Live data from Hacker News

Show HN: A virtual whiteboard for working or teaching remotely

whiteboardfox.com

1–10 of 143 posts

Re: Show HN: A virtual whiteboard for working or teaching remotely

#2
This is little 'scratch-your-own-itch' project I started working on about 9 months ago. Front end is GWT, back end is Java servlets. Database was originally MySQL but switched to Prevayler for performance reasons.

My YouTube video gives a nice overview of the benefits of a virtual whiteboard: http://youtu.be/MDEHFHG1l3Y

What does Hacker News think?

Re: Show HN: A virtual whiteboard for working or teaching remotely

#7
post #2

This is little 'scratch-your-own-itch' project I started working on about 9 months ago. Front end is GWT, back end is Java servlets. Database was originally MySQL but switched to Prevayler for performance reasons. My YouTube video gives a nice overview of the benefits of a virtual whiteboard: http://youtu.be/MDEHFHG1l3Y What does Hacker News think?

Nicely done, website is nice and it's great that you can just click and get started straight away. In your comment you said you moved away from mySQL, what exactly do you store in the DB? Which leads to the question: how do you transfer the drawing data between clients? I guess it's not a case of uploading a Canvas as an image?

Re: Show HN: A virtual whiteboard for working or teaching remotely

#8
Very nice!

My friend's parent is disabled and we thought about doing something like this and hooking it up to a touch-screen monitor for them.

That way the parent can see messages from her kids (in a different city) and vice versa without any effort or typing.

Re: Show HN: A virtual whiteboard for working or teaching remotely

#10
post #2

This is little 'scratch-your-own-itch' project I started working on about 9 months ago. Front end is GWT, back end is Java servlets. Database was originally MySQL but switched to Prevayler for performance reasons. My YouTube video gives a nice overview of the benefits of a virtual whiteboard: http://youtu.be/MDEHFHG1l3Y What does Hacker News think?

Nicely done, website is nice and it's great that you can just click and get started straight away. In your comment you said you moved away from mySQL, what exactly do you store in the DB? Which leads to the question: how do you transfer the drawing data between clients? I guess it's not a case of uploading a Canvas as an image?

The drawing is basically a list of strokes, and a stroke is a list of points - that is, (x, y) coordinates. So the database is mostly a huge table of (x,y) coordinates.

Uploading the entire canvas would far too inefficient - I simply upload the points.

The transfer between two clients uses a technique called 'long polling'. That is, the client sends an HTTP request to the server, and the server doesn't respond until it has received a message (ie. stroke) from another client.

Post reply on HN