Blocking and non-blocking software development

Let's go ahead and take a look at the differences between blocking and non blocking software development:

In the preceding screenshot, I have two files that we'll be executing. But before going to that, first let's explore how each of these files operates, the steps that are required in order to finish the program.

This will help us understand the big differences between blocking, which I have on the left side of the image, which is not what Node uses, and non-blocking is on the right side, which is exactly how all of our Node applications in the book are going to operate.

You don't have to understand the individual details, such as what require is, in order to understand what's going on in this code example. We'll be breaking things down in a very general sense. The first line on each code is responsible for fetching a function that gets called. This function will be our simulated I/O function that is going to a database, fetching some user data and printing it to the screen.

Refer to the preceding code image. After we load in the function, both files try to fetch a user with an ID of 123. When it gets that user, it prints it to the screen with the user1 string first, and then it goes on and it fetches the user with 321 as the ID. And it prints that to the screen. And finally both files add up 1 + 2, storing the result, which is 3, in the sum variable and print it to the screen.

Now, while they all do the same thing, they do it in very different ways. Let's break down the individual steps. In the following code image, we'll go over what Node executes and how long it takes:

You can consider the seconds shown in the preceding screenshot; it doesn't really matter, it's just to show the relative operating speed between the two files.