# State channel WebSocket API

Messages on the WebSocket API have to follow JSON-RPC specification version 2.0. See: [www.jsonrpc.org](https://www.jsonrpc.org/specification)

The WebSocket API provides the following actions:

* [Off-chain update](#update)
* [On-chain deposit](#deposit)
* [On-chain withdrawal](#withdrawal)
* [Assume-minimum-depth](#assume-minimum-depth)
* [Contracts](#contracts)
* [Generic message](#generic-message)
* [Close mutual](#close-mutual)
* [Close solo](#close-solo)
* [Slash](#slash)
* [Settle](#settle)
* [Leave](#leave)
* [Snapshot](#snapshot)
* [Force progress](#force-progress)
* [Contract dry run](#contract-dry-run)
* [On-chain transactions](#on-chain-transactions)
* [Info messages](#info-messages)
* [System messages](#system-messages)
* [Signing error replies](#signing-error-replies)

## Update

Roles:

* Sender
* Acknowledger

### Sender trigger an update

* **method:** `channels.update.new`
* **params:**

| Name        | Type             | Description                                              | Required |
| ----------- | ---------------- | -------------------------------------------------------- | -------- |
| from        | string           | Participant's account to take coins from                 | Yes      |
| to          | string           | Participant's account to add coins to                    | Yes      |
| amount      | integer          | Amount of coins to transfer                              | Yes      |
| block\_hash | string           | The on-chain block hash to pin the off-chain environment | No       |
| meta        | array of strings | Meta information about the update                        | No       |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.update.new",
  "params": {
    "amount": 1,
    "from": "ak_2MGLPW2CHTDXJhqFJezqSwYSNwbZokSKkG7wSbGtVmeyjGfHtm",
    "to": "ak_nQpnNuBPQwibGpSJmjAah6r3ktAB7pG9JHuaGWHgLKxaKqEvC"
  }
}
```

### Sender receives a non-authenticated off-chain state

* **method:** `channels.sign.update`
* **params:**

| Name       | Type   | Description                                                                       | Required |
| ---------- | ------ | --------------------------------------------------------------------------------- | -------- |
| signed\_tx | string | `channel_offchain_tx` transaction wrapped in a `signed_tx` with no authentication | Yes      |
| updates    | list   | off-chain updates                                                                 | Yes      |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.sign.update",
  "params": {
    "channel_id": "ch_2Jkzb1BVaA888pdNgxoBjJWQKCMiJRxjLbG972dH6cSC3ULwGK",
    "data": {
      "signed_tx": "tx_+JU5AaEGrATZCq...",
      "updates": [
        {
          "amount": 1,
          "from": "ak_2MGLPW2CHTDXJhqFJezqSwYSNwbZokSKkG7wSbGtVmeyjGfHtm",
          "op": "OffChainTransfer",
          "to": "ak_nQpnNuBPQwibGpSJmjAah6r3ktAB7pG9JHuaGWHgLKxaKqEvC"
        }
      ]
    }
  },
  "version": 1
}
```

### Sender authenticates off-chain state response

* **method:** `channels.update`
* **params:**

| Name       | Type   | Description                                          | Required |
| ---------- | ------ | ---------------------------------------------------- | -------- |
| signed\_tx | string | solo-authenticated `channel_offchain_tx` transaction | Yes      |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.update",
  "params": {
    "signed_tx": "tx_+N8LAfhCuEA..."
  }
}
```

### Acknowledger receives a non-authenticated off-chain state

* **method:** `channels.sign.update_ack`
* **params:**

| Name       | Type   | Description                                          | Required |
| ---------- | ------ | ---------------------------------------------------- | -------- |
| signed\_tx | string | solo-authenticated `channel_offchain_tx` transaction | Yes      |
| updates    | list   | off-chain updates                                    | Yes      |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.sign.update_ack",
  "params": {
    "channel_id": "ch_2Jkzb1BVaA888pdNgxoBjJWQKCMiJRxjLbG972dH6cSC3ULwGK",
    "data": {
      "signed_tx": "tx_+JU5AaEGrATZCq...",
      "updates": [
        {
          "amount": 1,
          "from": "ak_2MGLPW2CHTDXJhqFJezqSwYSNwbZokSKkG7wSbGtVmeyjGfHtm",
          "op": "OffChainTransfer",
          "to": "ak_nQpnNuBPQwibGpSJmjAah6r3ktAB7pG9JHuaGWHgLKxaKqEvC"
        }
      ]
    }
  },
  "version": 1
}
```

### Acknowledger authenticated off-chain state response

* **method:** `channels.update_ack`
* **params:**

| Name       | Type   | Description                                        | Required |
| ---------- | ------ | -------------------------------------------------- | -------- |
| signed\_tx | string | co-authenticated `channel_offchain_tx` transaction | Yes      |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.update_ack",
  "params": {
    "signed_tx": "tx_+N8LAfhCuE..."
  }
}
```

### Update conflict

* **method:** `channels.conflict`
* **params:**

| Name        | Type   | Description                                          | Required |
| ----------- | ------ | ---------------------------------------------------- | -------- |
| channel\_id | string | channel id                                           | Yes      |
| data        | object | description of the last mutually authenticated state | Yes      |

* **data:**

| Name        | Type   | Description                                        | Required |
| ----------- | ------ | -------------------------------------------------- | -------- |
| channel\_id | string | channel id                                         | Yes      |
| round       | object | the round of the last mutually authenticated state | Yes      |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.conflict",
  "params": {
    "channel_id": "ch_zVDx935M1AogqZrNmn8keST2jH8uvn5kmWwtDqefYXvgcCRAX",
    "data": {
      "channel_id": "ch_zVDx935M1AogqZrNmn8keST2jH8uvn5kmWwtDqefYXvgcCRAX",
      "round": 5
    }
  },
  "version": 1
}
```

### Update error

* **error:**

| Name    | Type    | Description        | Required |
| ------- | ------- | ------------------ | -------- |
| message | string  | error message      | Yes      |
| code    | integer | error code         | Yes      |
| data    | json    | error description  | Yes      |
| request | json    | the failed request | Yes      |

* **data:**

| Name    | Type    | Description            | Required |
| ------- | ------- | ---------------------- | -------- |
| message | string  | JSON-RPC error message | Yes      |
| code    | integer | JSON-RPC error code    | Yes      |

