Karma/Collaboration
From Sugar Labs
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Objective
To provide a mechanism to enable collaboration using JavaScript. On this way, we'll be able to support collaboration on Karma lessons.
Use cases
Examples:
- A simple chat (over an html file), where you can see connected children to the activity and talk each other.
- Let's imagine a lesson: "Learning basic arithmetic", on this lesson we touch the topics: add, rest and multiply a number. At the end of the lesson we got the "Test". Here on "Test" one child writes a basic equation and challenges other child to solve it, then switch turns.
The problem
How to create an easy way to write collaborative JavaScript to be run client-side in browsers.
Keep in mind
- JavaScript has no model for distributed collaboration.
- Shared data can be considered volatile.
Possible solutions
It would be ideally as simple as possible and as web-like as possible.
lucian has suggested 2 possible ways[1]:
- Starting local servers in each Browse and using XMLHttpRequest(XHR) to send data between.
- Adding an API for this in window.sugar and using the existing Sugar collaboration Python API as a backend.
bemasc
- a DNS server and httpd server on each client. (example WikiBrowse )
m_stone:
- name the people with one wishes to collaborate with using:
- Telepathy
- DNS
- D-Bus to telepathy
- a way to get those names to the JS.
- D-Bus to telepathy
- HTTP to a webserver to D-Bus to telepathy
- data transfer via:
- D-Bus + Telepathy
- a central relay webserver
- point-to-point HTTP links to peer webservers.
Collaboration data:
Bemasc has suggested to store the messages using files and directories
- /users could be a list of current users
- /$USERNAME/ could be a list of messages, displayed as files
- To check for new messages, just poll the contents of /$USERNAME/.
- To check for new users, just poll /users.
- If you want to see what messages $USERNAME has emitted, poll /$USERNAME/
Also one other way is using http PUT & GET
Flaws: it's all broadcast, and it's all polling.
Broadcast is inefficient in the network if you really only want to send a message to a single user. Polling wastes CPU, battery, and possibly network.
On way to handle polling is setting a high timeout for XHR. (Thanks Lucian)
