Service-transaction-checker-contract.md

title
Service Transaction Checker Contract

The service transaction checker contract is used by OpenEthereum to filter out transactions with zero gas price (aka service transactions).

Default behaviour (to which you can always revert by using --refuse-service-transactions command line option) is to discard all service transactions, coming from network. If 'registrar' contract is deployed and registered for your chain, you can alter default behaviour by:

1. deploying 'certifier' contract
2. registering address of this contract in registry with 'service_transaction_checker' name On startup, OpenEthereum will check if this contract is registered and will start checking the author of each service transaction, coming from the network. If the author is not certified to create service transactions, the transaction will be discarded. Otherwise, it will be accepted.

To register address, which is able to create service transactions, you should use certify method. To reverse this action, use revoke method. You can use certified method to check if address is certified for making service transactions.

Below is ABI of service transaction checker contract:

[
	{"constant":false,"inputs":[{"name":"_new","type":"address"}],"name":"setOwner","outputs":[],"payable":false,"type":"function"},
	{"constant":false,"inputs":[{"name":"_who","type":"address"}],"name":"certify","outputs":[],"payable":false,"type":"function"},
	{"constant":true,"inputs":[{"name":"_who","type":"address"},{"name":"_field","type":"string"}],"name":"getAddress","outputs":[{"name":"","type":"address"}],"payable":false,"type":"function"},
	{"constant":false,"inputs":[{"name":"_who","type":"address"}],"name":"revoke","outputs":[],"payable":false,"type":"function"},
	{"constant":true,"inputs":[],"name":"owner","outputs":[{"name":"","type":"address"}],"payable":false,"type":"function"},
	{"constant":true,"inputs":[],"name":"delegate","outputs":[{"name":"","type":"address"}],"payable":false,"type":"function"},
	{"constant":true,"inputs":[{"name":"_who","type":"address"},{"name":"_field","type":"string"}],"name":"getUint","outputs":[{"name":"","type":"uint256"}],"payable":false,"type":"function"},
	{"constant":false,"inputs":[{"name":"_new","type":"address"}],"name":"setDelegate","outputs":[],"payable":false,"type":"function"},
	{"constant":true,"inputs":[{"name":"_who","type":"address"}],"name":"certified","outputs":[{"name":"","type":"bool"}],"payable":false,"type":"function"},
	{"constant":true,"inputs":[{"name":"_who","type":"address"},{"name":"_field","type":"string"}],"name":"get","outputs":[{"name":"","type":"bytes32"}],"payable":false,"type":"function"}
]