NXT cross chain transaction 3M to 5M bounty

[pinarello]

how can we help? what do you need?

Basically, ideas what the specific goals of CCT are regarding NXT.

Schedule:
0) new thread for this

1) define an API
 - heavily use case dependent
 - you should contribute what you want to achieve with cross-chain trading
 - price negotiations?

2) design questions
 - I fear we need something like a plugin architecture as transactions of different cryptocurrencies can look completely different
 - re-use of current AE infrastructure?
 - re-use of AT infrastructure?

3) implementation and test

5) deploy

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[allwelder]

well,attractive.

[jl777]

Here is my proposal on using AE for trading one crypto to another:

Let us assume that we have a NXT asset that corresponds to all the cryptos, eg. BTC, DOGE, AUR, etc. The following example will work with any pair, but for clarity, lets pick BTC and AUR. People who had BTC would be able to do a 1:1 swap for BTCAUR and people who had AUR would be able to do a 1:1 swap for AURBTC. The reverse is possible, these are just trading pairs that lets us use the NXT AE for people to trade. We definitely will need more decimal places in the prices, but the biggest change is that these "swap" assets need to be denominated in one of the cryptos and it usually wont be NXT.

The orderbook would be bids for AURBTC and the asks would be inverse of BTCAUR. This is exactly like forex trading pairs. The market settles on which currency the market is traded in and for crypto when BTC is involved, it is the one that the prices are in. So when a trade is done, here comes the required NXTcore changes!, instead of exchanging the asset for NXT, the asset is exchanged for the agreed amount of the underlying currency, in this case BTC.

The owner of AUR swaps for AURBTC, agrees to trade at 0.1 BTC and gets BTC asset, the other party gets the AURBTC, which is freely convertible to AUR.

I just realized that if we can make change to the NXT API for asset trading to specify the trading to be in units of an asset,then we dont have to bother with all the AURBTC 1:1 swaps! We just directly trade AUR assets for BTC assets and specify that the trade is denominated in BTC. With one simple change to NXT AE handling in the NXT core, we get to use NXT AE for trading any crypto against any crypto that the gateway supports.

This isnt exactly automatic cross chain, but I think it will be what people will want to do, namely trade cryptos. Just one change in NXT API and we can do this as soon as NXT core supports fractions!!

************
Now let us say that Mr 47...88 is not satisfied with the above and wants a solution without any gateway involved. In that case we wont have assurance that either party actually has what they say they want to trade, since presumably they are wanting to trade directly from their wallets. It also requires making a crypto to crypto exchange GUI and an interface that prompts the users to locally sign their transactions. Since each transaction would need manual intervention by both parties to complete, I would think that its use would be limited to large transactions only.

I think having the gateways provide an abstracted (and peer reviewed) interface to the external blockchains would allow an AT to manage the transaction process. Something has to interface with the bitcoind and it cant be the AT directly, so I am having trouble seeing how it is possible to do automated cross chain in a totally decentralized way.

************

Unless I hear otherwise, I will assume that Mr 47...88 wants NXT to be able to trade crypto to crypto within NXT. My top solution does that and actually has several advantages over a pure cross chain solution, eg. funds are verified and no need to invoke lengthy blockchain transactions for each trade. I will proceed on the assumption that this is acceptable and that we will be able to make the one change in the NXT API.

James

[indiamikezulu2]

Hey, guys!! I have posted here 'cause it's the current thread:

Mt. Barker Computers and Electronics in Western Australia is now accepting Nxt 'over the counter' for purchases.

We are 'indiamikezulu' (indiamikezulu dot com dot au), a hobby business devoted really to across-the-board cryptocurrency development in Australia rather than any particular crypto -- but we recognised the excellence of Nxt early on, hold coin, and are developing it 'on the ground.'

Actually, MBCE (my business partner's day job) is probably the only place in Australia that accepts more than two cryptos -- we're taking four.

Mark Blair (04 399 58791)

[l8orre]

Hea guys - I'd like to be on board with this too. I am getting my client finished, and then there will be a dedicated thing for this.

Current status on the AE client is that I have moved the server requests to POST and also included the latest three new api calls. The one thing that is making trouble is using https and POST - this means that I can't use web-wallets yet. But it occurred to me that that is a rather special case, and for using the AE you rather wnat to run YOUR nxt on your local node, so this can wait.

I have also created a proper QAbstractTableModel for display in table widgets. This was tough, but I have one now, and I can just replicate it for all OB tables. Will be a bit of work, but not serious.

So - AE client will be available soon!

