Creating an endpoint & Testing the plugin

Now that we have our core logic in place, it is time to create an endpoint for the HelloInfoPlugin. The endpoint will fetch all the NewHello messages, sender addresses, and corresponding height of the block for each event, as stored in the database.

On this page, you’ll learn:

  • Creating an endpoint for the plugin.

  • Testing the plugin.

The relevant files discussed in this guide are endpoint.ts and hello_info_plugin.ts.

1. Creating an Endpoint

The endpoints of a plugin exist in an endpoint.ts file. So, let’s create an endpoint.ts file in the hello_info directory.

This file will contain the Endpoint class and an endpoint getMessageList().

The Endpoint class is based on the BasePluginEndpoint class, which is available in the klayr-sdk package.

hello_client/src/app/plugins/hello_info/endpoint.ts
import {
    Plugins,
    Types,
    db as klayrDB,
    cryptography,
} from 'klayr-sdk';
import {
    getEventHelloInfo,
} from './db';

export class Endpoint extends Plugins.BasePluginEndpoint {
    private _pluginDB!: klayrDB.Database;

    // Initialize the database instance here
    public init(db: klayrDB.Database) {
        this._pluginDB = db;
    }

    // [...]
}

Since the events data exists on an off-chain database, we must have an instance of the plugin’s database inside the Endpoint class.

The way to do that is to create an instance of the Endpoint class inside the HelloInfoPlugin class and pass the database instance to the endpoint.init() method in the load() function.

hello_client/src/app/plugins/hello_info/endpoint.ts
// [...]
import { Endpoint } from './endpoint';

export class HelloInfoPlugin extends Plugins.BasePlugin<HelloInfoPluginConfig> {
	// [...]

    public endpoint = new Endpoint();

    // [...]

    // loads DB instance and initiates endpoint.
	public async load(): Promise<void> {
		// [...]

		this.endpoint.init(this._pluginDB);

		// [...]
	}

    // [...]
}

Next up is the endpoint function, every public function present in the Endpoint class gets registered to the blockchain client. Since the endpoint will return a list of all the hello messages, we call it getMessageList().

The getMessageList() will have a messageList and a data[] which will contain the information retrieved from the database.

hello_client/src/app/plugins/hello_info/endpoint.ts
export class Endpoint extends Plugins.BasePluginEndpoint {
    // [...]

    // Returns all Sender Addresses, Hello Messages, and Block Height of the block where the Hello Event was emitted.
    public async getMessageList(_context: Types.PluginEndpointContext): Promise<unknown[]> {
        const data: {
            ID: number;
            senderAddress: string;
            message: string;
            blockHeight;
        }[] = [];
        // 1. Get all the stored events from the database.
        const messageList = await getEventHelloInfo(this._pluginDB);
        // 2. Push them into an array for presentation.
        for (const helloMessage of messageList) {
            data.push({
                ID: helloMessage.id.readUInt32BE(0),
                senderAddress: cryptography.address.getKlayr32AddressFromAddress(helloMessage['senderAddress']),
                message: helloMessage['message'],
                blockHeight: helloMessage['height'],
            })
        }
        return data;
    }
}

The getEventHelloInfo() will return all the newHello events stored inside the database. Once received, the endpoint will push each event’s data into an array of objects and will return this array as a response.

It is worth mentioning that an endpoint can also have various input arguments. These arguments are passed via the PluginEndpointContext class available in klayr-sdk. If the endpoint doesn’t require any arguments then, the request "params": {} property can be left empty. The arguments passed can be accessed via _context.ARGUMENT_EXAMPLE, etc.

2. Testing HelloInfoPlugin

Our implementation of HelloInfoPlugin is complete and it is time to test it out. Create and send a hello message as described in How to create a command → Try the new command out.

Once a transaction is verified and becomes part of the block, wait for your plugin’s sync interval to kick in. In our case, since we set the syncInterval configuration to 30 seconds (60000 milliseconds) in the custom_config.json, the sync will happen after every 30 seconds.

  1. If you started your node for the first time, you’ll see that the plugin instantiates the height in the database as shown in the following message:

    ** Height saved successfully in the database **

  2. After that, you should see that the plugin will set the initial value for the counter as well.

    ** Counter saved successfully in the database **

  3. The _syncChainEvents() will then store the event, update the counter, and set the height of the block where it found an event.

    ** Event Data saved successfully in the database **
** Counter saved successfully in the database **
** Height saved successfully in the database **

  4. At the end of the loop, the _syncChainEvents() will again update the height as per the last checked block height.

    ** Height saved successfully in the database **

After the first initiation, the plugin will repeat step 3 in each sync interval if it finds a newHello event(s) to store.

2.1. Querying Saved Events

The former log messages suggest that the plugin has stored a few events in its database, so let’s query them. While the client is running, let’s make an RPC request to the helloInfo_getMessageList endpoint.

./bin/run endpoint:invoke helloInfo_getMessageList --pretty

When the request is successful, the node will reply with something similar to the following:

[
    {
        "ID": 1,
        "senderAddress": "klyo5v2u2wjswjogxgxdr79c45kewprypouyaky76",
        "message": "Hello from Klayr.",
        "blockHeight": 22
    },
    {
        "ID": 2,
        "senderAddress": "klyo5v2u2wjswjogxgxdr79c45kewprypouyaky76",
        "message": "Hello from Lightcurve.",
        "blockHeight": 54
    }
]