Parent POM implementation in Mule

Why parent POM: One reason to use a parent POM is to have a central place to store common dependencies, Properties, configuration, version that can be inherited by child POM, it´s just useful to manage shared resources and have a single point of modification to update your projects.

Example: If you have the DB Connector version specified in a parent pom, then any project depending on that parent pom, can be rebuilt with Maven after changing the parent pom DB connector version, and every project would update their internal DB Connector without actually modifying the API at all.

In current POC, i will use an application’s POM, create a Parent POM to store versions, common properties, dependencies and refer it in application’s POM.

Application’s pom.xml:

<?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>

<groupId>com.mycompany</groupId>
 <artifactId>pombom</artifactId>
 <version>1.0.0-SNAPSHOT</version>
 <packaging>mule-application</packaging>

 <name>pombom</name>

 <properties>
  <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
  <app.runtime>4.5.1</app.runtime>
  <mule.maven.plugin.version>4.0.0</mule.maven.plugin.version>
 </properties>

 <build>
  <plugins>
   <plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-clean-plugin</artifactId>
    <version>3.2.0</version>
   </plugin>
   <plugin>
    <groupId>org.mule.tools.maven</groupId>
    <artifactId>mule-maven-plugin</artifactId>
    <version>${mule.maven.plugin.version}</version>
    <extensions>true</extensions>
    <configuration>
     <sharedLibraries>
      <sharedLibrary>
       <groupId>mysql</groupId>
       <artifactId>mysql-connector-java</artifactId>
      </sharedLibrary>
     </sharedLibraries>
    </configuration>
   </plugin>
  </plugins>
 </build>

 <dependencies>
  <dependency>
   <groupId>org.mule.connectors</groupId>
   <artifactId>mule-http-connector</artifactId>
   <version>1.8.0</version>
   <classifier>mule-plugin</classifier>
  </dependency>
  <dependency>
   <groupId>org.mule.connectors</groupId>
   <artifactId>mule-sockets-connector</artifactId>
   <version>1.2.3</version>
   <classifier>mule-plugin</classifier>
  </dependency>
  <dependency>
   <groupId>org.mule.connectors</groupId>
   <artifactId>mule-db-connector</artifactId>
   <version>1.14.6</version>
   <classifier>mule-plugin</classifier>
  </dependency>
  <dependency>
   <groupId>mysql</groupId>
   <artifactId>mysql-connector-java</artifactId>
   <version>8.0.30</version>
  </dependency>
 </dependencies>
 <repositories>
  <repository>
   <id>anypoint-exchange-v3</id>
   <name>Anypoint Exchange</name>
   <url>https://maven.anypoint.mulesoft.com/api/v3/maven</url>
   <layout>default</layout>
  </repository>
  <repository>
   <id>mulesoft-releases</id>
   <name>MuleSoft Releases Repository</name>
   <url>https://repository.mulesoft.org/releases/</url>
   <layout>default</layout>
  </repository>
 </repositories>
 
<pluginRepositories>
  <pluginRepository>
   <id>mulesoft-releases</id>
   <name>MuleSoft Releases Repository</name>
   <layout>default</layout>
   <url>https://repository.mulesoft.org/releases/</url>
   <snapshots>
    <enabled>false</enabled>
   </snapshots>
  </pluginRepository>
 </pluginRepositories>
</project>

Application’s POM.xml

Steps to be followed to create a parent POM:

1. Go to your workspace and create a folder know as parent-pom and create pom.xml in it.
2. Copy paste content of your application’s pom.xml to parent pom.xml
3. Now pom.xml and parent pom. xml has same content.
4. Coming on to properties in pom.xml , below sourceEncoding, outputEncoding, runtime, maven.plugin.version are not application specific so can be kept in parent pom and removed from application’s pom.xml

  <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
  <app.runtime>4.5.1</app.runtime>
  <mule.maven.plugin.version>4.0.0</mule.maven.plugin.version>

5. For plugins, we would want plugin and configurations to be inherited from parent pom.xml so will wrap plugins in parent pom under <pluginManagement> tag and remove versions from plugin in application’s pom.xml.

Parent POM.xml

6. For dependencies, we will enclose all dependencies under <dependencyManagement> tag in parent pom.xml and will remove dependency versions for all dependencies from application pom.xml as will be inherited from parent pom.xml

Parent pom.xml

7. repositories and pluginRepositories will be referred from parent pom.xml hence can be removed from application’s pom.xml

8. For parent pom, packaging type will be pom

<groupId>2b4250b3-0421-4fa9-8e2a-126b5ef25a5a</groupId>
 <artifactId>parent-pom</artifactId>
 <version>1.0.0</version>
 <packaging>pom</packaging>

For application’s pom.xml , add below to refer parent pom.xml from maven repository:

<parent>
 <groupId>2b4250b3-0421-4fa9-8e2a-126b5ef25a5a</groupId>
 <artifactId>parent-pom</artifactId>
 <version>1.0.0</version>
 <relativePath>../parent-pom/pom.xml</relativePath>
 </parent>

You can get error in application’s pom.xml when its not able to find parent pom.xml , so in that case you have to run mvn clean install for parent pom to be available in local maven repo.

