Connecting to endpoints

By default, Lisk exposes a range of endpoints to communicate with a node.

Apart from that, Modules and Plugins of a blockchain client can also expose endpoints as described in the guides about implementing endpoints for a module and creating an endpoint for a plugin, respectively.

On this page, you’ll learn about how the aforementioned endpoints can be invoked within the Lisk ecosystem.

Invoking via API client

The API client simplifies sending API requests to a blockchain node.

External services communicate to a blockchain node via RPCs.

RPC-based interfaces i.e., IPC, WS, or HTTP allow applications to invoke RPC endpoints.

An API client can be imported into any JS client application as shown in the following snippets.

To conveniently communicate with a blockchain node, use the apiClient included in the @liskhq/lisk-client and the lisk-sdk packages.

  • WS API client example

  • IPC API client example

  • HTTP cURL

const { apiClient } = require('@liskhq/lisk-client');
let clientCache;
const nodeAPIURL = 'ws://localhost:7887/rpc-ws';

const getClient = async () => {
    if (!clientCache) {
        clientCache = await apiClient.createWSClient(nodeAPIURL);
    }
    return clientCache;
};


const blockId = "0f4ea1c3cfb61b99d387b26aaadf57936a528e5c713c6e55aa06f4d621b7e6f0";

getClient().then((client) => {
    client.invoke("chain_getBlockByID", {
        id: blockId
    }).then(res => {
        console.log("Result: ", res);
    });
});
const { apiClient } = require('@liskhq/lisk-client');
let clientCache;

const getClient = async () => {
    if (!clientCache) {
        // The data path to the blockchain client should be passed here
        // In our case, we are passing data path for the "hello_client"
        clientCache = await apiClient.createIPCClient('~/.lisk/hello_client');
    }
    return clientCache;
};

const blockId = "0f4ea1c3cfb61b99d387b26aaadf57936a528e5c713c6e55aa06f4d621b7e6f0";

getClient().then((client) => {
    client.invoke("chain_getBlockByID", {
        id: blockId
    }).then(res => {
        console.log("Result: ", res);
    });
});

Apart from the WS and IPC method, Lisk endpoints also support HTTP requests and response mechanisms. With a JSON RPC 2.0 based format, any endpoint can be invoked using a cURL request. For example, as shown below:

curl --location --request POST 'http://localhost:7887/rpc' \
--header 'Content-Type: application/json' \
--data-raw '{
    "jsonrpc": "2.0",
    "id": "1",
    "method": "chain_getBlockByHeight",
    "params": {
        "height": 2291
    }
}'

Lisk also supports invoking endpoints from within the blockchain client. For more information, check out the syncing and storing example for the HelloInfoPlugin. Specifically, the line of code shown in the following example:

private async _syncChainEvents(): Promise<void> {
    // 1. Get the latest block height from the blockchain
    const res = await this.apiClient.invoke<{ header: { height: number } }>("chain_getLastBlock", {});
    //[...]
}

Invoking via the node CLI

Any endpoint within the Lisk ecosystem can be invoked via node CLI as well. For more information, check out the v6@lisk-sdk::client-cli.adoc#endpoint.

If you are running Lisk Core, you can use mostly the same CLI commands as in the general node CLI. Just replace ./bin/run with lisk-core in that case.

To invoke an endpoint via node CLI, simply use the endpoint:invoke command as shown below:

$./bin/run endpoint:invoke chain_getLastBlock --pretty
{
  "header": {
    "version": 2,
    "timestamp": 1662742534,
    "height": 110,
    "previousBlockID": "4ef1095d3560064dd4a66fb4543680efe65a64020c363571b107be9513628674",
    "stateRoot": "b2507620beb3be5cd7d0cbb7926e4365b5674b682673dc2423400a497636e13e",
    "assetRoot": "2aa695e23b36439b56130a490ef38feaaec57d82859ff64f5ca61cc49993afa3",
    "eventRoot": "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855",
    "transactionRoot": "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855",
    "validatorsHash": "84f3ed67cec1eb7bd6dc3ec01b0d0323021c1e86a3dc760b9b92041c28da31ac",
    "aggregateCommit": {
      "height": 0,
      "aggregationBits": "",
      "certificateSignature": ""
    },
    "generatorAddress": "lsk5y2q2tn35xrnpdc4oag8sa3ktdacmdcahvwqot",
    "maxHeightPrevoted": 0,
    "maxHeightGenerated": 110,
    "signature": "6ecd5c6f14d18f84a2125cca4186a6cc493dcd66338f9b13c580cc06be7a33267fe259a074d6f6dc9276aff700a985472fca15cbcf25b2fde1b621fe0810b507",
    "id": "334416bdc1f8a7ff842728ac4e591337a0e7b80f190934694cad7e2a9afdb416"
  },
  "transactions": [],
  "assets": [
    {
      "module": "random",
      "data": "0a10dde856a212ac5af46e26abb5f941cc8b"
    }
  ]
}