#### Example

```javascript
{
  "channel_id": "ch_zVDx935M1AogqZrNmn8keST2jH8uvn5kmWwtDqefYXvgcCRAX",
  "error": {
    "code": 3,
    "data": [
      {
        "code": 1001,
        "message": "Insufficient balance"
      }
    ],
    "message": "Rejected",
    "request": {
      "jsonrpc": "2.0",
      "method": "channels.update.new",
      "params": {
        "amount": 10000000000000000,
        "from": "ak_nQpnNuBPQwibGpSJmjAah6r3ktAB7pG9JHuaGWHgLKxaKqEvC",
        "to": "ak_2MGLPW2CHTDXJhqFJezqSwYSNwbZokSKkG7wSbGtVmeyjGfHtm"
      }
    }
  },
  "id": null,
  "jsonrpc": "2.0",
  "version": 1
}
```

## Deposit

Roles:

* Depositor
* Acknowledger

### Depositor trigger a update

* **method:** `channels.deposit`
* **params:**

| Name        | Type             | Description                                                                                   | Required |
| ----------- | ---------------- | --------------------------------------------------------------------------------------------- | -------- |
| amount      | integer          | Amount of coins to deposit in the channel                                                     | Yes      |
| block\_hash | string           | The on-chain block hash to pin the off-chain environment                                      | No       |
| fee         | integer          | The on-chain transaction fee to be used. If not provided the FSM picks a value for the client | No       |
| gas\_price  | integer          | the gas\_price to be used for the fee computation                                             | No       |
| nonce       | integer          | the nonce to be used in the transaction                                                       | No       |
| meta        | array of strings | Meta information about the update                                                             | No       |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.deposit",
  "params": {
    "amount": 2
  }
}
```

### Depositor receives an non-authenticated deposit transaction

* **method:** `channels.sign.deposit_tx`
* **params:**

| Name        | Type   | Description  | Required |
| ----------- | ------ | ------------ | -------- |
| channel\_id | string | channel ID   | Yes      |
| data        | object | deposit data | Yes      |

* **data:**

| Name       | Type   | Description                                                                      | Required |
| ---------- | ------ | -------------------------------------------------------------------------------- | -------- |
| signed\_tx | string | `channel_deposit_tx` transaction wrapped in a `signed_tx` with no authentication | Yes      |
| updates    | list   | off-chain updates                                                                | Yes      |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.sign.deposit_tx",
  "params": {
    "channel_id": "ch_zVDx935M1AogqZrNmn8keST2jH8uvn5kmWwtDqefYXvgcCRAX",
    "data": {
      "signed_tx": "tx_+HIzAaEGgofGx...",
      "updates": [
        {
          "amount": 2,
          "from": "ak_2MGLPW2CHTDXJhqFJezqSwYSNwbZokSKkG7wSbGtVmeyjGfHtm",
          "op": "OffChainDeposit"
        }
      ]
    }
  },
  "version": 1
}
```

### Depositor authenticates deposit response

* **method:** `channels.deposit_tx`
* **params:**

| Name       | Type   | Description                                         | Required |
| ---------- | ------ | --------------------------------------------------- | -------- |
| signed\_tx | string | solo-authenticated `channel_deposit_tx` transaction | Yes      |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.deposit_tx",
  "params": {
    "signed_tx": "tx_+LwLAfhCuEB..."
  }
}
```

### Acknowledger receives a non-authenticated deposit transaction

* **method:** `channels.sign.deposit_ack`
* **params:**

| Name        | Type   | Description  | Required |
| ----------- | ------ | ------------ | -------- |
| channel\_id | string | channel ID   | Yes      |
| data        | object | deposit data | Yes      |

* **data:**

| Name       | Type   | Description                                         | Required |
| ---------- | ------ | --------------------------------------------------- | -------- |
| signed\_tx | string | solo-authenticated `channel_deposit_tx` transaction | Yes      |
| updates    | list   | off-chain updates                                   | Yes      |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.sign.deposit_ack",
  "params": {
    "channel_id": "ch_zVDx935M1AogqZrNmn8keST2jH8uvn5kmWwtDqefYXvgcCRAX",
    "data": {
      "signed_tx": "tx_+LwLAfhCuEB..."
      "updates": [
        {
          "amount": 2,
          "from": "ak_2MGLPW2CHTDXJhqFJezqSwYSNwbZokSKkG7wSbGtVmeyjGfHtm",
          "op": "OffChainDeposit"
        }
      ]
    }
  },
  "version": 1
}
```

### Acknowledger authenticates deposit response

* **method:** `channels.deposit_ack`
* **params:**

| Name       | Type   | Description                                       | Required |
| ---------- | ------ | ------------------------------------------------- | -------- |
| signed\_tx | string | co-authenticated `channel_deposit_tx` transaction | Yes      |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.deposit_ack",
  "params": {
    "signed_tx": "tx_+LwLAfhCu..."
  }
}
```

## Withdrawal

Roles:

* Withdrawer
* Acknowledger

### Withdrawer trigger a update

* **method:** `channels.withdraw`
* **params:**

| Name        | Type             | Description                                                                                   | Required |
| ----------- | ---------------- | --------------------------------------------------------------------------------------------- | -------- |
| amount      | integer          | Amount of coins to withdraw form the channel                                                  | Yes      |
| block\_hash | string           | The on-chain block hash to pin the off-chain environment                                      | No       |
| fee         | integer          | The on-chain transaction fee to be used. If not provided the FSM picks a value for the client | No       |
| gas\_price  | integer          | the gas\_price to be used for the fee computation                                             | No       |
| nonce       | integer          | the nonce to be used in the transaction                                                       | No       |
| meta        | array of strings | Meta information about the update                                                             | No       |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.withdraw",
  "params": {
    "amount": 2
  }
}
```

### Withdrawer receives a non-authenticated withdraw transaction

* **method:** `channels.sign.withdraw_tx`
* **payload:**

| Name        | Type   | Description     | Required |
| ----------- | ------ | --------------- | -------- |
| channel\_id | string | channel ID      | Yes      |
| data        | object | withdrawal data | Yes      |

* **data:**

| Name       | Type   | Description                                                                       | Required |
| ---------- | ------ | --------------------------------------------------------------------------------- | -------- |
| signed\_tx | string | `channel_withdraw_tx` transaction wrapped in a `signed_tx` with no authentication | Yes      |
| updates    | list   | off-chain updates                                                                 | Yes      |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.sign.withdraw_tx",
  "params": {
    "channel_id": "ch_zVDx935M1AogqZrNmn8keST2jH8uvn5kmWwtDqefYXvgcCRAX",
    "data": {
      "signed_tx": "tx_+HI0AaEG...",
      "updates": [
        {
          "amount": 2,
          "op": "OffChainWithdrawal",
          "to": "ak_2MGLPW2CHTDXJhqFJezqSwYSNwbZokSKkG7wSbGtVmeyjGfHtm"
        }
      ]
    }
  },
  "version": 1
}
```

### Withdrawer authenticates withdraw response

* **method:** `channels.withdraw_tx`
* **params:**

| Name       | Type   | Description                                        | Required |
| ---------- | ------ | -------------------------------------------------- | -------- |
| signed\_tx | string | co-authenticated `channel_withdraw_tx` transaction | Yes      |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.withdraw_tx",
  "params": {
    "signed_tx": "tx_+LwLAfhC..."
  }
}
```

