# <img src="https://uploads-ssl.webflow.com/5ea5d3315186cf5ec60c3ee4/5edf1c94ce4c859f2b188094_logo.svg" alt="Pip.Services Logo" width="200"> <br/> Portable Component Model for Node.js

This module is a part of the [Pip.Services](http://pip.services.org) polyglot microservices toolkit.

It defines a portable component model interfaces and provides utility classes to handle component lifecycle.

The module contains the following packages:
- **Build** - basic factories for constructing objects
- **Config** - configuration pattern
- **Refer** - locator inversion of control (IoC) pattern
- **Run** - component life-cycle management patterns

<a name="links"></a> Quick links:

* [Configuration Pattern](http://docs.pipservices.org/toolkit/getting_started/configurations/) 
* [Locator Pattern](http://docs.pipservices.org/toolkit/recipes/component_references/)
* [Component Lifecycle](http://docs.pipservices.org/toolkit/recipes/component_lifecycle/)
* [API Reference](https://pip-services4-node.github.io/pip-services4-components-node/globals.html)
* [Change Log](CHANGELOG.md)
* [Get Help](http://docs.pipservices.org/get_help/)
* [Contribute](http://docs.pipservices.org/contribute/)

## Use

Install the NPM package as
```bash
npm install pip-services4-components-node --save
```

Then you are ready to start using the Pip.Services patterns to augment your backend code.

For instance, here is how you can implement a component, that receives configuration, get assigned references,
can be opened and closed using the patterns from this module.

```typescript
import { IConfigurable } from 'pip-services4-components-node';
import { ConfigParams } from 'pip-services4-components-node';
import { IReferenceable } from 'pip-services4-components-node';
import { IReferences } from 'pip-services4-components-node';
import { Descriptor } from 'pip-services4-components-node';
import { IOpenable } from 'pip-services4-components-node';

export class MyComponentA implements IConfigurable, IReferenceable, IOpenable {
    private _param1: string = "ABC";
    private _param2: number = 123;
    private _anotherComponent: MyComponentB;
    private _opened: boolean = true;

    public configure(config: ConfigParams): void {
        this._param1 = config.getAsStringWithDefault("param1", this._param1);
        this._param2 = config.getAsIntegerWithDefault("param2", this._param2);
    }

    public setReferences(refs: IReferences): void {
        this._anotherComponent = refs.getOneRequired<MyComponentB>(
            new Descriptor("myservice", "mycomponent-b", "*", "*", "1.0")
        );
    }

    public isOpen(): boolean {
        return this._opened;
    }

    public open(context: IContext, callback: (err: any) => void): void {
        this._opened = true;
        console.log("MyComponentA has been opened.");
        callback(null);
    }

    public close(context: IContext, callback: (err: any) => void): void {
        this._opened = true;
        console.log("MyComponentA has been closed.");
        callback(null);
    }

}
```

Then here is how the component can be used in the code

```typescript
import { ConfigParams } from 'pip-services4-components-node';
import { References } from 'pip-services4-components-node';
import { Descriptor } from 'pip-services4-components-node';

let myComponentA = new MyComponentA();

// Configure the component
myComponentA.configure(ConfigParams.fromTuples(
  'param1', 'XYZ',
  'param2', 987
));

// Set references to the component
myComponentA.setReferences(References.fromTuples(
  new Descriptor("myservice", "mycomponent-b", "default", "default", "1.0",) myComponentB
));

// Open the component
myComponentA.open("123", (err) => {
   console.log("MyComponentA has been opened.");
   ...
});
```

If you need to create components using their locators (descriptors) implement 
component factories similar to the example below.

```typescript
import { Factory } from 'pip-services4-components-node';
import { Descriptor } from 'pip-services4-components-node';

export class MyFactory extends Factory {
  public static myComponentDescriptor: Descriptor = new Descriptor("myservice", "mycomponent", "default", "*", "1.0");
  
  public MyFactory() {
    super();
    
    this.registerAsType(MyFactory.myComponentDescriptor, MyComponent);    
  }
}

// Using the factory

let myFactory = MyFactory();

let myComponent1 = myFactory.create(new Descriptor("myservice", "mycomponent", "default", "myComponent1", "1.0");
let myComponent2 = myFactory.create(new Descriptor("myservice", "mycomponent", "default", "myComponent2", "1.0");

...
```

## Develop

For development you shall install the following prerequisites:
* Node.js 14+
* Visual Studio Code or another IDE of your choice
* Docker
* Typescript

Install dependencies:
```bash
npm install
```

Compile the code:
```bash
tsc
```

Run automated tests:
```bash
npm test
```

Generate API documentation:
```bash
./docgen.ps1
```

Before committing changes run dockerized build and test as:
```bash
./build.ps1
./test.ps1
./clear.ps1
```

## Contacts

The module is created and maintained by **Sergey Seroukhov** and **Danil Prisyazhniy**.

The documentation is written by:
- **Egor Nuzhnykh**
- **Alexey Dvoykin**
- **Mark Makarychev**
- **Eugenio Andrieu**