlns=”urn:ietf:params:xml:ns:caldav”/>
<D:owner xmlns:D=”DAV:”>
<D:current-user-principal xmlns:D=”DAV:”>
<D:supported-report-set xmlns:n2=”urn:inverse:params:xml:ns:inverse-dav” xmlns:n3=”urn:ietf:params:xml:ns:carddav”           xmlns:D=”DAV:” xmlns:n1=”urn:ietf:params:xml:ns:caldav”>
<n1:supported-calendar-component-set xmlns:n1=”urn:ietf:params:xml:ns:caldav” xmlns:D=”DAV:”>
<n1:comp name=”VEVENT”/>
<n1:comp name=”VTODO”/>

I’m trying to send a HTTPrequest to get a property by name. It is done by the “propname” element.

my request:

<D:propfind xmlns:D=”DAV:” xmlns: CS=”” xmlns:C=”urn:ietf:params:xml:ns:caldav”>

As long as the property name is not mentioned, it will be considered as “allprop” request.

As the next step I hope to jump into the implementation of schedule-calendar-transp property.

Entry Points

Automatic scheduling of calendar collections was introduced by CalDav extension which was a protocol built upon WebDav. (There is CardDav protocol introduced parallel to CalDav for transferring of vcard information) CalDav was introduced by the IETF from RFC 6638 but Lightning’s implementation was done before the final version was introduced. Referring to the draft version 4.

I went through both versions to identify changes between them and a list was prepared. I explored the bugzilla and the calendar blog to find bugs related to CalDav properties and  found some of them that can be used to track the implementation.

I started with the bug used to implement the CalDav in Lightning.

Also, hope I will be working the code around this bug to implement proposed schedule-default-calendar-URL Dav property in Lightning.

My next step is to setup the Sogo server for testing features. It seems to be a very much updated and well aligned with the RFC 6638.

Also, I will be using next few days to hack into the code base to get a better understanding about the implementation along with RFCs. New bugs for each feature in the proposal are planned to be posted in the Bugzilla to get feedback and guidance from the community.


Update Lightning Invitations to Latest Specification

My name is Malintha Fernando and I am a student developer from Sri Lanka, currently studying at University of Moratuwa. I started contributing to Mozilla some months back (Still got a lot to learn) as my first contribution in open source and glad to be a part of the Lightning project in GSoC 2014. :)

The objective of this project is to improve Lightning’s scheduling system by updating the available features to the latest RFC specifications. As we know most of the Lightning’s implementation were done referring to the draft version 4 of the RFC 6638, there are some features lagging behind from the final RFC document.

This is a diff of two versions.

This is a summary of changes identified so far which are planned to be implemented.

All comments are mostly welcome.

I hope to post all GSoC updates at my personal blog, me-levense once or twice a week.

Got selected to GSoC 2014


Every Computer Science undergraduate who might have heard about GSoC would not merely be satisfied of hearing it. Definitely, there will be some tries to participate in it. It is not a plenty of undergraduates’ dream to getting selected to Google Sumer of Code, certainly there is a lot more than a plenty.

In University of Moratuwa, where I study, GSoC is not just another event in the world of Computer Science students. It has become a part of their culture. Creating participants in GSoC in massive numbers is just-another practice of the university activities. All the related field students (students from department of computer science and the faculty of Information Technology) work hard to get selected in this prestigious event in the world open source calender.  University staff, past GSoCers and Google Student Ambassadors encourage undergraduates to apply for the event expecting not the  stipend but targeting  on the massive reputation that a student can gain from it.

Why UoM is special at GSoC?

UoM is holding the record for participating most number of students for the competitive event for impressive 7 consecutive years with 265 participants for all previous 9 years since the inception!


These numbers were steadily increasing over all past years even during the war era. Even Chris DiBona, Director of Social Impact and Open Source at Google mentioned his excitement over these numbers during his speech at his “Decade of Google Summer Code” speech at University of Moratuwa.

How did I motivate?

It is said that “Eighty percent of the success is showing up”. It wasn’t false that much if you once look at a GSoCer’s ability to show up. They are pretty good at what they are showing up. They are mastered of the field and always got highlighted in the industry as well as in the university.

In the very first year of the Uni life, i could attend to a small meet-up of past GSoCers and newbies. They were from Fedora project and encouraged us to apply to Fedora project in the GSoC 2012.

I was like… “What the hell is Fedora?” and “What is the relationship between Fedora and Google?”

I looked into some documentation of fedora and projects in the GSoC. I would be lying if I said I could understand a single project in the list.

Well… Time passed, promoted to the level two in the faculty. Again, looked in to the projects list. Unfortunately, it was the exam season and couldn’t allocate time to understand optional worse, neglecting the necessary worst.

At the time I moved to level 3, I was somewhat matured about the scopes of projects and the amount of contribution I had to made to yield some results.

Selecting Mozilla


My answer for the question “Why Mozilla ?” in the proposal template form.

There are several reasons behind selecting Mozilla. I was using Firefox and loved its designs ever since I got hands to a computer. Another reason was my desire to commit for a project that would cause cheer of a lot of users. Contributing for a project in Mozilla that actually used by millions of people all around the world, causes a feeling of satisfaction by knowing that there can be someone making use of some code snippets I wrote. I always enjoy volunteering. Satisfaction becomes bigger, when the project becomes bigger. Finally, I would happy to repute my GSoC participation with a big brand name in the internet like “Mozilla”.

Start Contribution

Mozilla was one of the most forefront open source projects in the world. It has thousands of contributers, contributing to various technologies and perspectives.

Designers,  Coders in tens of projects, bug reporters, bloggers contribute to the progress of  Mozilla. I would say that, at the first time I visited to this website, I was amazed. My question was, “Do they have a site for this thing too?”

It has provided you a lot of alternatives to match with your preferences. Mine was JavaScript and Calendar!

Once I got my choice……….

Okay, here is the tricky part…

Once I got my choice, I moved to the melange site! Not to the Mozilla developer network! I wanted to see that was my selection correct. I wanted to make sure that is there a possibility to have another GSoC project from this project. I went through project list of 2-3 years. yes there was. So I was correct! There was several projects in last years and seemed a possibility was there. (Of course, you can suggest a project by looking at the codebase or the Bugzilla – the bug tracking system of the Mozilla, but notice I was a newbie to the giant project)

thunderbird_logo-wordmark_RGB-300dpiI went through Thunderbird’s documentations and Bugzilla to find out available bugs. I found a nice documentation describing where to start and how to find out new bugs and get then assigned.

Have to say that, Mozilla has the best stored knowledge in world of open source I found so far. There developer network, provides you solution for any sort of related technical matters.

After going through a lot of documentations (and a lot of them) I though to focus on the Thunderbird’s calendar extension, Lightning project.


-This article is getting longer with my excitement grows- have to make this short –

I had to search for easier bugs in bugzilla, and a get one of them assigned to myself. Certainly, I didn’t have authority to get a bug assigned to myself. I had to comment in the section asking from someone to assign the bug to me. Once you get a “New start bug” to work on, you can contact the mentor assigned to the bug to get any doubts clarified.

After I got some experience with the codebase I turned to the GSoC. Went through the project statement, contacted the mentor for clarifications and glad to say that they were really responsive! Sometimes, they may take some 24s of hours to reply, but always give them arounf 48 hrs to reply for a mail. They also have their own works other than volunteering. :)

It’s done…

Preparations and orientations were finished. Now this is the time for discovering the exact meaning of “Coding”.

Hope, I will be able to achieve my goals and contribute to the Internet giant in my capacity to make open source more productive and Internet a better place.