### Acknowledger receives a non-authenticated withdraw transaction

* **method:** `channels.sign.withdraw_ack`
* **params:**

| Name        | Type   | Description     | Required |
| ----------- | ------ | --------------- | -------- |
| channel\_id | string | channel ID      | Yes      |
| data        | object | withdrawal data | Yes      |

* **data:**

| Name       | Type   | Description                                          | Required |
| ---------- | ------ | ---------------------------------------------------- | -------- |
| signed\_tx | string | solo-authenticated `channel_withdraw_tx` transaction | Yes      |
| updates    | list   | off-chain updates                                    | Yes      |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.sign.withdraw_ack",
  "params": {
    "channel_id": "ch_zVDx935M1AogqZrNmn8keST2jH8uvn5kmWwtDqefYXvgcCRAX",
    "data": {
      "signed_tx": "tx_+LwLAfhC..."
      "updates": [
        {
          "amount": 2,
          "op": "OffChainWithdrawal",
          "to": "ak_2MGLPW2CHTDXJhqFJezqSwYSNwbZokSKkG7wSbGtVmeyjGfHtm"
        }
      ]
    }
  },
  "version": 1
}
```

### Acknowledger authenticates withdraw response

* **method:** `channels.withdraw_ack`
* **params:**

| Name       | Type   | Description                                        | Required |
| ---------- | ------ | -------------------------------------------------- | -------- |
| signed\_tx | string | co-authenticated `channel_withdraw_tx` transaction | Yes      |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.withdraw_ack",
  "params": {
    "signed_tx": "tx_+LwLAf..."
  }
}
```

## Assume Minimum Depth

* **method:** `channels.assume_minimum_depth`
* **params:**

| Name     | Type   | Description                              | Required |
| -------- | ------ | ---------------------------------------- | -------- |
| tx\_hash | string | The on-chain hash of related transaction | yes      |

#### Example

```javascript
{
  "id": -576460752303421693,
  "jsonrpc": "2.0",
  "method": "channels.assume_minimum_depth",
  "params": {
    "tx_hash": "th_2ERU4LEe8Bn8x1iuw9vSh7iHys9t8zwt3Nq2oz5GQj9pAu9pur"
  }
}
```

## Contracts

### Contract create

* **method:** `channels.update.new_contract`
* **params:**

| Name         | Type             | Description                                                       | Required |
| ------------ | ---------------- | ----------------------------------------------------------------- | -------- |
| code         | contract code    | contract code                                                     | Yes      |
| call\_data   | call data        | call data for contract creation                                   | Yes      |
| vm\_version  | integer          | contract virtual machine version (vm for which code was compiled) | Yes      |
| abi\_version | integer          | contract virtual machine abi version                              | Yes      |
| deposit      | integer          | contract creation deposit                                         | Yes      |
| block\_hash  | string           | The on-chain block hash to pin the off-chain environment          | No       |
| meta         | array of strings | Meta information about the update                                 | No       |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.update.new_contract",
  "params": {
    "abi_version": 1,
    "call_data": "cb_AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACC5yVbyizFJqfWYeqUF89obIgnMVzkjQAYrtsG9n5+Z6gAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAnHQYrA==",
    "code": "cb_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",
    "deposit": 10,
    "vm_version": 3
  }
}
```

### Contract call

* **method:** `channels.update.call_contract`
* **params:**

| Name         | Type             | Description                                              | Required |
| ------------ | ---------------- | -------------------------------------------------------- | -------- |
| contract\_id | contract id      | contract to call                                         | Yes      |
| call\_data   | call data        | call data                                                | Yes      |
| abi\_version | integer          | call abi version                                         | Yes      |
| amount       | integer          | amount of coins to transfer to contract                  | Yes      |
| block\_hash  | string           | The on-chain block hash to pin the off-chain environment | No       |
| meta         | array of strings | Meta information about the update                        | No       |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.update.call_contract",
  "params": {
    "abi_version": 1,
    "amount": 0,
    "call_data": "cb_AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACBo8mdjOP9QiDmrpHdJ7/qL6H7yhPIH+z2ZmHAc1TiHxQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABgAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACo7dbVl",
    "contract_id": "ct_2Yy7TpPUs7SCm9jkCz7vz3nkb18zs78vcuVQGbgjRaWQNTWpm5"
  }
}
```

## Generic message

Roles:

* Sender
* Receiver

### Sender send message

* **method:** `channels.message`
* **params:**

| Name | Type   | Description        | Required |
| ---- | ------ | ------------------ | -------- |
| to   | string | Receiver's address | Yes      |
| info | string | Message body       | Yes      |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.message",
  "params": {
    "info": "hejsan",
    "to": "ak_nQpnNuBPQwibGpSJmjAah6r3ktAB7pG9JHuaGWHgLKxaKqEvC"
  }
}
```

### Receiver receives message

* **method:** `channels.message`
* **params:**

| Name        | Type   | Description                          | Required |
| ----------- | ------ | ------------------------------------ | -------- |
| channel\_id | string | channel id                           | Yes      |
| data        | object | data field that contains the message | Yes      |

* **data:**

| Name    | Type   | Description        | Required |
| ------- | ------ | ------------------ | -------- |
| message | object | the message itself | Yes      |

* **message:**

| Name        | Type   | Description        | Required |
| ----------- | ------ | ------------------ | -------- |
| channel\_id | string | channel id         | Yes      |
| from        | string | Sender's address   | Yes      |
| to          | string | Receiver's address | Yes      |
| info        | string | Message body       | Yes      |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.message",
  "params": {
    "channel_id": "ch_zVDx935M1AogqZrNmn8keST2jH8uvn5kmWwtDqefYXvgcCRAX",
    "data": {
      "message": {
        "channel_id": "ch_zVDx935M1AogqZrNmn8keST2jH8uvn5kmWwtDqefYXvgcCRAX",
        "from": "ak_2MGLPW2CHTDXJhqFJezqSwYSNwbZokSKkG7wSbGtVmeyjGfHtm",
        "info": "hejsan",
        "to": "ak_nQpnNuBPQwibGpSJmjAah6r3ktAB7pG9JHuaGWHgLKxaKqEvC"
      }
    }
  },
  "version": 1
}
```

