Hello everyone.
Is everyone hearing me correctly?
Yeah?
Great.
My name is Jounia Malka.
I am a PhD student at Telecom Paris and I'm doing software supply chain security.
I'm also an XOS developer but what I'm going to talk to you about today has nothing to do with this.
I'm going to talk about a weekend project I did that is called LINCO and about like deficiencies I see in the public calendar's ecosystem.
I'm running with a pretty adversarial screen resolution so if at some point the slides are completely broken I will try to describe what you're supposed to see.
Right.
So what I'm going to talk to you about today is like what I think is problematic in the public calendar and the calendar ecosystem for collaboration.
And I'll explain a motivational situation that made me do this weekend project and then I explain like the two software we came up with to solve this situation.
Right.
So I think public calendars are sometimes or calendars in general sometimes a bit painful to interact with.
And the problem I saw when I started thinking about this is like when you have like a public calendar and you want to follow this calendar on your calendar clients.
There's different things that your calendar client can do.
Let's say you want to.
It can maybe have the capacity to import some ICS files.
So even files in bulk but then it will not do anything more with this ICS file than display display them to you and will not for example subscribe to like the updates of these events and will not like.
Continue to fetch new events as they come forward.
There is like the intermediate player that will fetch the updates.
So if you're even get updated like change location or something like that some some calendar clients will update them.
And some will be the next player that do everything that you want is basically fetch new events as they come into your calendar.
The other problem that I think is is is big like is that calendar providers are not always nice with with the possibility to export your calendars as public calendars that other can follow.
Sometimes it's make it very complicated to find the actual option to export these public calendars and make it complicated for people using other calendar software or providers to to actually subscribe to your calendars.
And I think also the calendar ecosystem is lacking some nice to have features that would make life easier.
So I think like public calendars are not easily composable.
It's not easy to like take a few public calendars and merge them into one one collection of calendars which is a nice thing that you can want to do when you're for example you're like you want to follow all events in about for example let's say in XOS because I'm an XOS developer in your region and you have several entities that organize these these events.
And they all have a calendar and what you would like to do is maybe do some creation of these calendars and propose a collection of calendars that other XOS users might want to follow to get all the events in one place.
This is not easily done.
And the other thing that I think would be really nice is filtering of events in calendars.
So just like you you are able easily to do filtering of emails.
Why not be able to to filter from calendars you follow events that are relevant to you.
For example events happening in certain certain geographic area or at certain given date or hour that could be really nice.
And this is also very complicated to do I think.
So all this thinking came from like a concrete situation where at my school there is a lot of different association that all organize their own stuff and they all maintain some play some kind of of place where they put all the events that they organize.
Sometimes it's a calendar.
Sometimes it's just a plain web page that you cannot do much with.
Sometimes it's just send emails.
But there is no there were no central place where you could just see all that get organized on the campus and be informed that way.
So we had like a first iteration of solution for for this.
This problem the first software that got developed at my in house developed at my school was called Mitis Mitis is a is just a web web service where there is some kind of interface.
I don't know if you see it correctly but it's just an interface where it shows all the events from all the calendars.
And but it's it's really nice and it was a first step in the right direction.
But what you can do is this interface you can ask it to export ICS file so you can import all these events into your calendar clients.
But what you can do is ask it to act as a calda server and add it to your calendar client and have on your phone or your computer all the events getting updated in real time and basically be able to follow all these events from all this
this situation without action on your part.
So what when I saw that I was like I kind of want this to be a calda server.
So I created Lincoln so Lincoln is a is a weekend project and it does exactly that.
It takes this idea and implement it as a calda server.
So the design goals when I try to to think about Lincoln is like I wanted to basically do a calda server that will display several calendars coming from different places into one collection.
So for the client it looks like it's one your collection of calendars that you're importing but actually all these calendars are hosted on different places.
The other design goal that I want I wanted is like to be able to do some processing locally that Lincoln be able to process in a way or another the events so that we can have at some point maybe like the filtering features that I was talking to you about.
Okay so the first iteration of this when I was thinking and trying to implement this my first iteration of my first idea was like okay I'm going to implement this in rest because why not.
