Generic questions on Codius

[tuloski]

Hi,
sorry if this is not the best place to discuss these topics but I didn't find a proper place.
I have a few questions which are puzzling me:

• Looking at Betty application, it seems that to coordinate multiple instances of the contract we have to code some "consensus" inside the contract itself. Isn't this a big limitation and a huge implementing challenge in case of complex contracts?
• Since users can pick their hosts, how can we prove that a contract is really decentralized since the hosts can belong to a single entity or to a minority?
• What happens when some hosts hosting my contract shut down or get DDoSed?
• If users can start/stop their contract whenever they want, how can the contracts be considered "decentralized". Who guarantees that a specific contract will run and be operative in 2 months for example?

I really don't see the advantages over renting N amazon instances and running my app in those instances. But maybe I'm not understanding well. I'm missing the "decentralization" and smart contract point.

[sharafian]

1. Right now you're right; it's very difficult to write your own consensus module. I wouldn't call it a limitation of the Codius system, though. Instead of building consensus into the Codius system directly, we can create libraries in multiple languages that provide consensus. This gives you the best of both worlds: you can write in your language of choice while still having robust decentralized applications.

2. When evaluating the decentralization of a contract, you wouldn't just look at the number of hosts. Instead, you'd look at their track records and their statistics to determine whether these hosts are repudable. If the contract is uploaded mainly to hosts who you mistrust, then you shouldn't use the contract. If you want to run a contract that as many people as possible will be willing to use, then you should choose hosts who are regarded highly by the most people. There may be services that rank the reputation of hosts in the future: you can already see that https://codiushosts.com is serving statistics about the hosts on the current network.

3. A host that goes down is no different than a host that is malicious. When you want to make your contract withstand DoS attacks, the best approach is to make it decentralized between many hosts with excellent uptime or DoS protections.

4. Users cannot stop their contracts whenever they want. Additionally, the original uploader is not the only person who can pay for a contract. Anyone who wants the contract to keep running could pay for more hosting, including the contract itself. Neither of those advantages apply to amazon instances, which is why one person can't use their amazon account to run a truly decentralized application.

[tuloski]

Thanks for the answer.

2. The problem is that there is no proof of decentralization. Imagine I run a contract on 10 reputable hosts. But maybe those hosts are run by myself or by a single group or organization. How can I prove my contract is really decentralized and not just run by a single group/person?
3. Well, in Ethereum you can have nodes popping and dying and there are no problems. In Codius it seems it's all about picking the right host (which can be tricky especially because they can decide their cost).
4. So once the contract is deployed it will run unless it runs out of money or was programmed to stop or all the hosts die?

[sharafian]

2. The information about who controls a node is part of their reputability. If you have a host that's been running for a long time but nobody knows who it is, it might be less reputable than a host that's been running by a short time but can present proof that it's owned by amazon, for instance. It puts more responsibility on the user than Ethereum, but gives you the ability to audit who's running your code much more thoroughly.

3. It's definitely a trade-off. Ethereum has the advantage that everything is decentralized out of the box. The disadvantage is that all code must be deterministic, and most meaningful programs are prohibitively expensive for the users. In Codius you need to put more thought into choosing a consensus mechanism and picking good hosts, but it's billions of times faster and cheaper.

4. Yeah, that's exactly right.

[MarkusTeufelberger]

Would a host that censors (e.g. mining software) contracts be considered more reputable or less reputable? Would this even be easily detectable by say codiushosts.com?

Edit: What is a Codius host legally anyways? A hosting provider? (after all, it's not much more than offering to host Docker containers)