Merge pull request #801 from ligi/add_canry_erc

Canary Interface ERC

EIPS/eip-801.md

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+## Preamble
+
+    EIP: 801
+    Title: ERC-801 Canary Standard
+    Author: ligi <ligi@ligi.de>
+    Type: Standard
+    Category: ERC
+    Status: Draft
+    Created: 2017-12-16
+
+
+## Simple Summary
+
+A standard interface for canary contracts.
+
+## Abstract
+
+The following standard allows the implementation of canaries within contracts.
+This standard provides basic functionality to check if a canary is alive, keeping the canary alive and optionally manage feeders.
+
+## Motivation
+
+The canary can e.g. be used as a [warrant canary](https://en.wikipedia.org/wiki/Warrant_canary).
+A standard interface allows other applications to easily interface with canaries on Ethereum - e.g. for visualizing the state, automated alarms, applications to feed the canary or contracts (e.g. insurance) that use the state.
+
+## Specification
+
+### Methods
+
+#### isAlive()
+
+Returns if the canary was fed properly to signal e.g. that no warrant was received.
+
+``` js
+function isAlive() constant returns (bool alive)
+```
+
+#### getBlockOfDeath()
+
+Returns the block the canary died.
+Throws if the canary is alive.
+
+``` js
+function getBlockOfDeath() constant returns (uint256 block)
+```
+
+#### getType()
+
+Returns the type of the canary:
+
+* `1` = Simple (just the pure interface as defined in this ERC)
+* `2` = Single feeder (as defined in ERC-TBD)
+* `3` = Single feeder with bad food (as defined in ERC-TBD)
+* `4` = Multiple feeders (as defined in ERC-TBD)
+* `5` = Multiple mandatory feeders (as defined in ERC-TBD)
+* `6` = IOT (as defined in ERC-TBD)
+
+`1` might also be used for a special purpose contract that does not need a special type but still wants to expose the functions and provide events as defined in this ERC.
+
+``` js
+function getType() constant returns (uint8 type)
+```
+
+### Events
+
+#### RIP
+
+MUST trigger when the contract is called the first time after the canary died.
+
+``` js
+event RIP()
+```
+
+## Implementation
+
+TODO
+
+## Copyright
+Copyright and related rights waived via [CC0](https://creativecommons.org/publicdomain/zero/1.0/).