@burstjs/monitor
A monitor to watch for specific changes on the Burst blockchain
Due to average blocktime of 240 seconds, transactions stay pending for a certain time. It is a repeating pattern to watch for such changes and waiting for confirmation. This package simplifies this task.
As additional feature, a monitor is serializable, that means it can be stored e restored. This is especially useful for web applications, as it allows reloading pages without losing the ability to check whether a transaction is still pending or already concluded.
Installation
@burstjs/monitor can be used with NodeJS or Web. Two formats are available
Using with NodeJS and/or modern web frameworks
Install using npm:
npm install @burstjs/monitor
or using yarn:
yarn add @burstjs/monitor
Example
import {Monitor} from '@burstjs/monitor'
import {composeApi} from "@burstjs/core";
// A method that checks if an account exists
// > IMPORTANT: Do not use closures, when you need to serialize the monitor
async function tryFetchAccount() {
const BurstApi = composeApi({ nodeHost: 'https://testnet.burstcoin.network:6876/'})
try{
const {account} = await BurstApi.account.getAccount('1234')
return account;
}catch (e){
// ignore error
return null;
}
}
// A comparing function to check if a certain condition for the returned data from fetch function
// is true. If it's true the monitor stops
function checkIfAccountExists(account) {
return account !== null;
}
// Create your monitor
const monitor = new Monitor({
asyncFetcherFn: tryFetchAccount,
compareFn: checkIfAccountExists,
intervalSecs: 10, // polling interval in seconds
key: 'monitor-account',
timeoutSecs: 2 * 240 // when reached timeout the monitor stops
});
// starts monitor
monitor.start();
// called when `checkIfAccountExists` returns true
monitor.onFulfilled(() => {
console.log('Yay, account active');
});
// called when `timeoutSecs` is reached
monitor.onTimeout(() => {
console.log('Hmm, something went wrong');
});
Using in classic <script>
Each package is available as bundled standalone library using IIFE.
This way burstJS can be used also within <script>-Tags.
This might be useful for Wordpress and/or other PHP applications.
Just import the package using the HTML <script> tag.
<script src='https://cdn.jsdelivr.net/npm/@burstjs/monitor/dist/burstjs.monitor.min.js'></script>
Example
const monitor = new b$monitor.Monitor({
//...
});
monitor.start()
monitor.onFulFilled(() => {
//...
})Monitor Serialization
TO DO
See more here:
@burstjs/monitor Online Documentation
API Reference
monitor
The generic monitor class.
A monitor can be used to check periodically for a certain situation, e.g. confirmation of a transaction, activation on an account, or even something completely different.
Example: (checking for the existence of an account aka account activation)
// A method that checks if an account exists
// > IMPORTANT: Do not use closures, when you need to serialize the monitor
async function tryFetchAccount() {
const BurstApi = composeApi({ nodeHost: 'https://testnet.burstcoin.network:6876/'})
try{
const {account} = await BurstApi.account.getAccount('1234')
return account;
}catch (e){
// ignore error
return null;
}
}
// A comparing function to check if a certain condition for the returned data from fetch function
// is true. If it's true the monitor stops
function checkIfAccountExists(account) {
return account !== null;
}
// Create your monitor
const monitor = new Monitor<Account>({
asyncFetcherFn: tryFetchAccount,
compareFn: checkIfAccountExists,
intervalSecs: 10, // polling interval in seconds
key: 'monitor-account',
timeoutSecs: 2 * 240 // when reached timeout the monitor stops
})
.onFulfilled(() => {
// called when checkIfAccountExists returns true
console.log('Yay, account active');
})
.onTimeout(() => {
// called when timeoutSecs is reached
console.log('Hmm, something went wrong');
}).start();
monitor~Monitor
Kind: inner class of monitor
new Monitor(args)
The monitors constructor
| Param | Description |
|---|---|
| args | The arguments |
monitor.startTime
The start timestamp if started, or -1
Kind: instance property of Monitor
monitor.intervalSecs
The interval
Kind: instance property of Monitor
monitor.key
The key aka identifier
Kind: instance property of Monitor
monitor.timeoutSecs
The timeout
Kind: instance property of Monitor
monitor.serialize()
Serializes the monitor, such it can be stored.
This serializes also the asyncFetcher and compareFn
It is important that these functions are not closures, i.e. the must not reference
outer data/variables, otherwise the behavior on deserialization is not deterministic
Kind: instance method of Monitor
monitor.hasStarted() ⇒
Kind: instance method of Monitor
Returns:
true, if monitor was started and is running
monitor.isExpired() ⇒
Kind: instance method of Monitor
Returns:
true, if a started monitor timed out.
monitor.start()
Starts the monitor
Kind: instance method of Monitor
monitor.stop()
Stops the monitor
Kind: instance method of Monitor
monitor.onTimeout(fn)
Callback function for timeout event. You can add multiple event listener if you want
Kind: instance method of Monitor
| Param | Description |
|---|---|
| fn | The callback |
monitor.onFulfilled(fn)
Callback function for fulfilled event. You can add multiple event listener if you want
Kind: instance method of Monitor
| Param | Description |
|---|---|
| fn | The callback |
Monitor.deserialize(serializedMonitor, autoStart) ⇒
Deserializes a serialized monitor
Kind: static method of Monitor
Returns:
The monitor instance
See:
[[Monitor.serialize]]
| Param | Default | Description |
|---|---|---|
| serializedMonitor | The serialized monitor |
|
| autoStart | true |
If monitor was started on serialization the monitor starts automatically, if set true (default) |