And actually I wanted to learn rest at the time.
And I'm going to is going to be simple I'm going to use some rest libraries that act as calda plans so we have like mini calda for kitchen fridge.
And these libraries are going to to perform the request to the underlying calendars and and this this part is kind of like logical and easy but the problem is that you also have to implement all the web dev calda specification on the other side.
So you have to implement the HTTP server that's implements all the end point and all the specification of the web dev calda specification and and then you have to get all the calls and rewrite them in terms of function calls of these libraries.
So the problem here was like it's kind of like a bit too painful to do because the calda web dev specification is very big and a bit.
Complicated and it was a lot of things to do just for a weekend project so I was like this is no this is too complicated to painful there has to be something else.
The second iteration.
I was like this time I want to implement as little as possible.
Of the of the web dev calda specification and and still get something working.
And the idea is like we are going to rely on on the the clients so the calda clients they know how to do to format correctly the request.
And the calda servers the underlying servers that we are trying to aggregate they also know how to answer this request so basically some somebody did the jobs the job for me and what I need to do is only like forward the appropriate request and appropriate body.
To to this underlying calendars get the answer and maybe do some some some kind of modification at some point of the in the answers but we try to keep it as a minimum so what we see is we have the client client collect connect to link call.
And then link call for what the request to the underlying calendars and the the answers come back and then we forward back the answer to the clients so we get we kind of act as a proxy and at this point some processing can happen of the request some filtering and some minimal modification needs to be done.
Okay so if we if we start to to go in into the depth of the subject.
We have two kind of request that we need to handle.
So the first part the first kind is like request that the client is going to send us to discover the calendars that are inside the collection and these we kind of to this is the part we have to implement ourselves.
Because we cannot forward this this request to to the underlying calendars it would make no sense.
And the second part the second type of request is the one that wants to client as acquired all the as a list of all the calendars that are in the in the collection that we are trying to to give it to him.
Then it can query the individual calendars and this we can completely just forward the request to the underlying calendars and practically do nothing on them like.
Okay so I try to give you an insight on how this this can work.
We have like in a in a calda client what you do is you connect to the you write down the the URL of the server and the username and password and it will try to to query the webdav server to to ask what is the calendar home.
For this for this user for this principle and so we implement one one endpoint that is called principles link all so link all is the name of the user you should provide to your.
Calda clients and and then it will try to to query this pass and.
And what what kind of clients are going to send this is called like prop fine request it's property find request and it will ask for this specific property calendar on set it will ask for.
A lot of different properties that we don't really care about but at some point it will ask for this property and when it does we answer that it should go and look at this pass slash cal.
And so when it behaves correctly this is what it does.
So the next column the calda clients do they they go to this past because they now they know this is the collection route.
For for calendars and will try to to now find out what are the calendars that are in this collection.
So it queries this this pass and then at this point I tried to implement also this.
This pass by try to like guess what properties we should send back to the to the client at this point.
But it was too also to painful so I took another direction.
Instead I forward all the I forward the request that the client send me to all the underlying calendar and the also an answer and I aggregate the answer and this is what I send back to the client so now the client know the.
Basically all the calendars that are in this in this collection.
And we have to do some kind of hijacking of the answer.
So that we modify some of the fields and the most important field so there is a lot of cosmetic fields that you can modify but the most important field that we need to modify is like the URL of each calendar so basically.
Each underlying server here when the answer to the request they will say oh fine this calendar this specific calendar at this specific URL which is they will give their URL right so we have to change this so that it corresponds to what where we can answer the.
The request for the specific calendar so we we change the URL for each calendar to slash calc slash the name of the calendar and so now the calc clients as a list of URL for each specific calendar.
And it will query this URLs to fetch the events.
And so now this is the part where we just shamelessly just forward this this request to the underlying servers acting as a man in the middle.
And again when the response come then we can.
Do some little modification and we can do some cosmetic modification like change the color of the calendar as it should appear on your on your client so.
It may be possible that you try to aggregate several calendars that have the same color so you want to do some modification at in the in the.
In Lincoln so that when they appear the collection appears on the clients they all have different colors or nice colors.
So as a little working example.
