Create Client-Side Auth with Finite State Machines, Redux and Redux Sagas

Arguably my favorite aspect of software engineering is that there is always room for new ideas. You don’t need any one persons permission to try something new, you just do it. Sometimes your new ideas work surprisingly well and sometimes they don’t but that’s the fun in trying something new.

The “new” idea I’d like to discuss in this article is using a Finite State Machine in combination with Redux and Redux-Saga to handle client-side authentication in your React app. The reason I put quotation marks around the word new is because individually each of these concepts have been around for quite some time. However, putting them all together to handle client-side authentication is, as far as I can tell, a new idea.

This article will be divided up into 6 parts:

  1. What are we going to be building?
  2. What are state machines?
  3. What are sagas?
  4. Basic app setup.
  5. Building the authentication architecture.
  6. Building the authentication user interface.

What We’re Building

Before you continue reading I think it’s important for you to know what exactly we’re building and determine whether or not you’re even interested in following along. The end goal of this article is to have a simple React app that implements authentication using a finite state machine that is connected to redux and uses redux-sagas as a separate thread for handling asynchronous actions (API calls).

There will be no focus on CSS, HTML or styling of any kind. The HTML will be kept as minimal as possible because the focus of this article is on the authentication architecture not on the user interface. At the end of this article you will have an app that allows a user to login, setup their account and logout. You will be able to take the ideas introduced in this article, expand on them and apply them to your applications.

#react #react-hook #redux

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Create Client-Side Auth with Finite State Machines, Redux and Redux Sagas

Create Client-Side Auth with Finite State Machines, Redux and Redux Sagas

Arguably my favorite aspect of software engineering is that there is always room for new ideas. You don’t need any one persons permission to try something new, you just do it. Sometimes your new ideas work surprisingly well and sometimes they don’t but that’s the fun in trying something new.

The “new” idea I’d like to discuss in this article is using a Finite State Machine in combination with Redux and Redux-Saga to handle client-side authentication in your React app. The reason I put quotation marks around the word new is because individually each of these concepts have been around for quite some time. However, putting them all together to handle client-side authentication is, as far as I can tell, a new idea.

This article will be divided up into 6 parts:

  1. What are we going to be building?
  2. What are state machines?
  3. What are sagas?
  4. Basic app setup.
  5. Building the authentication architecture.
  6. Building the authentication user interface.

What We’re Building

Before you continue reading I think it’s important for you to know what exactly we’re building and determine whether or not you’re even interested in following along. The end goal of this article is to have a simple React app that implements authentication using a finite state machine that is connected to redux and uses redux-sagas as a separate thread for handling asynchronous actions (API calls).

There will be no focus on CSS, HTML or styling of any kind. The HTML will be kept as minimal as possible because the focus of this article is on the authentication architecture not on the user interface. At the end of this article you will have an app that allows a user to login, setup their account and logout. You will be able to take the ideas introduced in this article, expand on them and apply them to your applications.

#react #react-hook #redux

Sidney  Purdy

Sidney Purdy

1592305339

Channels in Redux-saga

What are the channels? Are they useful to us in day to day programming? We’ll be going through this blog that channels are played really a major role in redux-saga.

Channels:
Channels are of 3 types which are used to perform 3 different things, here I will brief you about those channels here but will explain in detail a bit later.

  • Action Channels: Action channel is a buffer, it stockpiles actions which sagas can consume one by one.
  • Generic Channels: Generally, we use Generic channels to communicate between two sagas. This can be done through the Actions but the idea of a channel is that communication is limited interest in sagas without other sagas being privy to that information.
  • Event Channels: Event Channel is completely different used to wrap outside event sources. we can consider web socket as a good example of the Event channel.

#react #redux #saga #redux-saga

Easily Create A Finite State Machine and Define Legal State Transition

Dart State Machine

Easily create a finite state machine and define legal state transitions. Listen to state entrances, departures, and transitions.

Getting Started

Import the state_machine package:

import 'package:state_machine/state_machine.dart';

Create a Machine

Once created, the StateMachine will be used to create states and state transitions.

StateMachine light = new StateMachine('light');

Define a Set of States

Use the machine to create all required states. A string name is required for ease of debugging.

State isOn = light.newState('on');
State isOff = light.newState('off');

It's recommended that states be named in the format "is[State]". This may seem strange at first, but it has two main benefits:

  1. It helps differentiate states from transitions, which can be confusing since many words in English are the same as a verb and an adjective ("open" or "secure", for example).
  2. It reads better when calling the state to determine if it's active, as will be demonstrated later.

Define the Legal State Transitions

By defining legal state transitions, you can prevent certain actions based on the current state of the machine. Defining a state transition requires a name (again for ease of debugging), a list of valid "from" states, and the state to transition the machine to.