## Close mutual

Roles:

* Closer
* Acknowledger

### Closer initiate mutual close

* **method:** `channels.shutdown`
* **params:**

| Name        | Type    | Description                                                                                   | Required |
| ----------- | ------- | --------------------------------------------------------------------------------------------- | -------- |
| block\_hash | string  | The on-chain block hash to pin the off-chain environment                                      | No       |
| fee         | integer | The on-chain transaction fee to be used. If not provided the FSM picks a value for the client | No       |
| gas\_price  | integer | the gas\_price to be used for the fee computation                                             | No       |
| nonce       | integer | the nonce to be used in the transaction                                                       | No       |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.shutdown",
  "params": {}
}
```

### Closer receives mutual close

* **method:** `channels.sign.shutdown_sign`
* **params:**

| Name        | Type   | Description  | Required |
| ----------- | ------ | ------------ | -------- |
| channel\_id | string | channel ID   | Yes      |
| data        | object | closing data | Yes      |

* **data:**

| Name       | Type   | Description                                                                           | Required |
| ---------- | ------ | ------------------------------------------------------------------------------------- | -------- |
| signed\_tx | string | `channel_close_mutual_tx` transaction wrapped in a `signed_tx` with no authentication | Yes      |
| updates    | list   | off-chain updates                                                                     | Yes      |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.sign.shutdown_sign",
  "params": {
    "channel_id": "ch_iNuPMRW1pCL17hXT8nHQgW1vMKfpBdsvztuYdM2VpPRh8PYVP",
    "data": {
      "signed_tx": "tx_+F01Aa...",
      "updates": []
    }
  },
  "version": 1
}
```

### Closer returns an authenticated mutual close

* **method:** `channels.shutdown_sign`
* **params:**

| Name       | Type   | Description                                              | Required |
| ---------- | ------ | -------------------------------------------------------- | -------- |
| signed\_tx | string | solo-authenticated `channel_close_mutual_tx` transaction | Yes      |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.shutdown_sign",
  "params": {
    "signed_tx": "tx_+KcLAfhC..."
  }
}
```

### Acknowledger receives mutual close

* **method:** `channels.sign.shutdown_sign_ack`
* **params:**

| Name        | Type   | Description  | Required |
| ----------- | ------ | ------------ | -------- |
| channel\_id | string | channel ID   | Yes      |
| data        | object | closing data | Yes      |

* **data:**

| Name       | Type   | Description                                              | Required |
| ---------- | ------ | -------------------------------------------------------- | -------- |
| signed\_tx | string | solo-authenticated `channel_close_mutual_tx` transaction | Yes      |
| updates    | list   | off-chain updates                                        | Yes      |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.sign.shutdown_sign_ack",
  "params": {
    "channel_id": "ch_iNuPMRW1pCL17hXT8nHQgW1vMKfpBdsvztuYdM2VpPRh8PYVP",
    "data": {
      "signed_tx": "tx_+KcLAfhC..."
      "updates": []
    }
  },
  "version": 1
}
```

### Acknowledger returns an authenticated mutual close

* **method:** `channels.shutdown_sign_ack`
* **params:**

| Name       | Type   | Description                                            | Required |
| ---------- | ------ | ------------------------------------------------------ | -------- |
| signed\_tx | string | co-authenticated `channel_close_mutual_tx` transaction | Yes      |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.shutdown_sign_ack",
  "params": {
    "signed_tx": "tx_+KcLAf..."
  }
}
```

## Snapshot

Roles:

* Snapshotter

### Snapshotter is prompted to snapshot (not mandatory step)

* **method:** `channels.on_chain_tx`
* **params:**

| Name | Type   | Description                                                        | Required |
| ---- | ------ | ------------------------------------------------------------------ | -------- |
| info | string | "can\_snapshot"                                                    | Yes      |
| tx   | string | the last on-chain transaction that could be disputed by a snapshot | Yes      |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.on_chain_tx",
  "params": {
    "channel_id": "ch_rb...",
    "data": {
      "info": "can_snapshot",
      "tx": "tx_+NIL...",
      "type": "channel_offchain_tx"
    }
  },
  "version": 1
}
```

### Snapshotter initiates solo snapshot

* **method:** `channels.snapshot_solo`
* **params:**

| Name       | Type    | Description                                                                                   | Required |
| ---------- | ------- | --------------------------------------------------------------------------------------------- | -------- |
| fee        | integer | The on-chain transaction fee to be used. If not provided the FSM picks a value for the client | No       |
| gas\_price | integer | the gas\_price to be used for the fee computation                                             | No       |
| nonce      | integer | the nonce to be used in the transaction                                                       | No       |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.snapshot_solo",
  "params": {}
}
```

### Snapshotter receives solo snapshot

* **method:** `channels.sign.snapshot_solo_tx`
* **params:**

| Name        | Type   | Description  | Required |
| ----------- | ------ | ------------ | -------- |
| channel\_id | string | channel ID   | Yes      |
| data        | object | closing data | Yes      |

* **data:**

| Name       | Type   | Description                                                                            | Required |
| ---------- | ------ | -------------------------------------------------------------------------------------- | -------- |
| signed\_tx | string | `channel_snapshot_solo_tx` transaction wrapped in a `signed_tx` with no authentication | Yes      |
| updates    | list   | empty list                                                                             | Yes      |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.sign.snapshot_solo_tx",
  "params": {
    "channel_id": "ch_s8RwBYpaPCPvUxvDsoLxH9KTgSV6EPGNjSYHfpbb4BL4qudgR",
    "data": {
      "signed_tx": "tx_+QGfNgGhBn...",
      "updates": []
    }
  },
  "version": 1
}
```

### Snapshotter returns an authenticated solo snapshot

* **method:** `channels.snapshot_solo_sign`
* **params:**

| Name       | Type   | Description                                               | Required |
| ---------- | ------ | --------------------------------------------------------- | -------- |
| signed\_tx | string | solo-authenticated `channel_snapshot_solo_tx` transaction | Yes      |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.snapshot_solo_sign",
  "params": {
    "signed_tx": "tx_+QHrCwH4Q..."
  }
}
```

## Force progress

Roles:

* Forcer

### Forcer initiates a force progress

* **method:** `channels.force_progress`
* **params:**

| Name         | Type        | Description                                                                | Required |
| ------------ | ----------- | -------------------------------------------------------------------------- | -------- |
| contract\_id | contract id | contract to call                                                           | Yes      |
| call\_data   | call data   | call data                                                                  | Yes      |
| abi\_version | integer     | call abi version                                                           | Yes      |
| amount       | integer     | amount of coins to transfer to contract                                    | Yes      |
| gas\_price   | integer     | the gas\_price to be used for the fee computation and the update execution | Yes      |
| gas          | integer     | gas limit, if not provided `1000000` is the default value                  | No       |
| nonce        | integer     | the nonce to be used in the transaction                                    | No       |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.force_progress",
  "params": {
    "abi_version":1,
    "amount":10,
    "call_data":"cb_AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACCzVg5SHSPanMS8lSeSX8SFfJMeAfEkyR6oKfQhD6XCTgAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA5gCcXw==",
    "contract_id":"ct_5XjcY6aaohWVHf6WSKcZKuMKYL3CfwopJRCnwqSaEgJUGrpbP",
    "gas_price":1000005554
  }
}
```