Sorry.
Let's say I'm like I want to offer Nick's US calendar to the user that aggregates several several different.
Calendars that are offered by different entities and I have like three entities so for example the genome which is like an association that can offer Nick's US meetups.
Let's say a school can offer Nick's US courses and there is some next parties which are like let's say very real things organized by Nick's people.
And that is also in this third third calendar and so here I have three different calendars in three different.
Hostors.
And so the way it works is like I have to create like a JSON file that.
Basically states which are the calendars I want to integrate in my in my aggregated collection so I just list them like so.
Then I just run Lincoln with this specific calendar that JSON file.
And it gives me a Lincoln server so basically if you want to try at some point during the day and tell me that it doesn't work on your specific client.
Oh it doesn't that it does work I don't know there is the server is currently live.
But what you get if you are using.
Mac OS or iOS like I was when I worked on this this project is.
You had the Caldav collection and you just specify the URL that I gave you and the user link.
And what it gives you is one calendar one collection that has three calendars these three calendars.
And that will display basically the events that are in these calendars.
And whenever like the underlying entities add new event to these calendars it will update and be.
Be available in your client directly.
She's also working on Thunderbird and I don't really know about other clients.
And now let's let's talk about what I would like to do in the future.
So as I told you one of the goals of this project is.
Is to also have some some kind of filtering feature where you can say I'm only interested in events happening in let's say this city or happening on Tuesday night or whatever.
And currently the way Lincoln is implemented is that you can do that you could go in the rest code base and implement the filters yourself.
Which is.
Admittedly what not a great user experience so what I think I want to do if if I ever get some time.
Is kind of device like a domain specific language where you can write some filtering expressions.
And for your calendar so you can you could say you would have the expressivity to express basically the kind of the kind of filter or rules that I just told you about.
And then you would way on there like upload this expression to Lincoln.
And it would it would do the filtering before the events comes to your calendar client.
The other thing that I want to improve is that like Lincoln is currently only able to to serve one calendar collection.
And one improvement that I would like to do is have it be multi multi tenancy so it could host as many calendar collection as needed.
And and have like some kind of web interface where you could upload this this expression in this domain specific language to define this new calendar collection.
And the last thing I want to say is that I think maybe this kind of filtering idea could be also in the future accepted in by KELDA servers and so maybe entering in some standardization.
Thank you for your attention.
Lincoln is available on GitHub at this year.
And.
If you have any question I would go to answer them.
Yes.
Hello.
Hello.
Hello.
Hello.
First is someone who has dealt with a lot of counter hell.
I appreciate the effort you're putting into this project.
And my second question my question is.
Is there any sort of right functionality for give me you cover this early.
But if you're just passing things in proxying them.
If you have the appropriate credentials can you not like could you add events to these collective calendars or is it a sort of read only set up.
You mean can Lincoln add events.
Can you add can you add events through link how or can you could do that.
Yes.
There is no limitation that you but what kind of events would you I mean.
What's the use case like you're managing the collection and you want one more event to appear to the people that are following this collection.
Yeah.
Or maybe the people who are subscribing to you know people who are receiving these events say hey I want to have an unofficial after party.
I'm adding it after this main event.
Other people can see it.
So the immediate answer I can give to this is if you really as a collection manager want to add some events you could add your own calendar that you manage and add the calendars.
The event to this underlying calendars and it will just work.
There is no really there is no real limitation that you couldn't do it directly in Lincoln.
But I think like in terms of user experience there is no real interface where you could do this easily.
OK. Thank you.
Thank you for the talk.
Have you considered aggregating from social media like Facebook or similar.
Sorry I didn't hear very well.
Oh sorry.
Have you considered aggregating from social media like Facebook or similar.
Would this also work.
I have not considered this yet.
I know that I mean this could totally be an option.
This is Lincoln is currently a very rough prototype.
And what I want to do is add some some other ways to integrate events that are not directly from CalDaf servers.
Mostly like the priority is adding events from Unpoint that just serves ICS files which is like I know some some people ask for this.
But then adding some events from sources that aggregate some events like social media is also interesting and I will consider that.
Other questions.
OK. Thank you.