How we came up with the idea about MeeTTY

Updated: Jan 08, 2021

Pandemic

Apr 2020, Its the start of COVID-19 pandemic 4, governments all around the world started lock-down, no one should roam around outside their houses. I’m one of the coordinator of ilugc.in 5 who conducts monthly meetings every 2 nd Saturday. Last month meet (Mar, 2020) was conducted physically at IIT 6. It is not possible to conduct this month meet physically. We have to go online.

Frustration

This month’s meet is due in next week, obviously we are going online this month like every other special interest groups around the world. But, we are yet to decide on how we are going to conduct the online meet. As our group only promotes Free and Open Source software 7, we cannot go with online meeting platforms like Zoom 8 or Google Meet 9 or some other commercial platforms. We have to stick with FOSS based solutions. These are the choices we considered at that time,

Jitsi 10

Just like most FOSS group around us, we would have went with Jitsi, but somehow we didn’t want to go with jitsi. It may be because we thought of installing Jitsi on our own server to improve video playback but ended up not choosing it because of the thought of buying/creating new instance in aws and doing the actual installation. At this time, we were looking for a solution which don’t involve anything to setup in a server.

Jami 11

Jami looked very interesting, its peer to peer and no server involved 1. But when we tried it in different OSes, the application crashed in OSX, Ubuntu LTS, it only somehow stable in Arch. Also functionalities are not consistent, and some functionalities didn’t work. So we decided not to use at this time.

Big Blue Button 12

At least for Jitsi, we can use it without doing any server setup through https://meet.jit.si/ , but for BBB, we have to setup server. Also, it doesn’t support latest distros 13. So, BBB is out of our choice.

Matrix.org 14

Matrix can do video conferencing using jitsi bridge. Again, this also involved setting up a server with jitsi and matrix and connecting each other. So, we didn’t choose Matrix.

All the platforms we considered are proper audio/video based conference solutions. They need proper servers with enough bandwidth to operate in a useful way. We lacked a server and not ready to invest.

The Trigger

We were all discussing and evaluating the platforms at #ilugc 15 2 channel in Freenode 16. At that time, shrini 17 asked this question,

“Why do we need full audio/video platforms, why can’t we just use IRC and terminals?”

—shrini

We started reasoning this question, like what we loose if we go with IRC based communication instead of live video conference. We already know that IRC works for communication, its text based and doesn’t suck bandwidth. The meetings we conduct are mostly like someone will talk about a technical topic which involves showing terminal commands and explain about what those commands do to achieve specific goals (like setting up nginx 19 etc.,) so IRC is enough to convey the message to audiance.

Now, as I previously said, most of our ilugc talks involves showing commands and explaining what they do. For the explanation part, we already arrived at the conclusion that IRC is enough. Now, we need to find a way for presenter to share terminal to the outside word.

The Idea

This is where things got interested, I already know that there are ways to show terminal output in a webpage 3. I also know that python can do pty 21, means, it can create a terminal, run a program on that created terminal and handle input/output of that created terminal which in turn will handle input/output to that program.

So I thought why not just combine python’s pty with whatever solution 20 exists to show terminal output in web?

I come up with this concept,

  • run a server to serve a webpage

  • the webpage should contain two parts which uses xterm.js 20 to show terminal output

  • the first part should show the terminal of presenter, it should be read-only, whatever the presenter do in the server should be displayed in this presenter’s terminal.

  • the second part should show another terminal to practice what the presenter is explaining. This terminal should also be capable of getting input from user

I quickly started prototyping my idea, I used the below tools

flask 22, flask-socketio 23 and socket.io 24

Flask is used to serve webpage, flask-socketio is used to handle inputs from xterm.js 20, whenever a new page get served, socket.io will immediately initiate two websocket back to server, flask-socketio will handle those connection, one websocket is for presenter's terminal called tmux and another websocket is for practice terminal called nspawn.