### Forcer receives a prepared force progress transaction to authenticate

* **method:** `channels.sign.force_progress_tx`
* **params:**

| Name        | Type   | Description  | Required |
| ----------- | ------ | ------------ | -------- |
| channel\_id | string | channel ID   | Yes      |
| data        | object | closing data | Yes      |

* **data:**

| Name       | Type   | Description                                                                             | Required |
| ---------- | ------ | --------------------------------------------------------------------------------------- | -------- |
| signed\_tx | string | `channel_force_progress_tx` transaction wrapped in a `signed_tx` with no authentication | Yes      |
| updates    | list   | a list of a single update                                                               | Yes      |

* **update**

| Name         | Type    | Description                                      | Required |
| ------------ | ------- | ------------------------------------------------ | -------- |
| amount       | integer | the coins amount given to the off-chain contract | Yes      |
| abi\_version | integer | abi version                                      | Yes      |
| call\_data   | integer | contract execution call data                     | Yes      |
| call\_stack  | list    | contract execution call stack                    | Yes      |
| caller\_id   | string  | ID of the caller                                 | Yes      |
| contract\_id | string  | contract ID to be executed                       | Yes      |
| gas          | integer | gas limit                                        | Yes      |
| gas\_price   | integer | gas price                                        | Yes      |
| op           | string  | "OffChainCallContract"                           | Yes      |

#### Example

```javascript
{
   "jsonrpc":"2.0",
   "method":"channels.sign.force_progress_tx",
   "params":{
      "channel_id":"ch_2FdiLKkRUdPw4oTRbB6i3M6pquogzWLABQjU373hizDbnD8gGC",
      "data":{
         "signed_tx":"tx_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",
         "updates":[
            {
               "abi_version":1,
               "amount":10,
               "call_data":"cb_AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACCzVg5SHSPanMS8lSeSX8SFfJMeAfEkyR6oKfQhD6XCTgAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA5gCcXw==",
               "call_stack":[

               ],
               "caller_id":"ak_Vu1cGq2d3Dpo9gP7pVJc8KMubXr8PjuX51b4yyJmFDcXgTZxT",
               "contract_id":"ct_55CN7nU2xnfkEUQbe9Aai4xwLEcRyTjYS2zmVpcHtFFqHLVX6",
               "gas":1000000,
               "gas_price":1000000000,
               "op":"OffChainCallContract"
            }
         ]
      }
   },
   "version":1
}
```

### Forcer returns an authenticated force progress transaction

* **method:** `channels.force_progress_sign`
* **params:**

| Name       | Type   | Description                                               | Required |
| ---------- | ------ | --------------------------------------------------------- | -------- |
| signed\_tx | string | solo-authenticated `channel_snapshot_solo_tx` transaction | Yes      |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.force_progress_sign",
  "params": {
    "signed_tx": "tx_+QkACwH4Qrh..."
  }
}
```

### Contract dry run

* **method:** `channels.dry_run.call_contract`
* **params:**

| Name         | Type             | Description                                              | Required |
| ------------ | ---------------- | -------------------------------------------------------- | -------- |
| contract\_id | contract id      | contract to call                                         | Yes      |
| call\_data   | call data        | call data                                                | Yes      |
| abi\_version | integer          | call abi version                                         | Yes      |
| amount       | integer          | amount of coins to transfer to contract                  | Yes      |
| block\_hash  | string           | The on-chain block hash to pin the off-chain environment | No       |
| meta         | array of strings | Meta information about the update                        | No       |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.dry_run.call_contract",
  "params": {
    "abi_version": 1,
    "amount": 0,
    "call_data": "cb_AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACBo8mdjOP9QiDmrpHdJ7/qL6H7yhPIH+z2ZmHAc1TiHxQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABgAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACo7dbVl",
    "contract_id": "ct_2Yy7TpPUs7SCm9jkCz7vz3nkb18zs78vcuVQGbgjRaWQNTWpm5"
  }
}
```

## On-chain transactions

* **method:** `channels.on_chain_tx`
* **params:**

| Name        | Type   | Description  | Required |
| ----------- | ------ | ------------ | -------- |
| channel\_id | string | channel ID   | Yes      |
| data        | object | closing data | Yes      |

* **data:**

| Name       | Type             | Description                                                  | Required |
| ---------- | ---------------- | ------------------------------------------------------------ | -------- |
| info       | string           | specific type of event                                       | Yes      |
| signed\_tx | string           | a mutually authenticated transaction that is posted on-chain | Yes      |
| type       | transaction type | Yes                                                          |          |

The `info` values could be:

* `"funding_signed"` - reported by the `initiator`, indicating that a `channel_create_tx` has been\
  singly authenticated by the `initiator` client, and sent to the `responder` for co-signing.
* `"funding_created"` - reported by the `responder`, indicating that a `channel_create_tx` has been\
  co-authenticated, and will be pushed to the mempool.
* `"deposit_signed"` - reported by the `depositor`, indicating that a `channel_deposit_tx` has been\
  singly authenticated by the `depositor` client, and sent to the `acknowledger` for co-signing.
* `"deposit_created"` - reported by the `acknowledger`, indicating that a `channel_deposit_tx` has been\
  co-authenticated, and will be pushed to the mempool.
* `"withdraw_signed"` - reported by the `withdrawer`, indicating that a `channel_withdraw_tx` has been\
  singly authenticated by the `withdrawer` client, and sent to the `acknowledger` for co-signing.
* `"withdraw_created"` - reported by the `acknowledger`, indicating that a `channel_withdraw_tx` has been\
  co-authenticated, and will be pushed to the mempool.
* `"channel_changed"` - reported by both parties, indicating that the fsm has detected a channel-related\
  transaction on-chain. Note that this will be reported also for the `channel_create_tx`, once it\
  appears on-chain. This means that each client will get *two* `on_chain_tx` reports for the\
  create, deposit, withdraw and close\_mutual transactions.
* `"close_mutual"` - reported by both parties, indicating that a `channel_close_mutual_tx` has been\
  co-authenticated, and will be pushed to the mempool.
* `"channel_closed"` - reported by both parties, when the on-chain channel state is detected to transition\
  to a `closed` state.
* `"solo_closing"` - reported by both parties, when the on-chain channel state is detected to transition\
  to a proper `solo_closing` state - that is, with the latest known state.
* `"can_slash"` or `"can_snapshot"`- reported by both parties, when the\
  on-chain channel state is seen to transition into an improper state -\
  that is, when there exists a later mutually authenticated state than the\
  one reported by either party on-chain. If the channel is not yet closing -\
  that could be a malicious `channel_force_progress_tx` and the reported`info` value is `"can_snapshot"`. If the malicious on-chain transaction is`channel_close_solo_tx` or the channel is already closing and a`channel_force_progress_tx` is received - then the `info` is `"can_slash"`.\
  Other transactions with an older `round` than the latest off-chain are not\
  considered harmful.

