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


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.kleros.io/integrations/types-of-integrations/1.-dispute-resolution-integration-plan/channel-partners/how-to-use-reality.eth-+-kleros-as-an-oracle.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.