event module

Nuls is a global blockchain open-source project which is a highly customizable modular blockchain infrastructure.

Event module is another module that can be added to Nuls Blockchain.

Module Features

• Event module publishes events (ex: new block, token transfer etc) which occur on Nuls Blockchain
• This module can be plugged into existing Nuls BlockChain
• Module can be bootstrapped like other modules
• Any subscriber can subscribe to these events and can be used according to their requirement

Technical Details

• Java 8
• Spring boot and web sockets
• Spring Boot supports web sockets implementation using STOMP protocol and sock JS.
• Spring scheduler to schedule the tasks required to get events from Nuls Blockcain
• Events are published as JSON string, client can consume JSON with their own implementation
• Sample Client code is available in repository - Sample Client app

Event Subscriptions

 Supported events as of now..  
  1. To subscribe to new block:  /block/latest
  2. To subscribe to token receive event(including NRC20 tokens) :  /tx/receiveToken/<your Nuls Address>
  3. To subscribe to consensus reward:      /tx/receiveReward/<your Nuls address>
  4. To subscribe to YELLOW cards for your node:  /agent/yellowCard/<agent_address>
  5. To subscribe to RED cards for your node: /agent/redCard/<agent_address>

Running the module

• Module can be integrated to existing Nuls modules
• When Nuls node or wallet is started, automatically event module will be started and subscription end points are open for clients

• Run module independently

```
git clone https://github.com/naveen7252/event-module.git
cd event-module
mvn clean install
cd base/event-base
mvn spring-boot:run
```

Client - How to subscribe to events

• Need following JS files

  • sock js client
    <script src="https://cdn.jsdelivr.net/npm/sockjs-client@1/dist/sockjs.min.js"></script> for more information , see "SockJS-Client"
  • stomp js library for more information, see "Stomp-JS"

• Connect to web socket at

     http://<hostname>:<port>/nulsWSocket
  

• subscribe to interested events

    Supported events as of now..  
          1. To subscribe to new block:  /block/latest
          2. To subscribe to token receive event(including NRC20 tokens) :  /tx/receiveToken/<your Nuls Address>
          3. To subscribe to consensus reward:      /tx/receiveReward/<your Nuls address>
          4. To subscribe to YELLOW cards for your node:  /agent/yellowCard/<agent_address>
          5. To subscribe to RED cards for your node: /agent/redCard/<agent_address>
  

• Refer to sample client application code repository - Sample Client app