@wmfs/statebox
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Orchestrate Node functions using Amazon States Language
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> Orchestrate Node functions using [Amazon States Language](https://states-language.net/spec.html)
## Useful links
* [AWS Step Functions](https://aws.amazon.com/step-functions/) - overview of Amazon States Language, use cases, etc
* [statelint](https://npmjs.com/package/@wmfs/statelint) - a validator for Amazon States Language JSON files
* https://docs.aws.amazon.com/step-functions/latest/dg/concepts-amazon-states-language.html
* https://docs.aws.amazon.com/step-functions/latest/apireference/API_SendTaskSuccess.html
## <a name='install'></a>Install
```bash
$ npm install @wmfs/statebox --save
```
## <a name='usage'></a>Usage
```javascript
const Statebox = require('@wmfs/statebox')
const statebox = new Statebox({})
const main = async
function() {
// STEP 1:
// Create some 'module' resources (i.e. Javascript
// classes with 'run' and optional 'init' methods)
// that state machines can then refer to...
// -------------------------------------------------
await statebox.ready
statebox.createModuleResources({
// Simple module to add two numbers together
add: class Add {
run(event, context) {
context.sendTaskSuccess(event.number1 + event.number2)
}
},
// Simple module to subtract one number from another
subtract: class Subtract {
// Init methods are optional, but all allow
// resource-instances to be configured...
init(resourceConfig, env, callback) {
callback(null)
}
run(event, context) {
context.sendTaskSuccess(event.number1 - event.number2)
}
}
})
// STEP 2:
// Next create a new 'calculator' state
// machine using Amazon States Language...
// ---------------------------------------
await statebox.createStateMachines({
'calculator': {
Comment: 'A simple calculator',
StartAt: 'OperatorChoice',
States: {
OperatorChoice: {
Type: 'Choice',
Choices: [{
Variable: '$.operator',
StringEquals: '+',
Next: 'Add'
}, {
Variable: '$.operator',
StringEquals: '-',
Next: 'Subtract'
}]
},
Add: {
Type: 'Task',
InputPath: '$.numbers',
Resource: 'module:add', // See createModuleResources()
ResultPath: '$.result',
End: true
},
Subtract: {
Type: 'Task',
InputPath: '$.numbers',
Resource: 'module:subtract',
ResultPath: '$.result',
End: true
}
}
}
}, {}, // 'env': An environment/context/sandbox
)
// STEP 3:
// Start a new execution on a state machine
// ----------------------------------------
const executionDescription = await statebox.startExecution({
numbers: {
number1: 3,
number2: 2
},
operator: '-'
}, // input
'calculator', // state machine name
{} // options
)
// STEP 4:
// Look at the results...
// ----------------------
console.log(executionDescription)
// Result object
// -------------
// {
// executionName: '...',
// ctx: {
// numbers': {
// number1: 3,
// number2: 2
// },
// operator: '-',
// result: 1 <--- The important bit :-)
// },
// currentStateName:'Subtract',
// currentResource:'module:subtract',
// stateMachineName:'calculator',
// startDate: '2018-09-03T21:58:04.287Z'
// }
}
if (require.main === module) {
main();
}
```
## <a name='test'></a>Testing
```bash
$ npm test
```
## <a name='license'></a>License
[MIT](https://github.com/wmfs/tymly/packages/statebox/blob/master/LICENSE)