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.on_chain_tx",
  "params": {
    "channel_id": "ch_zVDx935M1AogqZrNmn8keST2jH8uvn5kmWwtDqefYXvgcCRAX",
    "data": {
      "info": "deposit_signed",
      "signed_tx": "tx_+KcLAf..."
      "type": "channel_deposit_tx"
    }
  },
  "version": 1
}
```

## Close solo

Roles:

* Closer

### Closer initiated solo close

* **method:** `channels.close_solo`
* **params:**

| Name       | Type    | Description                                                                                   | Required |
| ---------- | ------- | --------------------------------------------------------------------------------------------- | -------- |
| fee        | integer | The on-chain transaction fee to be used. If not provided the FSM picks a value for the client | No       |
| gas\_price | integer | the gas\_price to be used for the fee computation                                             | No       |
| nonce      | integer | the nonce to be used in the transaction                                                       | No       |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.close_solo",
  "params": {}
}
```

### Closer receives solo close

* **method:** `channels.sign.close_solo_sign`
* **params:**

| Name        | Type   | Description  | Required |
| ----------- | ------ | ------------ | -------- |
| channel\_id | string | channel ID   | Yes      |
| data        | object | closing data | Yes      |

* **data:**

| Name       | Type   | Description                                                                         | Required |
| ---------- | ------ | ----------------------------------------------------------------------------------- | -------- |
| signed\_tx | string | `channel_close_solo_tx` transaction wrapped in a `signed_tx` with no authentication | Yes      |
| updates    | list   | off-chain updates                                                                   | Yes      |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.sign.close_solo_sign",
  "params": {
    "channel_id": "ch_s8RwBYpaPCPvUxvDsoLxH9KTgSV6EPGNjSYHfpbb4BL4qudgR",
    "data": {
      "signed_tx": "tx_+QGfNgGhBn...",
      "updates": []
    }
  },
  "version": 1
}
```

### Closer returns an authenticated solo close

* **method:** `channels.close_solo_sign`
* **params:**

| Name       | Type   | Description                                            | Required |
| ---------- | ------ | ------------------------------------------------------ | -------- |
| signed\_tx | string | solo-authenticated `channel_close_solo_tx` transaction | Yes      |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.close_solo_sign",
  "params": {
    "signed_tx": "tx_+QHrCwH4Q..."
  }
}
```

## Slash

Roles:

* Slasher

### Slasher initiated slash

* **method:** \`channels.slash
* **params:**

| Name       | Type    | Description                                                                                   | Required |
| ---------- | ------- | --------------------------------------------------------------------------------------------- | -------- |
| fee        | integer | The on-chain transaction fee to be used. If not provided the FSM picks a value for the client | No       |
| gas\_price | integer | the gas\_price to be used for the fee computation                                             | No       |
| nonce      | integer | the nonce to be used in the transaction                                                       | No       |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.slash",
  "params": {}
}
```

### Slasher receives slash

* **method:** `channels.sign.slash_tx`
* **params:**

| Name        | Type   | Description  | Required |
| ----------- | ------ | ------------ | -------- |
| channel\_id | string | channel ID   | Yes      |
| data        | object | closing data | Yes      |

* **data:**

| Name       | Type   | Description                                                                    | Required |
| ---------- | ------ | ------------------------------------------------------------------------------ | -------- |
| signed\_tx | string | `channel_slash_tx` transaction wrapped in a `signed_tx` with no authentication | Yes      |
| updates    | list   | off-chain updates                                                              | Yes      |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.sign.slash_tx",
  "params": {
    "channel_id": "ch_s8RwBYpaPCPvUxvDsoLxH9KTgSV6EPGNjSYHfpbb4BL4qudgR",
    "data": {
      "signed_tx": "tx_+QLDCwHAuQ...",
      "updates": []
    }
  },
  "version": 1
}
```

### Slasher returns an authenticated slash

* **method:** \`channels.slash\_sign
* **params:**

| Name       | Type   | Description                                       | Required |
| ---------- | ------ | ------------------------------------------------- | -------- |
| signed\_tx | string | solo-authenticated `channel_slash_tx` transaction | Yes      |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.slash_sign",
  "params": {
    "signed_tx": "tx_+QMGCwH4Qr..."
  }
}
```

## Slash

Roles:

* Slasher

### Slasher is prompted to slash

* **method:** `channels.on_chain_tx`
* **params:**

| Name | Type   | Description                                         | Required |
| ---- | ------ | --------------------------------------------------- | -------- |
| info | string | "can\_slash"                                        | Yes      |
| tx   | string | the last on-chain transaction that could be slashed | Yes      |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.on_chain_tx",
  "params": {
    "channel_id": "ch_rb...",
    "data": {
      "info": "can_slash",
      "tx": "tx_+NIL...",
      "type": "channel_offchain_tx"
    }
  },
  "version": 1
}
```

### Slasher initiates slash

* **method:** `channels.slash`

#### Example

```javascript
{
  "id": -576460752303423374,
  "jsonrpc": "2.0",
  "method": "channels.slash"
}
```

### Slasher receives slash

* **method:** `channels.sign.slash`
* **params:**

| Name        | Type   | Description   | Required |
| ----------- | ------ | ------------- | -------- |
| channel\_id | string | channel ID    | Yes      |
| data        | object | slashing data | Yes      |

