Non-Blocking I/O Operation with Spring WebFlux

Spring WebFlux is most powerful framework for building reactive, non-blocking web applications. Unlike the traditional Spring MVC which can be based on the synchronous, blocking the I/O model, Spring WebFlux the reactor library enables asynchronous and nonblocking operations. It can allow for better scalability and performance, especially under high load conditions, by efficiently utilizing system resources.

The main concept behind the non-blocking I/O in the Spring WebFlux is to handle the requests and responses asynchronously. This means that the processing of one request does not block the processing of the other requests. It can achieved through the use of reactive streams and publishers like mono and Flux which can represent the single and multiple asynchronous values, respectively.

Reactive Streams

Reactive streams are the specification for asynchronous stream processing with non-blocking back pressure. It can implement this specification using the Reactor library.

• Mono: It represents the single asynchronous value or an empty value.
• Flux: It represents the sequence of the asynchronous values.

These types enable the composing asynchronous, event-driven programs by the providing operators to transform, filter and combine the multiple asynchronous values.

Working of Non-Blocking I/O

In the non-blocking I/O model, threads are not tied up waiting for the I/O operations to complete. Instead, they can handle the other tasks while waiting for the I/O operations to finish. It can be particularly useful in the web applications, where the I/O operations such as the network calls and database access can be slow and frequent.

Key Terminologies:

• Reactive programming: The programming paradigm oriented data streams and the propagation of the change. It allows for the asynchronous data processing. Making it easier to build the non-blocking systems.
• Non-Blocking I/O: An I/O operation that does not block the execution thread while waiting for the operation to complete. It allows the other tasks to be performed concurrently.
• Reactive Streams: The standard for asynchronous stream processing with the non-blocking back pressure. It provides the common way to manage the streams of the data asynchronously.
• Back Pressure: A mechanism for handling the flow of the data between producers and consumers in the reactive programming to prevent the overwhelming the consumer with too much data at once.
• Publisher: The interface in the reactive streams that can be produces data and sends it to subscribers.
• Subscriber: The interface in the reactive streams that can be consumes data provided by the publishers.
• Asynchronous: The form of computation where operations are executed independently of the main program flow, allowing the programs to continue the running while waiting for the operations to complete.

Implementation of Non-Blocking I/O Operation with Spring WebFlux

Below are the implementation steps of Non-Blocking I/O Operation with Spring WebFlux.

Step 1: Create the Spring project

We will create the Spring project using Spring Initializr and on creating the project add the below dependencies into the project.

Dependencies:

• Spring Reactive Web
• Spring reactive data for mongodb
• Lombok
• Spring DevTools

Once create the project then the file structure will look like the below image.

Step 2: Configure the Application properties

Open the application.properties fill and add the configuration of the application name and mongodb database of the spring application.

spring.application.name=spring-webflux-IO-Demo
spring.data.mongodb.uri=mongodb://localhost:27017/demo

Step 3: Create the Person class

Go to src > main > java > org.example.springwebfluxiodemo > model > Person and put the below code.

Step 4: Create the PersonRepository class

Go to src > main > java > org.example.springwebfluxiodemo > repository > PersonRepository and put the below code.

Step 5: Create the PersonService class

Go to src > main > java > org.example.springwebfluxiodemo > service > PersonService and put the below code.

Step 6: Create the PersonController class

Go to src > main > java > org.example.springwebfluxiodemo > controller > PersonController and put the below code.

Step 7: Main Class

No changes are required in the main class of the project.

pom.xml:

Step 8: Run the application

Once complete the application then run the application, it will start at port 8080.

Step 9: Testing the Endpoints

Create the Person Endpoint:

POST http://localhost:8080/person

Output:

Get the Persons:

GET http://localhost:8080/persons

Output:

Get the Person by Id:

http://localhost:8080/person/{id}

Output: