🔌 ServiceManager

What is the ServiceManager?

ServiceManager is probably the most basic implementation of dependency injection container for JavaScript.

Quick start

Execute npm install servicemanager or yarn add servicemanager to install servicemanager and its dependencies into your project directory.

Usage

Basics (Hooks Way)

To register objects to service manager, create a file/module for your service context:

//
// serviceContext.js
//
import { createContext, factory, singleton } from 'servicemanager';

const context = createContext(
    [ 'ResourceManager', factory(DefaultResourceManager) ],
    [ 'CacheManager', factory(CustomCacheManager) ],
    [ 'SessionManager', singleton(mySessionManager) ]
);

To get objects back from service manager:

//
// anotherFile.js
//
import useServiceManager from 'servicemanager';

// get default service context
const context = useServiceManager();

// returns a new instance for DefaultResourceManager
const resourceManager = context.get('ResourceManager');

// returns a new instance for CustomCacheManager
const cacheManager = context.get('CacheManager');

// returns the same session manager object that referenced by mySessionManager
const sessionManager = context.get('SessionManager');

Alternatively, to get all needed instances at once:

//
// anotherFile2.js
//
import useServiceManager from 'servicemanager';

// get default service context
const context = useServiceManager();

const [ resourceManager, cacheManager, sessionManager ] = context.getRange('ResourceManager', 'CacheManager', 'SessionManager');

...Or, to have them in more promise-friendly way:

//
// anotherFile3.js
//
import useServiceManager from 'servicemanager';

// get default service context
const context = useServiceManager();

context.ensure([ 'ResourceManager', 'CacheManager', 'SessionManager' ], (resourceManager, cacheManager, sessionManager) => {
    // awaits promisified generator functions first,
    // then services dependencies as parameters
});

*** Note: Service names can be anything including objects, symbols or strings.

Basics (Functional Way)

To register objects to service manager, create a file/module for your service context:

//
// serviceContext.js
//
import { createContext, factory, singleton } from 'servicemanager';

const context = createContext(
    [ 'ResourceManager', factory(DefaultResourceManager) ],
    [ 'CacheManager', factory(CustomCacheManager) ],
    [ 'SessionManager', singleton(mySessionManager) ]
);

export {
    context as default,
};

To get objects back from service manager:

//
// anotherFile.js
//
import { get } from 'servicemanager';
import context from './serviceContext.js';

// returns a new instance for DefaultResourceManager
const resourceManager = get(context, 'ResourceManager');

// returns a new instance for CustomCacheManager
const cacheManager = get(context, 'CacheManager');

// returns the same session manager object that referenced by mySessionManager
const sessionManager = get(context, 'SessionManager');

Alternatively, to get all needed instances at once:

//
// anotherFile2.js
//
import { getRange } from 'servicemanager';
import context from './serviceContext.js';

const [ resourceManager, cacheManager, sessionManager ] = getRange(context, 'ResourceManager', 'CacheManager', 'SessionManager');

...Or, to have them in more promise-friendly way:

//
// anotherFile3.js
//
import { ensure } from 'servicemanager';
import context from './serviceContext.js';

ensure(context, [ 'ResourceManager', 'CacheManager', 'SessionManager' ], (resourceManager, cacheManager, sessionManager) => {
    // awaits promisified generator functions first,
    // then services dependencies as parameters
});

*** Note: Service names can be anything including objects, symbols or strings.

API

ServiceContext.prototype methods

constructor(...definitions: ServiceDefinitions)

get(dependency: any): any

getRange(...dependencies: Array<any>): Array<any>

ensure(dependencies: Array<any>, callback: (...services: Array<any>) => any): Promise<any>

all(): Array<string>

filter(predicate: FilterPredicate): Array<string>

filterByTag(tag: string): Array<string>

Mechanics

Factory services call generator/dependency target each time they are requested, whereas, Singleton services are registered when they are defined.

import createContext, { factory, singleton } from 'servicemanager';

const date1 = Symbol('date1');
const date2 = Symbol('date2');

const context = createContext(
    [ date1, factory(() => new Date()) ],
    [ date2, singleton(new Date()) ]
);

console.log(context.get(date1)); // calls and returns new Date()
console.log(context.get(date1)); // calls and returns new Date() again,
console.log(context.get(date2)); // no calls, returns stored date.

Todo List

See GitHub Projects for more.

Requirements

• node.js (https://nodejs.org/)

License

Apache 2.0, for further details, please see LICENSE file

Contributing

See contributors.md

It is publicly open for any contribution. Bugfixes, new features and extra modules are welcome.

• To contribute to code: Fork the repo, push your changes to your fork, and submit a pull request.
• To report a bug: If something does not work, please report it using GitHub Issues.

To Support

Visit my patreon profile at patreon.com/eserozvataf