* **data:**

| Name       | Type   | Description                                                                 | Required |
| ---------- | ------ | --------------------------------------------------------------------------- | -------- |
| signed\_tx | string | `channel_slash` transaction wrapped in a `signed_tx` with no authentication | Yes      |
| updates    | list   | empty list of updates updates                                               | Yes      |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.sign.slash",
  "params": {
    "channel_id": "ch_s8RwBYpaPCPvUxvDsoLxH9KTgSV6EPGNjSYHfpbb4BL4qudgR",
    "data": {
      "signed_tx": "tx_+QGfNgGhBn...",
      "updates": []
    }
  },
  "version": 1
}
```

### Slasher returns an authenticated slash

* **method:** `channels.slash_sign`
* **params:**

| Name       | Type   | Description                                    | Required |
| ---------- | ------ | ---------------------------------------------- | -------- |
| signed\_tx | string | solo-authenticated `channel_slash` transaction | Yes      |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.slash_sign",
  "params": {
    "signed_tx": "tx_+QHrCwH4Q..."
  }
}
```

## Settle

Roles:

* Settler

### Settler initiates settle

* **method:** `channels.settle`
* **params:**

| Name       | Type    | Description                                                                                   | Required |
| ---------- | ------- | --------------------------------------------------------------------------------------------- | -------- |
| fee        | integer | The on-chain transaction fee to be used. If not provided the FSM picks a value for the client | No       |
| gas\_price | integer | the gas\_price to be used for the fee computation                                             | No       |
| nonce      | integer | the nonce to be used in the transaction                                                       | No       |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.settle",
  "params": {}
}
```

### Settler receives settle

* **method:** `channels.sign.settle_sign`
* **params:**

| Name        | Type   | Description | Required |
| ----------- | ------ | ----------- | -------- |
| channel\_id | string | channel ID  | Yes      |
| data        | object | settle data | Yes      |

* **data:**

| Name       | Type   | Description                                                                     | Required |
| ---------- | ------ | ------------------------------------------------------------------------------- | -------- |
| signed\_tx | string | `channel_settle_tx` transaction wrapped in a `signed_tx` with no authentication | Yes      |
| updates    | list   | off-chain updates                                                               | Yes      |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.sign.settle_sign",
  "params": {
    "channel_id": "ch_s8RwBYpaPCPvUxvDsoLxH9KTgSV6EPGNjSYHfpbb4BL4qudgR",
    "data": {
      "signed_tx": "tx_+F04AaE...",
      "updates": []
    }
  },
  "version": 1
}
```

### Settler returns an authenticated settle

* **method:** `channels.settle_sign`
* **params:**

| Name       | Type   | Description                                        | Required |
| ---------- | ------ | -------------------------------------------------- | -------- |
| signed\_tx | string | solo-authenticated `channel_settle_tx` transaction | Yes      |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.settle_sign",
  "params": {
    "signed_tx": "tx_+KcLAfhCuEBdI..."
  }
}
```

## Leave

Roles:

* Leaver
* Acknowledger

### Leaver initiates leave

* **method:** `channels.leave`

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.leave",
  "params": {}
}
```

#### Leaver and Acknowledger inform their clients

* **method:** `channels.leave`
* **params:**

| Name        | Type   | Description  | Required |
| ----------- | ------ | ------------ | -------- |
| channel\_id | string | channel ID   | Yes      |
| data        | object | closing data | Yes      |

* **data:**

| Name  | Type   | Description                                     | Required |
| ----- | ------ | ----------------------------------------------- | -------- |
| state | string | a mutually authenticated last state transaction | Yes      |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.leave",
  "params": {
    "channel_id": "ch_s8RwBYpaPCPvUxvDsoLxH9KTgSV6EPGNjSYHfpbb4BL4qudgR",
    "data": {
      "state": "tx_+QENCwH4hLh..."
    }
  },
  "version": 1
}
```

## Info messages

### Info

* **method:** `channels.info`
* **params:**

| Name        | Type   | Description | Required |
| ----------- | ------ | ----------- | -------- |
| channel\_id | string | channel ID  | Yes      |
| data        | object | info data   | Yes      |

* **data:**

| Name  | Type   | Description       | Required |
| ----- | ------ | ----------------- | -------- |
| event | string | event description | Yes      |

#### Example

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.info",
  "params": {
    "channel_id": "ch_zVDx935M1AogqZrNmn8keST2jH8uvn5kmWwtDqefYXvgcCRAX",
    "data": {
      "event": "own_deposit_locked"
    }
  },
  "version": 1
}
```

### Latest state

* **method:** `channels.get.offchain_state`

#### Response

* **result:**

| Field name       | Value                                                                            |
| ---------------- | -------------------------------------------------------------------------------- |
| `trees`          | channel state trees                                                              |
| `calls`          | channel call state tree                                                          |
| `half_signed_tx` | channel latest half authenticated tx or `''` if equal to latest authenticated tx |
| `signed_tx`      | channel latest mutually authenticated tx or `''` if not available                |

#### Example

**Request**

```javascript
{
  "id": -576460752303423469,
  "jsonrpc": "2.0",
  "method": "channels.get.offchain_state",
  "params": {}
}
```

**Response**

```javascript
{
  "channel_id": "ch_2Jkzb1BVaA888pdNgxoBjJWQKCMiJRxjLbG972dH6cSC3ULwGK",
  "id": -576460752303423469,
  "jsonrpc": "2.0",
  "result": {
    "calls": "cs_yYICbgGEwz8BwHtqgWY=",
    "half_signed_tx": "",
    "signed_tx": "tx_+QEhCwH4hLhA...",
    "trees": "ss_+Ks+AIrJggJtAY..."
  },
  "version": 1
}
```

### Latest contract state

* **method:** `channels.get.contract`
* **params:**

| Name   | Type   | Description               | Required |
| ------ | ------ | ------------------------- | -------- |
| pubkey | string | requested contract pubkey | Yes      |

#### Response

* **result:**

| Field name               | Value                                        |
| ------------------------ | -------------------------------------------- |
| `contract`               | object with contract details                 |
| `contract->id`           | contract id (equals to the requested pubkey) |
| `contract->owner_id`     | contract owner id                            |
| `contract->vm_version`   | contract vm version (integer)                |
| `contract->abi_version`  | contract ABI version (integer)               |
| `contract->active`       | "is contract active?" boolean                |
| `contract->referrer_ids` | referrer ids list                            |
| `contract->deposit`      | contract deposit                             |
| `contract_state`         | object with contract state                   |

#### Example

**Request**

```javascript
{
  "id": -576460752303423430,
  "jsonrpc": "2.0",
  "method": "channels.get.contract",
  "params": {
    "pubkey": "ct_uBX2jBr5bPEzD1uGFmV4i7JrGLtpEeLqPU29HvkZCv5iHcY4M"
  }
}
```

