Spring Webflux change from Netty to Tomcat embedded server-CodePudding

I have changed the pom to switch from Netty to Tomcat as below, but now I get : java.lang.IllegalStateException: No suitable default ClientHttpConnector found, why is that? With Netty before the change was all good.

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     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>2.7.5</version>
    <relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.fer</groupId>
<artifactId>DemoReactive</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>DemoReactive</name>
<description>Demo project for Reactive</description>
<properties>
    <java.version>11</java.version>
</properties>
<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-webflux</artifactId>
        <exclusions>
            <exclusion>
                <artifactId>spring-boot-starter-reactor-netty</artifactId>
                <groupId>org.springframework.boot</groupId>
            </exclusion>
        </exclusions>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-tomcat</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>io.projectreactor</groupId>
        <artifactId>reactor-test</artifactId>
        <scope>test</scope>
    </dependency>
</dependencies>

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

CodePudding user response：

Netty is optimal for Webflux. Don't replace it. The basic principle of operation of the two systems is different. If you want to use Tomcat, use the spring-boot-starter-web dependency, not webflux.

Spring webFlux differrences when Netty vs Tomcat is used under the hood

Spring Web MVC vs Spring WebFlux. Blocking and Non-blocking

Non-blocking programming requires a different approach because you must not block any thread. But you can use a blocker mechanism it just be wrapped.

https://projectreactor.io/docs/core/release/reference/#faq.wrap-blocking

If you want to program like with spring-boot-starter-web pack, not as "stream". I recommend using the Kotlin language with Coroutine, which is two-way compatible with ProjectReactor and Java.

And you can't use thread-based data like Tomcat because more processes can use one thread so there may be thread data that another process can override.

https://projectreactor.io/docs/core/release/reference/#context

CodePudding user response：

I believe this is how you would do something equivalent, note the difference in exclusion:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.example</groupId>
    <artifactId>my-webflux-app</artifactId>
    <version>1.0.0</version>

    <properties>
        <java.version>11</java.version>
        <spring-boot.version>2.3.3.RELEASE</spring-boot.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-webflux</artifactId>
            <exclusions>
                <exclusion>
                    <groupId>io.netty</groupId>
                    <artifactId>netty-all</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>