CryptoCoinWatch

Ethereum datafeed to watch the amount received of crypto currencies. This data can be subsequently used by CFDs, escrows, betting contracts, etc.

DApp

The CryptoCoinWatch DApp lets you inspect a datafeed and allows you to watch a new address. See above screenshot for an impression. This is for development and testing purposes only, as normally contracts will directly communicate with the contract itself.

Open the DApp in your Ethereum client (AlethZero POC6): http://ethercasts.github.io/cryptocoinwatch/frontend/

Contract

The contract cryptocoinwatch.se allows 3rd parties to request the datafeed to watch the getreceivedbyaddress value of a Bitcoin (or other altcoin) address.

When providing an address, it should be converted to the Base58Check format and prefixed with the version byte. So for the Bitcoin multisig address 36PrZ1KHYMpqSyAQXSG8VwbUiq2EogxLo2 the address to use is 0x053399bc19f2b20473d417e31472c92947b59f95f8

This conversion can be done with pybtctool:

$ pybtctool b58check_to_hex 36PrZ1KHYMpqSyAQXSG8VwbUiq2EogxLo2
3399bc19f2b20473d417e31472c92947b59f95f8
$ pybtctool get_version_byte 36PrZ1KHYMpqSyAQXSG8VwbUiq2EogxLo2
5

The contract storage can be expected to get some metadata, there are not (yet) exposed via an API:

• 0x10 - Contract owner
• 0x11 - Data source (ie "blockchain.info")
• 0x12 - Minimum number of confirmations (default to 6)
• 0x13 - Timestamp when any value in the the contract was last updated

The contract can be called with a couple commands. Note that you should convert the strings to integers yourself, as there is a dispute on the correct way of string padding in the various Ethereum clients (this will be resolved soon, hopefully, see ethereum/aleth#268)

WATCH

Usage: 0x7761746368 address

A caller can request an address to be watched by the datafeed.

GETRECEIVEDBYADDRESS

Usage: 0x6765747265636569766564627961646472657373 address

Returns an array with 2 elements; the getreceivedbyaddress value and the timestamp when this was last updated.

SETRECEIVEDBYADDRESS

Usage: 0x7365747265636569766564627961646472657373 address value

Sets the getreceivedbyaddress value for the given address, can only be executed by the contract owner.

SUICIDE

Usage: 0x73756963696465

Allows the contract owner (creator) to remove the contract from the blockchain.

Watchdog

The watchdog.py service is the off-chain counterpart to the above contract. It lets you create a datafeed contract and poll its state, as well as offer some testing utilities (getreceivedbyaddress, status, transact and watch).

The service can be executed from the command line:

usage: watchdog.py [-h]
                   {create,getreceivedbyaddress,poll,status,transact,watch}
                   ...

positional arguments:
  {create,getreceivedbyaddress,poll,status,transact,watch}
                        sub-command help
    create              create the contract
    getreceivedbyaddress
                        getreceivedbyaddress
    poll                poll the contract state
    status              display the eth node status
    transact            transact ether to destination
    watch               watch the address

optional arguments:
  -h, --help            show this help message and exit

The watchdog will connect to the eth JSONRPC interface, http://127.0.0.1:8080 by default, but this can be customised by setting the environment variable ETH_JSONRPC_URI.

License

Modified MIT License - (c) 2014 - EtherCasts. See License file.