Inject middleware in Spring Webflux

Question

I am trying to handle all cross cutting concerns e.g exception, authorization etc. in a project/repo and inject in more than one separate and independent spring-webflux project i.e handling cross-cutting concerns by building a reusable microservice platform.

Can anyone suggest how to accomplish this?

For example:- light4j handle all cross cutting concerns as middleware just need to add as plugin. But it's not compatible with SpringWebflux. Even using AspectJ we can't use same handlers for different projects until or unless they are under same parent project.

I tried to use load-time weaving feature of AspectJ. I defined aspects in different project and add a plugin of that in current project (in which I want to use) but when exception occurred aspectJ part isn't invoked

Below is my pom.xml for current project

<?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>2.5.1</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.dummy</groupId>
    <artifactId>dummydmanagement</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>DummyManagement</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-webflux</artifactId>
        </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>javax.persistence</groupId>
            <artifactId>javax.persistence-api</artifactId>
            <version>2.2</version>
        </dependency>
        <dependency>
            <groupId>io.projectreactor</groupId>
            <artifactId>reactor-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-validator</artifactId>
            <version>5.2.4.Final</version>
        </dependency>
        <dependency>
            <groupId>com.jaway.blog.aspectj</groupId>
            <artifactId>annotations-element-value-pair-without-main-class</artifactId>
            <version>1.0-SNAPSHOT</version>
            <scope>system</scope>
            <systemPath>/home/mmt8281/codebase/annotations-element-value-pair-without-main-class/target/annotations-element-value-pair-without-main-class-1.0-SNAPSHOT.jar</systemPath>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

  

Below is pom.xml of aspect project

<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/maven-v4_0_0.xsd">

    <modelVersion>4.0.0</modelVersion>
    <groupId>com.jaway.blog.aspectj</groupId>
    <version>1.0-SNAPSHOT</version>
    <artifactId>annotations-element-value-pair-without-main-class</artifactId>
    <packaging>jar</packaging>

    <dependencies>
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjrt</artifactId>
            <version>1.8.2</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.3</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                    <encoding>UTF-8</encoding>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>aspectj-maven-plugin</artifactId>
                <version>1.7</version>
                <configuration>
                    <complianceLevel>1.8</complianceLevel>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
                <executions>
                    <execution>
                        <goals>
                            <goal>compile</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>

Attaching gitHub links:-

AspectJ Code
DummyMgmt Code

Answer 1

The problem with "copy & paste programming" is that you use something you do not understand. Maybe it would be better to learn the basics first.

Having said that, there are two ways to solve your problem, given the fact that the aspect module you copied from the blog post is native AspectJ:

1. Configure all applications which want to use the aspect to also use native AspectJ, either by post-compile binary weaving or by load-time weaving. The Spring manual describes how to use LTW.

2. Trivially convert the aspect module to a Spring component and make all client projects use Spring AOP.

The latter is what I did, because I suppose that you only want to use the aspect in Spring projects and that you only annotate public methods in Spring components.

The native AspectJ solution would be more powerful, because it would also work with static and protected/private methods, even for non-Spring code and even outside of Spring completely. But why use a cannon if a pistol is sufficient?

I sent you two pull requests:

• https://github.com/shas2hwat/AspectjMgmt/pull/1
• https://github.com/shas2hwat/DummyManagement/pull/1

What you need to change in the aspect module, is basically this:

• Remove AspectJ Maven plugin
• Add org.springframework:spring-context in order to be able to add @Component to the aspect class.
• I also optimised a few more things, such as update the AspectJ version.

Then, in the application module you need to:

• Add org.aspectj:aspectjweaver
• Add the aspect module's base package name to the component scan
• I also removed the ugly system dependency with the fixed path to the aspect module. If you simply run mvn clean install on the aspect module before you build the application, the library will be found in the local Maven repository. (I think, you need to urgently learn some Maven basics.)

Now when running this application

@SpringBootApplication
@ComponentScan(basePackages = {"com.dummy.dummydmanagement", "com.jayway.blog"})
public class DummyManagementApplication {
    public static void main(String[] args) throws Exception {
        ConfigurableApplicationContext context = SpringApplication.run(DummyManagementApplication.class, args);
        context.getBean(ItemService.class).getAllItemsService();
    }
    // (...)
}

the console log will be:

YourAspect's aroundAdvice's body is now executed Before yourMethodAround is called.

Exception occured
YourAspect's aroundAdvice's body is now executed After yourMethodAround is called.

Of course, annotating the static main method does not work with Spring AOP, which is why I removed the annotation. That would only work with native AspectJ. Please let me know if you need that, but I think you should keep it simple, because you clearly do not understand the tools you are using.

---

Update: Because for whatever reason the OP is angry with me now, because I told him to stop texting me directly on Telegram, he also deleted his own repositories. For anyone interested, here are my clones, containing both the original code and my modifications fixing the problem, as described above:

• https://github.com/kriegaex/AspectjMgmt, relevant commit here
• https://github.com/kriegaex/DummyManagement, relevant commit here