Book Image

Building Enterprise JavaScript Applications

By : Daniel Li
Book Image

Building Enterprise JavaScript Applications

By: Daniel Li

Overview of this book

With the over-abundance of tools in the JavaScript ecosystem, it's easy to feel lost. Build tools, package managers, loaders, bundlers, linters, compilers, transpilers, typecheckers - how do you make sense of it all? In this book, we will build a simple API and React application from scratch. We begin by setting up our development environment using Git, yarn, Babel, and ESLint. Then, we will use Express, Elasticsearch and JSON Web Tokens (JWTs) to build a stateless API service. For the front-end, we will use React, Redux, and Webpack. A central theme in the book is maintaining code quality. As such, we will enforce a Test-Driven Development (TDD) process using Selenium, Cucumber, Mocha, Sinon, and Istanbul. As we progress through the book, the focus will shift towards automation and infrastructure. You will learn to work with Continuous Integration (CI) servers like Jenkins, deploying services inside Docker containers, and run them on Kubernetes. By following this book, you would gain the skills needed to build robust, production-ready applications.
Table of Contents (26 chapters)
Title Page
Copyright and Credits
Packt Upsell
Free Chapter
The Importance of Good Code

High availability

Availability is a measure of the proportion of time that a system is able to fulfill its intended function. For an API, it means the percentage of time that the API can respond correctly to a client's requests.

Measuring availability

Availability is usually measured as the percentage of time the system is functional (Uptime) over the total elapsed time:

This is typically represented as "nines". For example, a system with an availability level of "four nines" will have an uptime of 99.99% or higher.

Following the industry standard

Generally speaking, the more complex a system, the more things can go wrong; this translates to a lower availability. In other words, it is much easier to have a 100% uptime for a static website than for an API.

So, what is the industry standard for availability for common APIs? Most online platforms offer a service level agreement (SLA) that includes a clause for the minimum availability of the platform. Here are some examples (accurate at the time...