As far as I'm aware of, the blockchain only gets signed every few minutes or so.
So how can you achieve this low latency? Do you just base your decision "x has paid" on the still unsigned chain? That's quite risky and open for exploits, isn't it?
Also, what do you do if there are orphan blocks in the chain?
(Comment about coindl.com, not the book the article links to.)
New blocks are created in a lottery process (mining) that could take seconds to hours for someone to win. We are using unconfirmed transactions but are willing to take some risk while developing strategies to mitigate that risk. Orphan blocks don't concern us so long as the transactions we are honoring make it into the greatest-height chain.
Why don't you focus just on the realtime aspect and create a service that allows realtime bitcoin transactions on any website (and inside every app) trough an API, and ask for a smaller percentage (like ~2%, like a credit card company)?
There are already a number of merchant processing systems for Bitcoin including MtGox's payment api and Bit-Pay. Neither one supports instant transactions coming via the Bitcoin network (MtGox is instant if buyer and seller both have funds there), but the cultural aspect of helping Bitcoin users sell their wares easily was also an attractive one for this project.
Still, it's a great suggestion and will be considered for future development.
Also, this post was originally titled "CoinDL enables Bitcoin purchases in seconds (link to eBook example)" so your post was more on-topic than it seemed. Today I learned, titles can be renamed by somebody else on Hacker News.
So how can you achieve this low latency? Do you just base your decision "x has paid" on the still unsigned chain? That's quite risky and open for exploits, isn't it?
Also, what do you do if there are orphan blocks in the chain?
(Comment about coindl.com, not the book the article links to.)