Karma/Collaboration

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)