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Comment by bluetidepro | Hacker News Reader

The first thing that I loved about this, that drives me crazy on other real-time online editors, is that pressing "tab" actually creates a tabbed space, and doesn't change the active textarea. Nice job!

Any plan on open sourcing the code to do the real-time editing? I would love to use this real-time editing concept in a project I'm working on.

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Thanks! It was actually really simple to make with two tools: http://ace.ajax.org and http://www.firebase.com

If you want to chat about building it I'd love to give you any tips - i'm nbashaw@gmail.com

How did you accomplish the real-time text editing? Is there any OT engine that you hacked into Firebase?

Basically on keyup I ship the whole contents of the editor and the cursor position to firebase. I'm also keeping track of all the active connections to a scratchpad document so I know who is typing. Anytime the code changes on the server, it triggers a callback function on each client that will update the contents of the textarea. If someone else is typing, the document is locked so only 1 person can type at a time. This way I can avoid all the potential merge conflicting type things that can happen.

I'm not sure what an OT engine is. What is that?

OT (See: http://en.wikipedia.org/wiki/Operational_transformation) is one of the technology solutions to the problem that you've solved through a locking mechanism.

Not sure what server architecture you're using, but in Node.js there is a pretty amazing package that integrates with ACE called ShareJS (http://sharejs.org/).

Have you experimented with synchronizing cursors at all?

Thanks! I'll have to read up on OT. Our backend is totally hosted by Firebase, other than a simple Sinatra app that generates the unique IDs.

When you say synchronizing cursors, do you mean having multiple cursors (google docs style) or having a single cursor be in the same position for all clients? We are doing the latter, and I wasn't aware it was possible to do the former with ace but I would love to do it if I can

Do you know what/how Firebase is doing the realtime updates? Websockets with fallback to flash?

I believe that's it but I'm not sure. I've emailed the firebase founder and he might be able to chime in here

Hi, I'm one of the Firebase engineers working on keeping clients connected.

We use a mix of different methods to maintain a connection. We normally start with our custom long polling implementation and move to websockets when they are available. We do not currently make use of any flash sockets.

Is Firebase open source?

It states so on the sites/GH pages, but could not find pointers to repo [after 2 circle through 5 different pages poiting to each other].

Seems that I can't reply to the child of my sibling comment so I'm replying here.

ACE is quite ridiculously powerful. On its primary implementation (http://c9.io), it supports multiple cursors with concurrent editing.

I've been able to use ShareJS to get concurrent editing working (see: http://plnkr.co/edit/?p=preview&s=HN4933608) but haven't had a chance to display visual cursors for all simultaneous users. I was thinking that I could get that working using Firebase.

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