#Creating a dApp Module

#Step 1: Prepare Your Local Development Environment

Many components are required to have a proper environment setup for the development of your ARK Core module. You can view instructions on how to setup your development environment here:

#Step 2: Create A New Module From A Template

github.com

GitHub - learn-ark/dapp-core-module-template at develop

A Basic Core dApp Module Application Template. Contribute to learn-ark/dapp-core-module-template development by creating an account on GitHub.

After your repository has been created, you can add it as a submodule within the core/plugins folder and start changing the defaults.

1cd plugins/
2git submodule add -f https://github.com/your-username/your-core-plugin-repo-name

#1.1 Module Configuration

We need to make some changes to the project first. Make sure to modify the default names for the files:

• package.json (model name, dependencies and other npm fields)
• src/defaults.ts (settings)
• src/index.ts (exports)
• src/service-provider.ts (registration logic)

The name of our module is @vendorname/your-dapp-name. Make sure to change the name in your package.json accordingly. It is recommended to scope your packages with a prefix like @your-vendor/ to distinguish it from other npm packages. Check https://docs.npmjs.com/misc/scope for more information.

#1.2 Adding Module Dependencies

If your package relies on any dependencies you should install them via lerna add the plugin you are developing.

1lerna add dependency-name --scope=@vendor/demo-plugin --dev

Once everything is set up and configured, we can move on to developing the plugin.

#Step 3: Module Registration Within Network Configuration

Since, we are running a local development environment, we will need to edit the Testnet configuration folder (core/packages/core/bin/config/testnet/app.json) and add our module name to the list of loaded modules. This is also a good place to set up the module’s default properties, defined in the default.ts file in our module’s root folder.

app.json

 1module.exports = {
 2    "core": {
 3        "plugins": [
 4            // Order is IMPORTANT!
 5            // Modules are loaded in the same order as they are listed
 6            {
 7                "package": "@arkecosystem/core-logger-pino"
 8            },
 9            {
10                "package": "@arkecosystem/core-state"
11            },
12            {
13                "package": "@arkecosystem/core-database"
14            },
15            {
16                "package": "@arkecosystem/core-transactions"
17            },
18            ...
19            ... // other core plugins and their settings
20            ...
21            {
22                "package": "@your-vendor/your-module-name-from-package",
23                "options": {
24                    // Here we can overwrite the module properties that are defined in defaults.ts file
25                    enabled: true,
26                    host: "0.0.0.0",
27                    port: 8081,
28                    ...
29                    ...
30                }
31            }
32        ]
33    }
34};

After yarn setup completes you should see the following output:

1lerna success - @arkecosystem/core-api
2lerna success - @arkecosystem/core-blockchain
3lerna success - @arkecosystem/core-cli
4lerna success - @arkecosystem/core-database
5lerna success - @arkecosystem/core-forger
6lerna success - @arkecosystem/core-kernel
7lerna success - @arkecosystem/core-logger-pino
8lerna success - @vendorname/dappname # Your Module

Every plugin that is being registered in this file will be automatically loaded one after another to guarantee that all required data is available, so make sure your custom modules are placed in the right spot.

#Step 4: Running Your dApp

Start local blockchain with Testnet running on your developer computer. Follow steps defined in here:

If you already have compiled and running core, just go to core/packages/core and run the yarn full:testnet command.

After the local Testnet starts, the log should show that dApp Module was loaded and run. Console output should look like this (if you haven’t changed the source code from the template):

1[2020-10-22 11:13:27.161] INFO : Loading dApp
2[2020-10-22 11:13:27.161] INFO : Booting of dApp

Feel free to look at other Core packages that expose important Core Platform building blocks to work with. Your newly developed classes can extend this class and gain access to:

• wallets and state
• transaction pool
• blockchain protocol
• events
• database
• api
• logger
• well…actually any core-module :)