Tendermint RPC

Tendermint RPC

The Tendermint RPC allows you to query transactions, blocks, consensus state, broadcast transactions, etc.

The latest Tendermint RPC documentation Tendermint supports the following RPC protocols:

  • URI over HTTP

  • JSON-RPC over HTTP

  • JSON-RPC over Websockets

The docs will contain an interactive Swagger interface.

URI/HTTP​

A GET request with arguments encoded as query parameters:

curl localhost:26657/block?height=5

RPC/HTTP​

JSONRPC requests can be POST'd to the root RPC endpoint via HTTP. See the list of supported Tendermint RPC endpoints using Swagger here.

RPC/Websocket​

Cosmos and Tendermint Events​

Events are objects that contain information about the execution of the application and are triggered after a block is committed. They are mainly used by service providers like block explorers and wallet to track the execution of various messages and index transactions. You can get the full list of event categories and values here.

More on Events:

Subscribing to Events via Websocket​

Tendermint Core provides a Websocket connection to subscribe or unsubscribe to Tendermint Events. To start a connection with the Tendermint websocket you need to define the address with the --rpc.laddr flag when starting the node (default tcp://127.0.0.1:26657):

cvmd start --rpc.laddr="tcp://127.0.0.1:26657"

Then, start a websocket subscription with ws

# connect to tendermint websocket at port 8080
ws ws://localhost:8080/websocket

# subscribe to new Tendermint block headers
> { "jsonrpc": "2.0", "method": "subscribe", "params": ["tm.event='NewBlockHeader'"], "id": 1 }

The type and attribute value of the query allow you to filter the specific event you are looking for. For example, an Ethereum transaction on CosVM (MsgEthereumTx) triggers an event of type ethermint and has sender and recipient as attributes. Subscribing to this event would be done like so:

{
    "jsonrpc": "2.0",
    "method": "subscribe",
    "id": "0",
    "params": {
        "query": "tm.event='Tx' AND ethereum.recipient='hexAddress'"
    }
}

where hexAddress is an Ethereum hex address (eg: 0x1122334455667788990011223344556677889900).

The generic syntax looks like this:

{
    "jsonrpc": "2.0",
    "method": "subscribe",
    "id": "0",
    "params": {
        "query": "tm.event='<event_value>' AND eventType.eventAttribute='<attribute_value>'"
    }
}

List of Tendermint Events​

The main events you can subscribe to are:

  • NewBlock: Contains events triggered during BeginBlock and EndBlock.

  • Tx: Contains events triggered during DeliverTx (i.e. transaction processing).

  • ValidatorSetUpdates: Contains validator set updates for the block.

TIP

👉 The list of events types and values for each Cosmos SDK module can be found in the Modules Specification section. Check the Events page to obtain the event list of each supported module on CosVM

List of all Tendermint event keys:

Below is a list of values that you can use to subscribe for the tm.event type:

Example​

ws ws://localhost:26657/websocket
> { "jsonrpc": "2.0", "method": "subscribe", "params": ["tm.event='ValidatorSetUpdates'"], "id": 1 }

Example response:

{
    "jsonrpc": "2.0",
    "id": 0,
    "result": {
        "query": "tm.event='ValidatorSetUpdates'",
        "data": {
            "type": "tendermint/event/ValidatorSetUpdates",
            "value": {
              "validator_updates": [
                {
                  "address": "09EAD022FD25DE3A02E64B0FE9610B1417183EE4",
                  "pub_key": {
                    "type": "tendermint/PubKeyEd25519",
                    "value": "ww0z4WaZ0Xg+YI10w43wTWbBmM3dpVza4mmSQYsd0ck="
                  },
                  "voting_power": "10",
                  "proposer_priority": "0"
                }
              ]
            }
        }
    }
}

TIP

Note: When querying Ethereum transactions versus Cosmos transactions, the transaction hashes are different. When querying Ethereum transactions, users need to use event query. Here's an example with the CLI:

curl -X GET "http://localhost:26657/tx_search?query=ethereum_tx.ethereumTxHash%3D0x8d43464891fac6c113e809e14dff1a3e608eae124d629799e42ca0e36562d9d7&prove=false&page=1&per_page=30&order_by=asc" -H "accept: application/json"

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