James - sorry that I haven't had time to run dogecoind yet - but I'll catch up..

best,
l8orre

[pinarello]

Hey, guys!! I have posted here 'cause it's the current thread:

Mt. Barker Computers and Electronics in Western Australia is now accepting Nxt 'over the counter' for purchases.

We are 'indiamikezulu' (indiamikezulu dot com dot au), a hobby business devoted really to across-the-board cryptocurrency development in Australia rather than any particular crypto -- but we recognised the excellence of Nxt early on, hold coin, and are developing it 'on the ground.'

Actually, MBCE (my business partner's day job) is probably the only place in Australia that accepts more than two cryptos -- we're taking four.

Mark Blair (04 399 58791)

hi very nice!

do you have a link?

[4747...888]

Unless I hear otherwise, I will assume that Mr 47...88 wants NXT to be able to trade crypto to crypto within NXT.

Atomic crosschain is by definition NXT blockchain <-> BTC blockchain (or other pair).
It is not NXT blockchain <-> NXT AE <-> BTC blockchain.
If the first is impossible, please give the proof.

[ChuckOne]

Unless I hear otherwise, I will assume that Mr 47...88 wants NXT to be able to trade crypto to crypto within NXT.

Atomic crosschain is by definition NXT blockchain <-> BTC blockchain (or other pair).
It is not NXT blockchain <-> NXT AE <-> BTC blockchain.
If the first is impossible, please give the proof.

I agree.

I am still not available right now. But I think in 3 hours.

Please continue collecting ideas and use cases.

[Nxtblg]

Hey, guys!! I have posted here 'cause it's the current thread:

Mt. Barker Computers and Electronics in Western Australia is now accepting Nxt 'over the counter' for purchases.

We are 'indiamikezulu' (indiamikezulu dot com dot au), a hobby business devoted really to across-the-board cryptocurrency development in Australia rather than any particular crypto -- but we recognised the excellence of Nxt early on, hold coin, and are developing it 'on the ground.'

Actually, MBCE (my business partner's day job) is probably the only place in Australia that accepts more than two cryptos -- we're taking four.

Mark Blair (04 399 58791)

Well, that was quick! I'm amazed at how many Aussies are jumping on board the cyber train. You guys put us stodgy Canucks to shame 

[alxx77]

Unless I hear otherwise, I will assume that Mr 47...88 wants NXT to be able to trade crypto to crypto within NXT.

Atomic crosschain is by definition NXT blockchain <-> BTC blockchain (or other pair).
It is not NXT blockchain <-> NXT AE <-> BTC blockchain.
If the first is impossible, please give the proof.

But wouldn't it be better for NXT that everythig goes through AE as hub...?

[ChuckOne]

Hea guys - I'd like to be on board with this too. I am getting my client finished, and then there will be a dedicated thing for this.

Current status on the AE client is that I have moved the server requests to POST and also included the latest three new api calls. The one thing that is making trouble is using https and POST - this means that I can't use web-wallets yet. But it occurred to me that that is a rather special case, and for using the AE you rather wnat to run YOUR nxt on your local node, so this can wait.

I have also created a proper QAbstractTableModel for display in table widgets. This was tough, but I have one now, and I can just replicate it for all OB tables. Will be a bit of work, but not serious.

So - AE client will be available soon!

James - sorry that I haven't had time to run dogecoind yet - but I'll catch up..

best,
l8orre

Welcome. Great. I see there is much support for CCT.

Post your ideas regarding CCT here.

[ChuckOne]

Unless I hear otherwise, I will assume that Mr 47...88 wants NXT to be able to trade crypto to crypto within NXT.

Atomic crosschain is by definition NXT blockchain <-> BTC blockchain (or other pair).
It is not NXT blockchain <-> NXT AE <-> BTC blockchain.
If the first is impossible, please give the proof.

Alright, I would focus on this very use case first as 'NXT blockchain <-> NXT AE <-> BTC blockchain' might be very complex both in implementation and understanding. So would make this delicate feature very error-prone.

Let's if we can find a way to do the pair 'NXT <-> BTC' first. Generalization should be easy when considering BTC as a replaceable asset.

[ChuckOne]

Unless I hear otherwise, I will assume that Mr 47...88 wants NXT to be able to trade crypto to crypto within NXT.

Atomic crosschain is by definition NXT blockchain <-> BTC blockchain (or other pair).
It is not NXT blockchain <-> NXT AE <-> BTC blockchain.
If the first is impossible, please give the proof.

But wouldn't it be better for NXT that everythig goes through AE as hub...?

