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Almin: Flux/CQRS patterns for JavaScript applications

website·Indexed 31 days ago

https://almin.js.org/

A state management library for JavaScript applications that implements Flux and Command Query Responsibility Segregation (CQRS) patterns. It provides core components including Dispatcher, Context, UseCase, and Store, with built-in support for TypeScript and performance profiling in versions 1.4.0+.

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What's inside Almin

  1. Overview of AlminFlux CQRS State Management

    AlminFlux is a state management library for JavaScript applications that implements CQRS (Command Query Responsibility Segregation) and DDD (Domain-Driven Design) patterns. It is designed to be scalable for projects ranging from 1,000 to 100,000 lines of code. The library focuses on the application layer, allowing developers to write domain logic in pure JavaScript without requiring the domain to be a subclass of Almin components. This ensures that the domain logic remains portable and does not need to be rewritten if the state management library is changed.

  2. Overview of Almin features and architecture

    Almin is a library (not a framework) that provides Flux and CQRS (Command Query Responsibility Segregation) patterns for JavaScript applications. It is designed to support layered architectures, including Domain-Driven Design (DDD), and is compatible with TypeScript and Flow. Key characteristics include scalability (from 1,000 to 100,000 lines of code), testability through separated UseCase, Store, and Domain components, and debuggability via dedicated logging and performance monitoring tools.

  3. Overview of almin architectural components

    The almin framework is built around several core architectural concepts for managing domain logic and state:

    • UseCase: Serves as the entry point to the domain model.
    • Domain: Contains the business logic of the application.
    • Store: Manages state and can implement patterns similar to Redux reducers.
    • StoreGroup: Used to handle and coordinate multiple Stores.
    • Context: Acts as the central communicator between Stores and UseCases.

  4. Overview of almin-logger capabilities

    almin-logger is a logging library designed for the almin framework. It provides the following core features:

    • Logging the execution of UseCases
    • Logging changes occurring within a Store
    • Support for nested logging (utilizing console.groupCollapsed if supported by the browser)
    • Asynchronous logging support

  5. Overview of AlminFlux state management

    AlminFlux is a state management library for JavaScript applications designed to support scalable, testable, and debuggable architectures. It focuses on separating the domain logic from the application layer, allowing developers to write their domain in pure JavaScript without inheriting from Almin-specific classes. This ensures that the domain logic remains portable and does not need to be rewritten if the state management library is changed.

    Key architectural principles include:

    • CQRS (Command Query Responsibility Segregation): Splitting the 'Read stack' and 'Write stack'.
    • Unidirectional Data Flow: Ensuring predictable state transitions.
    • Layered Architecture: Compatibility with Domain-Driven Design (DDD) and CQRS.
    • Observability: Built-in support for logging, performance monitoring, and DevTools.

  6. Manage state with Store and StoreGroup

    Almin uses Stores to manage state objects. Stores are observable, allowing Views to observe them and update the UI automatically when the state changes.

    A StoreGroup is a collection of stores that wraps them to behave as a single Store entity.

  7. Use the Dispatcher central event bus

    The Dispatcher class is the central event bus system in Almin. It allows components to communicate by dispatching and subscribing to payload objects. Unlike standard event emitters that use emit(key, ...args), Almin uses a single payload object to avoid repeated casting when passing data between different dispatchers.
    import { Dispatcher } from 'almin';

const dispatcher = new Dispatcher();

  8. Implement Unidirectional Data Flow in Almin

    Almin follows a unidirectional data flow architecture to ensure predictable state updates. The flow of data and actions is as follows:

    UseCase $ ightarrow$ Domain $ ightarrow$ Repository $ ightarrow$ Store $ ightarrow$ (New State) $ ightarrow$ View

    In this flow, the View observes the Store via the Almin Context. When the Store state changes, the View is automatically updated.

  9. Understand Almin's CQRS Architecture

    Almin implements the CQRS (Command Query Responsibility Segregation) pattern by splitting the conceptual model into two stacks:

    1. Write Stack (Command Model): Contains the business logic and the Domain Model. This is where data is validated and modified.
    2. Read Stack (Query Model): Similar to a ViewModel and Store, providing data optimized for the view.

    Key architectural distinctions:

    • Domain Layer: POJOs containing business logic.
    • Infra Layer: Repositories for persistent data.
    • Store: Used for data specifically intended for the view.

  10. React Native compatibility in Almin 0.18

    Almin 0.18 removes the dependency on the Node.js events module. This ensures compatibility with React Native (where the Node.js Core API events module is not bundled by default) and reduces the overall file size.

  11. Apply CQRS principles in Almin

    Almin incorporates CQRS (Command Query Responsibility Segregation), which splits the conceptual model into two separate models: a Command (Write) model and a Query (Read) model.

  12. Monitor UseCase execution with lifecycle handlers

    The LifeCycleEventHub provides several methods to track the execution flow of UseCases:

    • onWillExecuteEachUseCase: Called when a UseCase is about to execute.
    • onWillNotExecuteEachUseCase: Called when a UseCase will not execute (e.g., UseCase#shouldExecute returned false).
    • onDidExecuteEachUseCase: Called when UseCases have been executed.
    • onCompleteEachUseCase: Called when UseCases are completed. This handler is always called asynchronously.