JSONRPC-parity_pubsub-module.md

title
The `parity_pubsub` Module

JSON-RPC methods

• parity_subscribe
• parity_unsubscribe

JSON-RPC API Reference

parity_subscribe

Starts a subscription (on WebSockets / IPC / TCP transports) to results of calling some other RPC method. For every change in returned value of that RPC call a JSON-RPC notification with result and subscription ID will be sent to a client.

Below examples use wscat, a simple command line WebSockets client. Find out how to install and use it by visiting wscat GitHub repository.

An example notification received by subscribing to eth_getBalance RPC method:

{"jsonrpc":"2.0","method":"parity_subscription","params":{"subscription":"0x416d77337e24399d","result":["0xcd2a3d9f938e13cd947ec05abc7fe734df8dd826"]}}

You can unsubscribe using parity_unsubscribe RPC method. Subscriptions are also tied to a transport connection, disconnecting causes all subscriptions to be canceled.

Parameters

0. String - RPC method name
1. Array - Parameters passed to RPC method. (Optional, defaults to no parameters)

params: [
  "eth_getBalance",
  [
    "0xcd2a3d9f938e13cd947ec05abc7fe734df8dd826",
    "latest"
  ]
]

Returns

• String - Assigned subscription ID

Example

Request

wscat -c localhost:8546
>{"method":"parity_subscribe","params":["eth_getBalance",["0xcd2a3d9f938e13cd947ec05abc7fe734df8dd826","latest"]],"id":1,"jsonrpc":"2.0"}

Response

{
  "id": 1,
  "jsonrpc": "2.0",
  "result": "0x416d77337e24399d"
}

---

parity_unsubscribe

Unsubscribes from a subscription.

Parameters

0. String - Subscription ID

params: ["0x416d77337e24399d"]

Returns

• Boolean - whether the call was successful

Example

Request

wscat -c localhost:8546
>{"method":"parity_unsubscribe","params":["0x416d77337e24399d"],"id":1,"jsonrpc":"2.0"}

Response

{
  "id": 1,
  "jsonrpc": "2.0",
  "result": true
}