**Response**

```javascript
{
  "channel_id": "ch_zVDx935M1AogqZrNmn8keST2jH8uvn5kmWwtDqefYXvgcCRAX",
  "id": -576460752303423430,
  "jsonrpc": "2.0",
  "result": {
    "contract": {
      "abi_version": 1,
      "active": true,
      "deposit": 10,
      "id": "ct_uBX2jBr5bPEzD1uGFmV4i7JrGLtpEeLqPU29HvkZCv5iHcY4M",
      "owner_id": "ak_2MGLPW2CHTDXJhqFJezqSwYSNwbZokSKkG7wSbGtVmeyjGfHtm",
      "referrer_ids": [],
      "vm_version": 3
    },
    "contract_state": {
      "ck_AAAAAAAAAAAAAAAAAAAAAAA...": "cv_sbV3vNMnyznlXmwCa9anShs13mwGUMSuUe+rdZ5BW2YlrDqa",
      "ck_AAAAAAAAAAAAAAAAAAAAAAA...": "cv_sbV3vNMnyznlXmwCa9anShs13mwGUMSuUe+rdZ5BW2YlrDqa",
      "ck_AAAAAAAAAAAAAAAAAAAAAAA...": "cv_sbV3vNMnyznlXmwCa9anShs13mwGUMSuUe+rdZ5BW2YlrDqa",
      "ck_AAAAAAAAAAAAAAAAAAAAAAA...": "cv_AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA...",
      "ck_AAAAAAAAAAAAAAAAAAAAAAA...": "cv_AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA...",
      "ck_ABQG4Fg=": "cv_AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACDIq10LA12xQcUbe3+xpb7...",
      "ck_AZwSz9w=": "cv_AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACAAAAAAAAAAAAAAAAAAAAA...",
      "ck_AhzDreo=": "cv_AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAPJ9AW0"
    }
  },
  "version": 1
}
```

## System messages

### ping

* **method:** `channels.system`
* **params:**

| Name   | Type   | Description      | Required |
| ------ | ------ | ---------------- | -------- |
| action | string | the value "ping" | Yes      |

#### Response

* **method:** `channels.system`
* **params.data:**

| Field name | Value    |
| ---------- | -------- |
| `action`   | "system" |
| `tag`      | "pong"   |

#### Example

**Request**

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.system",
  "params": {
    "action": "ping"
  }
}
```

**Response**

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.system.pong",
  "params": {
    "channel_id": "ch_zVDx935M1AogqZrNmn8keST2jH8uvn5kmWwtDqefYXvgcCRAX",
    "data": {
      "action": "system",
      "tag": "pong"
    }
  },
  "version": 1
}
```

## Signing Error Replies

* **method:** `channels.initiator_sign | channels.responder_sign | channels.deposit_tx | channels.deposit_ack | channels.withdraw_tx | channels.withdraw_ack | channels.responder_sign | channels.snapshot_solo_tx | channels.snapshot_solo_sign | channels.shutdown_sign | channels.shutdown_sign_ack | channels.update | channels.update_ack | channels.close_solo_tx | channels.close_solo_sign | channels.slash_tx | channels.slash_sign | channels.settle_tx | channels.settle_sign`
* **params:**

| Name  | Type    | Description | Required |
| ----- | ------- | ----------- | -------- |
| error | integer | error code  | Yes      |

It is possible to return an error object in a signing reply. This will abort the ongoing sequence, and the FSM will\
fall back to the latest mutually-signed state. Currently defined error codes are:

* 1: validation error
* 2: conflict (typically, race condition)
* 3: timeout
* 4: abort
* 128...65535: user-defined

#### Example

```javascript
{
  "id": -576460752303423252,
  "jsonrpc": "2.0",
  "method": "channels.update",
  "params": {
    "error": 147
  }
}
```

#### Successful operation response

* **method:** `channels.info`
* **params:**

| Name        | Type   | Description  | Required |
| ----------- | ------ | ------------ | -------- |
| channel\_id | string | channel ID   | Yes      |
| data        | object | message data | Yes      |

* **params:**

| Name  | Type   | Description      | Required |
| ----- | ------ | ---------------- | -------- |
| event | string | `aborted_update` | Yes      |

* **data:**

| Name    | Type    | Description                            | Required |
| ------- | ------- | -------------------------------------- | -------- |
| message | string  | `Not allowed at current channel state` | Yes      |
| code    | integer | `1018`                                 | Yes      |

If the abort of the update is successful, the client that aborted receives a\
message for it:

```javascript
{
   "jsonrpc":"2.0",
   "method":"channels.info",
   "params":{
      "channel_id":"ch_95YaTDZAysRu3GkmW2yKkCK1H4fGtcttoj2qwFDfUSduTpCPf",
      "data":{
         "event":"aborted_update"
      }
   },
   "version":1
}
```

If the other participant had initiated the update that our client had aborted,\
the other participant's FSM will inform its client of each error, using a`conflict` report.

**Example**

```javascript
{
  "jsonrpc": "2.0",
  "method": "channels.conflict",
  "params": {
    "channel_id": "ch_Bx4x8rvNpeHe2LtnDNqyqCvguqX5jEeotUDk5cRXH3mEXzy77",
    "data": {
      "channel_id": "ch_Bx4x8rvNpeHe2LtnDNqyqCvguqX5jEeotUDk5cRXH3mEXzy77",
      "error_code": 147,
      "error_msg": "user-defined",
      "round": 5
    }
  },
  "version": 1
}
```

#### Unsuccessful operation response

* **method:** the request method
* **params:**

| Name        | Type   | Description       | Required |
| ----------- | ------ | ----------------- | -------- |
| channel\_id | string | channel ID        | Yes      |
| error       | object | error data object | Yes      |

* **error:**

| Name    | Type    | Description             | Required |
| ------- | ------- | ----------------------- | -------- |
| message | string  | `Rejected`              | Yes      |
| code    | integer | the error code provided | Yes      |
| data    | json    | error description       | Yes      |
| request | json    | the failed request      | Yes      |

* **data:**

| Name    | Type    | Description                            | Required |
| ------- | ------- | -------------------------------------- | -------- |
| message | string  | `Not allowed at current channel state` | Yes      |
| code    | integer | `1018`                                 | Yes      |

If the specified update abort can not be performed now, the request receives\
the following error:

```javascript
{
   "channel_id":"ch_95YaTDZAysRu3GkmW2yKkCK1H4fGtcttoj2qwFDfUSduTpCPf",
   "error":{
      "code":3,
      "data":[
         {
            "code":1018,
            "message":"Not allowed at current channel state"
         }
      ],
      "message":"Rejected",
      "request":{
         "jsonrpc":"2.0",
         "method":"channels.update",
         "params":{
           "error":147
         }
      }
   },
   "id":null,
   "jsonrpc":"2.0",
   "version":1
}
```