The explanation of all the opcodes for the contact script does not list any IO operations for external (non-storage) data (at least none that I could see). However, in the list of Ethereum examples, the following is given:<p>"Crop insurance. One can easily make a financial derivatives contract but using a data feed of the weather instead of any price index. If a farmer in Iowa purchases a derivative that pays out inversely based on the precipitation in Iowa, then if there is a drought, the farmer will automatically receive money and if there is enough rain the farmer will be happy because their crops would do well."<p>Does somebody know how the contract would be able to read a data feed? I did not find anything in the language spec. Such a feature would be really interesting. On the one hand it would allow for a ton of interesting options (binding contracts to stock markets, emails, political events) on the other hand how would a contract behave if the required data url is gone (i.e. the weather data feed changed from weather.php?v1 to /v1/weather). Whats more, wouldn't there be strong incentives for man in the middle attacks to deliver wrong data? This sounds like a very powerful yet dangerous feature, so I'd love to learn more about the spec and reasoning behind this.
This version contains some mistakes and approximations. For a more up-to-date paper you should take a look at the White paper v2 draft [1].<p>A more formal and technical description is presented in the Yellow paper (also draft) [2].<p>[1] <a href="https://github.com/ethereum/wiki/wiki/Whitepaper-2-Draft" rel="nofollow">https://github.com/ethereum/wiki/wiki/Whitepaper-2-Draft</a><p>[2] <a href="http://gavwood.com/Paper.pdf" rel="nofollow">http://gavwood.com/Paper.pdf</a>
The 2007 book Rainbows End by Vernor Vinge addresses this topic from a science fiction perspective. A major plot element is the ability of individuals to enter into "affliances": digital, automatically-escrowed contracts between individuals providing small services in networks created on-demand to produce larger-scale goods and services. <a href="https://en.wikipedia.org/wiki/Rainbows_End" rel="nofollow">https://en.wikipedia.org/wiki/Rainbows_End</a> (copied my past comment at <a href="https://news.ycombinator.com/item?id=7287584" rel="nofollow">https://news.ycombinator.com/item?id=7287584</a>)<p>Also, here's a related past HN thread: <a href="https://news.ycombinator.com/item?id=7287155" rel="nofollow">https://news.ycombinator.com/item?id=7287155</a>
anyone who thinks GHOST is a good idea, has not understood Bitcoin at all. the whole point of the blocks is that nodes can work on the global state in a chain. so the idea that nodes should work on greedy subtrees is about the worst possible idea. Bitcoin solves not only the Byzantine generals problem, but a latency variance problem, to achieve logical broadcast. anyway, the author of this paper also believes that "anyone with reasonably high intelligence could have invented Bitcoin by random luck" [1]. well, no. there are many hidden problems which Bitcoin solves. the literature on quorum systems, distributed applications, etc. is very deep.<p>[1]
<a href="http://www.reddit.com/r/Bitcoin/comments/20oyes/brilliant_and_comprehensive_smackdown_of_leah/cg5ikzo" rel="nofollow">http://www.reddit.com/r/Bitcoin/comments/20oyes/brilliant_an...</a>
I hope they focus more on their Go client than the C++ one. Something like this needs to be as secure as it can get. No reason to have it vulnerable to memory leaks and such, if they don't have to.