Whenever tmux websocket connection comes in, flask-socketio will create a new pty and will start tmuxcmdline defined in the environment. The input and output of that commandline will be sent back and forth through tmux websocket so that it will appear in the presenter's terminal part of the webpage

Whenever nspawn websocket connection comes in, flask-socketio will create a new pty and will start nspawncmdline defined in the environment. The input and output will be handled through nspawn websocket so that it will appear in practice terminal part of the webpage

tmux 25

tmux is a fantastic screen multiplexer. It uses client-server model, for our purpose we basically start tmux client through tmuxcmdline to wait and connect to a particular tmux session called broadcast in read-only mode. So all the presenter's terminal created through MeeTTY’s webpage will be read-only clients to a broadcast tmux session.

If we want to show something to the audiance, all we need is to connect to the same broadcast tmux session as read-write client and start typing, everything we type will be replicated automatically to all the read-only clients which are connected to the same broadcast tmux session. Thus, we achieve the goal of broadcasting presenter’s terminal to multiple audiance.

linux usernamespace 26

Opening a terminal in a webpage and expose it to the whole world is the stupidest craziest idea. But, the thought of providing a place for audiance to practice what the presenter is teaching is very interesting. So, instead of starting a direct shell, we utilize linux usernamespace container to start a shell through nspawncmdline and attach it to practice terminal through nspawn websocket. Thus, practice terminal will have a restricted shell which audiance can execute commands.

kiwiirc 27

I completed my prototype and showed it to people in #ilugc, People provided great feedback, shrini come up with the idea to include a web IRC client called kiwiirc so that people can use a single web page to login into #ilugc channel, see what the presenter is teaching through commands and practice those commands. mbuf 18 suggested to have single page and show all three parts of the webpage (IRC window, Presenter's Terminal and Practice Terminal) in a single page instead of having three tabs to switch between them. He also suggested to put Powered By label somewhere in the webpage. I didn’t realize the significance of putting that label, but after sometime I understood how important that label is, The word Attribution in Open Source licenses refers to this label.

So, this is how we establish two terminals and an IRC client in MeeTTY’s webpage.

In the mean time, April month meet took place through #ilugc channel. But we didn’t introduce MeeTTY to ILUGC monthly meet participants. At this point, you may think that we almost reached our goals, but this is just a start.


To be continued..


tmuxcmdline

This environment variable contains the commandline which gets executed whenever there is new tmux websocket establishes. This will connect to the broadcast tmux session as read-only client.

nspawncmdline

This environment variable contains the commandline which gets executed whenever there is new nspawn websocket establishes. This will start new shell under linux usernamespace.


1

actually TURN is needed, but its another story

2

we reactivated and acquired admin rights to this channel after the start of the pandemic when we noticed that #ilugc channel was abandoned long before

3

I don’t know exactly how to do it 20, at this time, but learnt later.


4

https://en.wikipedia.org/wiki/Coronavirus_disease_2019

5

https://ilugc.in

6

https://www.iitm.ac.in

7

https://en.wikipedia.org/wiki/Free_and_open-source_software

8

https://zoom.us

9

https://meet.google.com

10

https://jitsi.org

11

https://jami.net

12

https://bigbluebutton.org/

13

https://github.com/bigbluebutton/bbb-install/issues/37

14

https://matrix.org

15

https://meet.ilugc.in

16

https://freenode.net

17

https://goinggnu.wordpress.com

18

http://shakthimaan.com/

19

https://nginx.org

20(1,2,3,4)

https://xtermjs.org

21

https://docs.python.org/3/library/pty.html

22

https://flask.palletsprojects.com/en/1.1.x/

23

https://flask-socketio.readthedocs.io/en/latest/

24

https://socket.io/

25

https://github.com/tmux/tmux/wiki

26

https://man7.org/linux/man-pages/man7/user_namespaces.7.html

27

https://kiwiirc.com/