Hi there,

I got some requests to re-record the tutorial talk I gave at DevCore 2015,
"How to build a timestamping smart contracts app in 30 minutes". It's now
available here:

    https://bitcoinj.github.io/document-timestamp-app

It covers:

   - How to customise the wallet-template app for this use case
   - How to construct a complex multi-stage SPV proof of block chain
   inclusion
   - How to save and then verify proof files
   - How to bind transaction confidence state to the user interface
   - How to create a Mac DMG bundle with a custom icon

I hope someone finds it enjoyable!



On Thu, Apr 9, 2015 at 10:23 PM, Mike Hearn <mike@plan99.net> wrote:

> Next week on April 15th Gavin, Wladimir, Corey and myself will be at
> DevCore London:
>
>    https://everyeventgives.com/event/devcore-london
>
> If you're in town why not come along?
>
> It's often the case that conferences can be just talking shops, without
> much meat for real developers. So in the afternoon I'll be doing two things:
>
>    1. Running a hackathon/workshop type event. The theme is contracts,
>    but we can hack on whatever you all feel like.
>
>    2. My "talk" will actually be a live coding event. Writing contracts
>    apps has become a lot easier in the past few years, and to prove it to you
>    I will write a decentralised cross-platform Tor supporting document
>    timestamping app that uses OP_RETURN outputs and has a nice GUI ..... in 30
>    minutes, on stage.
>
>    Don't think it can be done? Turn up and see for yourself.
>
> See you there!
>