That might be true for the pricing issue. That is the data-structures and API calls for placing/cancelling orders could be re-used:

http://wiki.nxtcrypto.org/wiki/Nxt_API#Asset_exchange_operations

One thing that needs more consideration is the asset one could trade in case of CCT.

We would need two different types of assets: onchain-assets and offchain-assets.

Furthermore, offchain-assets need to be bound to certain code in NXT that allows trading with the specified asset. I.e., if a node wants to create a bitcoin transaction, code for creating such transaction is necessary. So is for every additional cryptocurrency as transaction formats and API of the regarding networks can differ.

All AE API calls would need to act according to the specified asset type. Is there a flaw in my logic?

[msin]

Unless I hear otherwise, I will assume that Mr 47...88 wants NXT to be able to trade crypto to crypto within NXT.

Atomic crosschain is by definition NXT blockchain <-> BTC blockchain (or other pair).
It is not NXT blockchain <-> NXT AE <-> BTC blockchain.
If the first is impossible, please give the proof.

But wouldn't it be better for NXT that everythig goes through AE as hub...?

It might be better for Nxt holders, but this is about doing a first, xchain tx.

[ChuckOne]

Unless I hear otherwise, I will assume that Mr 47...88 wants NXT to be able to trade crypto to crypto within NXT.

Atomic crosschain is by definition NXT blockchain <-> BTC blockchain (or other pair).
It is not NXT blockchain <-> NXT AE <-> BTC blockchain.
If the first is impossible, please give the proof.

But wouldn't it be better for NXT that everythig goes through AE as hub...?

It might be better for Nxt holders, but this is about doing a first, xchain tx.

Maybe, we need to clarify something:

There is no such thing as a crosschain transaction. This is crosschain trading.

[ChuckOne]

I need to leave now for an three hour or so. So, I will leave with more material to discuss:

Introductory:
https://bitcointalk.org/index.php?topic=345619.msg5462784#msg5462784

More detailed:
https://en.bitcoin.it/wiki/Atomic_cross-chain_trading


The basic idea goes as follows (publish = submit to the network):

1) Alice and Bob exchange unready transactions.

-> If Alice publishes a transaction, Alice will reveal a secret that Bob needs to publish his transaction

3) Alice publishes her transaction.
4) Bob can publish as well now.

[msin]

Unless I hear otherwise, I will assume that Mr 47...88 wants NXT to be able to trade crypto to crypto within NXT.

Atomic crosschain is by definition NXT blockchain <-> BTC blockchain (or other pair).
It is not NXT blockchain <-> NXT AE <-> BTC blockchain.
If the first is impossible, please give the proof.

But wouldn't it be better for NXT that everythig goes through AE as hub...?

It might be better for Nxt holders, but this is about doing a first, xchain tx.

Maybe, we need to clarify something:

There is no such thing as a crosschain transaction. This is crosschain trading.

Yes, good to clarify that.  Would this be a good time to explore Nxt parallel block chain for this application?

[gs02xzz]

I need to leave now for an hour or so. So, I will leave with more material to discuss:

Introductory:
https://bitcointalk.org/index.php?topic=345619.msg5462784#msg5462784

More detailed:
https://en.bitcoin.it/wiki/Atomic_cross-chain_trading


The basic idea goes as follows (publish = submit to the network):

1) Alice and Bob exchange unready transactions.

-> If Alice publishes a transaction, Alice will reveal a secret that Bob needs to publish his transaction

3) Alice publishes her transaction.
4) Bob can publish as well now.

This sounds like an autonomous contract to me. Whence a contract is established, as long as the parties in the contract do what they are supposed to do the contract will be executed in the order. I guess AT can play a role in it.

[swartzfeger]

Is this relevant at all to the discussion?

CoinWitness: https://bitcointalk.org/index.php?topic=277389.0

[ChuckOne]

I need to leave now for an hour or so. So, I will leave with more material to discuss:

Introductory:
https://bitcointalk.org/index.php?topic=345619.msg5462784#msg5462784

More detailed:
https://en.bitcoin.it/wiki/Atomic_cross-chain_trading


The basic idea goes as follows (publish = submit to the network):

1) Alice and Bob exchange unready transactions.

-> If Alice publishes a transaction, Alice will reveal a secret that Bob needs to publish his transaction

3) Alice publishes her transaction.
4) Bob can publish as well now.

This sounds like an autonomous contract to me. Whence a contract is established, as long as the parties in the contract do what they are supposed to do the contract will be executed in the order. I guess AT can play a role in it.

Sounds reasonable to me. Fees for executing the contract (we will pay per op) needs to be evenly split between the parties in order to prevent one party loosing more than the other one.