> For the complete documentation index, see [llms.txt](https://docs-legacy.kleros.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs-legacy.kleros.io/integrations/types-of-integrations/1.-dispute-resolution-integration-plan/channel-partners/how-to-use-reality.eth-+-kleros-as-an-oracle.md).

# How to use Reality.eth + Kleros as an oracle

When you want your app to get data from a subjective oracle

In use cases where a subjective oracle is required to give an answer on-chain about the occurrence of an event (e.g.: Prediction Markets, DAO Governance, etc...), your application might want to use the combination of [Reality.eth](https://reality.eth.link/) bond escalation mechanism with Kleros arbitration services to have a decentralized and fair source of truth.

[Learn more about this use case](https://kleros.gitbook.io/docs/products/oracle)

### Architecture

![High-level architecture overview of an app using Reality.eth + Kleros as an oracle](https://3167298399-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-LPbPWuMtwBOvW0iuxyw%2Fuploads%2Fgit-blob-d086b5709a3e8e6bca4c1b867b60a103f5c48a57%2FUntitled%20Diagram%20\(2\).png?alt=media)

* **Your app requiring a subjective oracle**

  This is your smart contract that will only interact directly with Reality.eth contract.
* **Reality.eth**

  Bond escalation mechanism contract where anyone can submit a question with a required minimum bond to submit answers. It is possible to request arbitration by a 3rd party at any point after a first answer is submitted.

  [Documentation](https://reality.eth.link/app/docs/html) - [Github](https://github.com/realitio/realitio-contracts/tree/master/truffle/contracts)
* **Reality.eth < > Kleros Arbitrator proxy**

  Contract acting as a proxy between Reality.eth and Kleros Court contract. It acts as a Reality.eth arbitrator by creating corresponding disputes in Kleros Courts and submitting the final ruling as an answer in the proper format. This contract is configured with a number of initial votes required and a specific sub-court where the dispute will be raised (ex: 5 initial votes by jurors in Blockchain > Technical court). You can use one already used by other apps or ask the cooperative Kleros team to deploy a new one fit for your needs.

  [Github](https://github.com/kleros/realitio-arbitrator-with-appeals)
* **Kleros**

  [Kleros Court](https://kleros.gitbook.io/docs/products/court) contract that will adjudicate on the dispute by drawing jurors and publishing a final ruling about the case.

### Requirements

To use this service, you just need to ensure that:

* your smart contract is compatible with the Reality.eth contract interface (check their [documentation](https://reality.eth.link/app/docs/html/contracts.html) and [repo](https://github.com/realitio/realitio-contracts/tree/master/truffle/contracts))
  * If your contract is in development, Cooperative Kleros team can support you in making it compatible.
  * If your contract is already live, Cooperative Kleros team can support you in building a connector for it.
* you submit the address of the Reality.eth<>Kleros arbitrator proxy you want to use as `arbitrator`when you ask a question. The arbitrator proxy will be set up with an initaial number of votes to be requested and a specific subcourt in whichcases will be raised. The Cooperative Kleros team can help select the right arbitrator for your use case or deploy a new one for you.

```typescript
function askQuestion ( uint256 template_id, string question, address arbitrator, uint32 timeout, uint32 opening_ts, uint256 nonce ) external payable returns ( bytes32 );
```

{% hint style="info" %}
**Reality.eth <> Kleros Arbitrator Proxy deployments**

* (Current version) Mainnet: General Court - 0x728cba71a3723caab33ea416cb46e2cc9215a596
* (Current version) Mainnet: Technical Court - 0xf72cfd1b34a91a64f9a98537fe63fbab7530adca
* (Current version) Polygon: General Court - \
  0x5afa42b30955f137e10f89dfb5ef1542a186f90e
* (Current version) Mumbai: General Court - \
  0xead0c9a4baeaf9b5221358539173602fa12b4b7d
* (Current version) Kovan: Non-technical Court - 0xDEd12537dA82C1019b3CA1714A5d58B7c5c19A04

**Deprecated**

* (Old version without appeals) [Mainnet](https://etherscan.io/address/0xd47f72a2d1d0E91b0Ec5e5f5d02B2dc26d00A14D)
  * 500 votes in general Court
* (Old version without appeals) [Kovan](https://kovan.etherscan.io/address/0xa6ead513d05347138184324392d8ceb24c116118)
  {% endhint %}

### Sequence Diagram

![](https://3167298399-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-LPbPWuMtwBOvW0iuxyw%2Fuploads%2Fgit-blob-7ee031f683c642ccad962d750a55ffd565e4febb%2FKleros%20Reality.png?alt=media)