nwaku/docs/tutorial/jsonrpc-api.md

Waku v2 JSON-RPC API Basic Tutorial

Background

This tutorial provides step-by-step instructions on how to start a wakunode2 with the JSON-RPC API for basic peer-to-peer messaging using publish-subscribe (pubsub) patterns. Libp2p pubsub-functionality is provided in Waku v2 and accessed via the Relay API. Debugging methods are accessed via the Debug API.

Setup

Ensure you have built and run wakunode2 as per these instructions.

By default a running wakunode2 will expose a JSON-RPC API on the localhost (127.0.0.1) at port 8545. It is possible to change this configuration by setting the rpc-address and rpc-port options when running the node:

./build/wakunode2 --rpc-address:127.0.1.1 --rpc-port:8546

It is also possible to connect to one of our testnets by specifying a staticnode when running the node:

./build/wakunode2 --staticnode:<multiaddr>

where <multiaddr> is the multiaddress of a testnet node, e.g. the dingpu cluster node at

/ip4/134.209.139.210/tcp/60000/p2p/16Uiu2HAmJb2e28qLXxT5kZxVUUoJt72EMzNGXB47Rxx5hw3q4YjS

Calling JSON-RPC methods

One way to access JSON-RPC methods is by using the cURL command line tool. For example:

curl -d '{"jsonrpc":"2.0","id":"id","method":"<method-name>", "params":[<params>]}' --header "Content-Type: application/json" http://localhost:8545

where <method-name> is the name of the JSON-RPC method to call and <params> is a comma-separated Array of parameters to pass as arguments to the selected method. This assumes that the API is exposed on the localhost at port 8545 (the default configuration). See this page for a full list of supported methods and parameters.

Perform a health check

You can perform a basic health check to verify that the wakunode2 and API is up and running by calling the get_waku_v2_debug_v1_info method with no parameters. A successful response contains the node's multiaddress.

Example request

{
  "jsonrpc": "2.0",
  "id": "id",
  "method": "get_waku_v2_debug_v1_info",
  "params": []
}

Example response

The response

{
  "jsonrpc": "2.0",
  "id": "id",
  "result": {
    "listenStr": "/ip4/0.0.0.0/tcp/60000/p2p/16Uiu2HAm9R5sa7ivrCFLvGtLfc6WSyeHjiofdjZSHahJq1andKEG"
  },
  "error": null
}

indicates that the wakunode2 is running and provides its multiaddress.

Subscribe to a pubsub topic

You can subscribe to pubsub topics by calling the post_waku_v2_relay_v1_subscriptions method with an array of topic(s) as parameter. Pubsub topics are in String format.

Example request

{
  "jsonrpc": "2.0",
  "id": "id",
  "method": "post_waku_v2_relay_v1_subscriptions",
  "params": [
    [
      "my_topic_1",
      "my_topic_2",
      "my_topic_3"
    ]
  ]
}

Example response

The response

{
  "jsonrpc": "2.0",
  "id": "id",
  "result": true,
  "error": null
}

indicates that the wakunode2 successfully subscribed to all three requested topics.

Publish to a pubsub topic

To publish a message to a pubsub topic, call the post_waku_v2_relay_v1_message method with the target topic and publishable message as parameters. The message payload must be stringified as a hexadecimal string and wrapped in a WakuRelayMessage Object. Besides the published payload, a WakuRelayMessage can also contain an optional contentTopic that falls outside the scope of this tutorial. See the WakuFilter specification for more information.

Example request

{
  "jsonrpc": "2.0",
  "id": "id",
  "method": "post_waku_v2_relay_v1_message",
  "params": [
    "my_topic_1",
    {
      "payload": "0x1a2b3c4d5e6f",
      "timestamp": 1626813243.916377
    }
  ]
}

Example response

The response

{
  "jsonrpc": "2.0",
  "id": "id",
  "result": true,
  "error": null
}

indicates that the message payload was successfully published to "my_topic_1".

Read new messages from a subscribed pubsub topic

Use the get_waku_v2_relay_v1_messages method to retrieve the messages received on a subscribed pubsub topic. The queried topic is passed as parameter. This will only return new messages received after the last time this method was called. Repeated calls to get_waku_v2_relay_v1_messages can therefore be used to continuously poll a topic for new messages.

Example request

{
  "jsonrpc": "2.0",
  "id": "id",
  "method": "get_waku_v2_relay_v1_messages",
  "params": [
    "my_topic_1"
  ]
}

Example response

The response is an Array of WakuMessage objects.

{
  "jsonrpc": "2.0",
  "id": "id",
  "result": [
    {
      "payload": "0xaabbccddeeff",
      "contentTopic": 0,
      "version": 0
    },
    {
      "payload": "0x112233445566",
      "contentTopic": 0,
      "version": 0
    }
  ],
  "error": null
}

Calling the same method again returns

{
  "jsonrpc": "2.0",
  "id": "id",
  "result": [],
  "error": null
}

indicating that no new messages were received on the subscribed topic.

Unsubscribe from a pubsub topic

To unsubscribe from pubsub topics, call the delete_waku_v2_relay_v1_subscriptions method with an array of topic(s) as parameter.

Example request

{
  "jsonrpc": "2.0",
  "id": "id",
  "method": "delete_waku_v2_relay_v1_subscriptions",
  "params": [
    [
      "my_topic_1",
      "my_topic_2"
    ]
  ]
}

Example response

The response

{
  "jsonrpc": "2.0",
  "id": "id",
  "result": true,
  "error": null
}

indicates that the wakunode2 successfully unsubscribed from both topics.