Spring Boot GraphQL Subscription Operation

Spring Boot GraphQL Subscription Operation provides a bi-directional communication over Transmission Control Protocal or TCP socket. The Subscription Operation connects the client to Server via HTTP WebSocket and keeps on pushing data on time interval whereas a Spring Boot GraphQL Query Operation is a one-time pull.

Learn more about Spring Boot GraphQL Query Operation.

Facebook builds GraphQL Subscription Operation to provide real-time “Likes” to users without refreshing the page.

package org.wesome.graphql.controllers;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.graphql.data.method.annotation.SubscriptionMapping;
import org.springframework.stereotype.Controller;
import org.wesome.graphql.entity.Apple;
import org.wesome.graphql.service.AppleService;
import reactor.core.publisher.Flux;

@Controller
public class AppleGraphQLController {
    @Autowired
    private AppleService appleService;

    @SubscriptionMapping("appleSubscribe")
    public Flux<Apple> appleSubscribe() {
        return appleService.findLatest();
    }
}

package org.wesome.graphql.entity;

public record Apple(int appleId, String appleName, String taste, String now) {
}

package org.wesome.graphql.service;

import org.wesome.graphql.entity.Apple;
import reactor.core.publisher.Flux;

public interface AppleService {

    Flux<Apple> findLatest();
}

package org.wesome.graphql.service;


import org.springframework.stereotype.Service;
import org.wesome.graphql.entity.Apple;
import reactor.core.publisher.Flux;

import java.time.Duration;
import java.time.LocalTime;
import java.util.stream.Stream;

@Service
public class AppleServiceImpl implements AppleService {
    @Override
    public Flux<Apple> findLatest() {
        return Flux.fromStream(Stream.generate(() -> new Apple(1, "Fuji", "sweet", LocalTime.now().toString()))).delayElements(Duration.ofSeconds(2));
    }
}

package org.wesome.graphql;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class GraphqlProjectApplication {
    public static void main(String[] args) {
        SpringApplication.run(GraphqlProjectApplication.class, args);
    }
}

\src\main\resources\graphql\schema.graphqls

# Apple Object
type Apple{
    # primary key of apple
    appleId:ID!
    # apple Name
    appleName:String
    # apple Taste
    taste:String
    # current time
    now : String
}
# Apple Subscription 
type Subscription {
    appleSubscribe:Apple
}

\src\main\resources\application.properties

spring.graphql.graphiql.enabled=true
spring.graphql.websocket.path=/graphiql

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://maven.apache.org/POM/4.0.0"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>3.1.5</version>
        <relativePath/>
    </parent>
    <groupId>org.wesome</groupId>
    <artifactId>spring-boot-graphql</artifactId>
    <version>0.0.1-snapshot</version>
    <name>spring boot graphql</name>
    <description>implementing graphql in spring boot</description>
    <properties>
        <java.version>17</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-graphql</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-websocket</artifactId>
        </dependency>
        <dependency>
            <groupId>com.graphql-java-kickstart</groupId>
            <artifactId>graphql-java-tools</artifactId>
            <version>6.0.2</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webflux</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.graphql</groupId>
            <artifactId>spring-graphql-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

GraphiQL

GraphQL provides an inbuild UserInterface GraphiQL, which can be accessed via http://localhost:8080/graphiql or access GraphQL via Postman, in the query section add the below query

subscription appleSubscribe {
    appleSubscribe {
        appleId
        appleName
        taste
        now
    }
}