StateTransition turnOn = light.newStateTransition('turnOn', [isOff], isOn);
StateTransition turnOff = light.newStateTransition('turnOff', [isOn], isOff);

Start the Machine

Before executing any state transitions, the machine should be started at a specific starting state.

light.start(isOff);

Executing a State Transition

The StateTransition class implements Function so that you can simply call a transition to execute it.

light.start(isOff);
turnOn(); // transitions machine from "isOff" to "isOn"

Determining the Active State

The StateMachine instance exposes a current state property which allows you to retrieve the machine's current state at any time.

light.start(isOff);
light.current == isOff; // true

Additionally, the State class implements Function so that you can simply call a state to determine if it's active.

light.start(isOff);
isOff(); // true
isOn();  // false

Listening to State Transitions

The StateTransition class exposes a listen() method that allows you to listen to the transition and receive an event every time the transition executes.

turnOn.listen((StateChange change) {
  print('Light transitioned from ${change.from.name} to ${change.to.name}');
});
light.start(isOff);
turnOn(); // "Light transitioned from off to on"

Passing Data with a State Transition

State transitions accept an optional payload in case you need to pass data along to listeners.

turnOn.listen((StateChange change) {
  print('Light turned on. Wattage: ${change.payload}');
});
light.start(isOff);
turnOn('15w'); // "Light turned on. Wattage: 15w"

Listening for State Entrances and Departures

The State class exposes two streams so that you can listen for the state being entered and the state being left.

isOff.onLeave.listen((StateChange change) {
  print('Left: off');
});
isOn.onEnter.listen((StateChange change) {
  print('Entered: on');
});
light.start(isOff);
turnOn(); // "Left: off"
          // "Entered: on"

Wildcard State and State Transitions

The State class exposes a static instance State.any that can be used as a wildcard when defining a state transition.

StateMachine machine = new StateMachine('machine');
State isFailed = machine.newState('failed');

// This transition will be valid regardless of which state the machine is in.
StateTransition fail = machine.newStateTransition('fail', [State.any], isFailed);

Illegal State Transitions

When you create state transitions, you must define the list of valid "from" states. The machine must be in one of these states in order to execute the transition. If that's not the case, an IllegalStateTransition exception will be thrown.

// Consider a door with the following states and transitions.
StateMachine door = new StateMachine('door');

State isOpen = door.newState('open');
State isClosed = door.newState('closed');
State isLocked = door.newState('locked');

StateTransition open = door.newStateTransition('open', [isClosed], isOpen);
StateTransition close = door.newStateTransition('close', [isOpen], isClosed);
StateTransition lock = door.newStateTransition('lock', [isClosed], isLocked);
StateTransition unlock = door.newStateTransition('unlock', [isLocked], isClosed);

// Let's transition the door from open, to closed, to locked.
door.start(isOpen);
close();
lock();

// In order to open the door, we must first unlock it.
// If we try to open it first, an exception will be thrown.
open(); // throws IllegalStateTransition

Canceling State Transitions

State machines have a set of legal state transitions that are set in stone and provide the required structure. But, there may be scenarios where a state transition may or may not be desirable based on additional logic. To handle this, state transitions support cancellation conditions.

// Consider two state machines - a person and a door.
// The door can be locked or unlocked and the person
// can be with or without a key.
StateMachine door = new StateMachine('door');
State isLocked = door.newState('locked');
State isUnlocked = door.newState('unlocked');
StateTransition unlock = door.newStateTransition('unlock', [isLocked], isUnlocked);

StateMachine person = new StateMachine('person');
State isWithKey = person.newState('withKey');
State isWithoutKey = person.newState('withoutKey');
StateTransition obtainKey = person.newStateTransition('obtainKey', [isWithoutKey], isWithKey);

door.start(isLocked);
person.start(isWithoutKey);

// Add a cancellation condition for unlocking the door:
// If the person is without a key, cancel the unlock transition.
unlock.cancelIf((StateChange change) => isWithoutKey());

unlock(); // false (canceled)
isUnlocked(); // false
obtainKey();
unlock(); // true (not canceled)
isUnlocked(); // true

Development

This project leverages the dart_dev package for most of its tooling needs, including static analysis, code formatting, running tests, collecting coverage, and serving examples. Check out the dart_dev readme for more information.

Use this package as a library

Depend on it

Run this command:

With Dart:

 $ dart pub add state_machine

With Flutter:

 $ flutter pub add state_machine

This will add a line like this to your package's pubspec.yaml (and run an implicit dart pub get):

dependencies:
  state_machine: ^2.2.2

Alternatively, your editor might support dart pub get or flutter pub get. Check the docs for your editor to learn more.

Import it

Now in your Dart code, you can use:

import 'package:state_machine/state_machine.dart'; 

Download Details:

Author: Workiva

Source Code: https://github.com/Workiva/state_machine

#dart #state #machine 

Sidney  Purdy

Sidney Purdy

1589784411

Create your Saga with Redux-Saga

After reading this blog, you will be able to understand the brief about what is redux-saga. Also you able to install, configure, and create the basic saga in your application. So, before we get any deeper, it’s important to note, that the actual term “saga”.

A saga in general programming series of reversible transactions, the saga is designed to replace single huge, locking transactions.

eg: Deposit in a bank would require a change in different spreadsheets, the traditional way requires locking all these spreadsheets changing a value then unlocking them

Whereas in functional programming, in the saga, you can break the transactions into small steps, and if there was any error along the way you can reverse all the steps that you’ve taken. Now, to manage all this, saga uses a process manager to keep track of what’s been done and what other actions need to be taken.

What is Redux-Saga?
Redux-saga is a redux middleware library, that is designed to handle side effects in your redux app nice and simple. It achieves this by leveraging an ES6 feature called Generators, allowing us to write asynchronous code that looks synchronous, and is very easy to test.

#react #reactjs #saga #redux #reduxsaga

sophia tondon

sophia tondon

1620898103

5 Latest Technology Trends of Machine Learning for 2021

Check out the 5 latest technologies of machine learning trends to boost business growth in 2021 by considering the best version of digital development tools. It is the right time to accelerate user experience by bringing advancement in their lifestyle.

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Visit Blog- https://www.xplace.com/article/8743

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