Application’s POM.xml post changes:

<?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>2b4250b3-0421-4fa9-8e2a-126b5ef25a5a</groupId>
 <artifactId>parent-pom</artifactId>
 <version>1.0.0-SNAPSHOT</version>
 <relativePath/>
 </parent>

 <groupId>2b4250b3-0421-4fa9-8e2a-126b5ef25a5a</groupId>
 <artifactId>demo</artifactId>
 <version>1.0.0-SNAPSHOT</version>
 <packaging>mule-application</packaging>

 <name>demo</name>

 <build>
  <plugins>
   <plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-clean-plugin</artifactId>
   </plugin>
   
  </plugins>
 </build>
 <dependencies>
  <dependency>
   <groupId>org.mule.connectors</groupId>
   <artifactId>mule-http-connector</artifactId>
   <classifier>mule-plugin</classifier>
  </dependency>
  <dependency>
   <groupId>org.mule.connectors</groupId>
   <artifactId>mule-sockets-connector</artifactId>
   <classifier>mule-plugin</classifier>
  </dependency>
  <dependency>
   <groupId>org.mule.connectors</groupId>
   <artifactId>mule-db-connector</artifactId>
   <classifier>mule-plugin</classifier>
  </dependency>
  <dependency>
   <groupId>mysql</groupId>
   <artifactId>mysql-connector-java</artifactId>
  </dependency>
 </dependencies>
 
</project>

Parent POM.xml post modification:

<?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>

<groupId>2b4250b3-0421-4fa9-8e2a-126b5ef25a5a</groupId>
 <artifactId>parent-pom</artifactId>
 <version>1.0.0-SNAPSHOT</version>
 <packaging>pom</packaging>

 <name>parent-pom</name>

 <properties>
  <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
  <app.runtime>4.5.1</app.runtime>
  <mule.maven.plugin.version>4.0.0</mule.maven.plugin.version>
 </properties>

 <build>
  <pluginManagement>
  <plugins>
   <plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-clean-plugin</artifactId>
    <version>3.2.0</version>
   </plugin>
   <plugin>
    <groupId>org.mule.tools.maven</groupId>
    <artifactId>mule-maven-plugin</artifactId>
    <version>${mule.maven.plugin.version}</version>
    <extensions>true</extensions>
    <configuration>
     <sharedLibraries>
      <sharedLibrary>
       <groupId>mysql</groupId>
       <artifactId>mysql-connector-java</artifactId>
      </sharedLibrary>
     </sharedLibraries>
    </configuration>
   </plugin>
  </plugins>
  </pluginManagement>
 </build>
        
<dependencyManagement>
 <dependencies>
  <dependency>
   <groupId>org.mule.connectors</groupId>
   <artifactId>mule-http-connector</artifactId>
   <version>1.8.0</version>
   <classifier>mule-plugin</classifier>
  </dependency>
  <dependency>
   <groupId>org.mule.connectors</groupId>
   <artifactId>mule-sockets-connector</artifactId>
   <version>1.2.3</version>
   <classifier>mule-plugin</classifier>
  </dependency>
  <dependency>
   <groupId>org.mule.connectors</groupId>
   <artifactId>mule-db-connector</artifactId>
   <version>1.14.6</version>
   <classifier>mule-plugin</classifier>
  </dependency>
  <dependency>
   <groupId>mysql</groupId>
   <artifactId>mysql-connector-java</artifactId>
   <version>8.0.30</version>
  </dependency>
 </dependencies>
</dependencyManagement>
 <repositories>
  <repository>
   <id>anypoint-exchange-v3</id>
   <name>Anypoint Exchange</name>
   <url>https://maven.anypoint.mulesoft.com/api/v3/maven</url>
   <layout>default</layout>
  </repository>
  <repository>
   <id>mulesoft-releases</id>
   <name>MuleSoft Releases Repository</name>
   <url>https://repository.mulesoft.org/releases/</url>
   <layout>default</layout>
  </repository>
 </repositories>
 <pluginRepositories>
  <pluginRepository>
   <id>mulesoft-releases</id>
   <name>MuleSoft Releases Repository</name>
   <layout>default</layout>
   <url>https://repository.mulesoft.org/releases/</url>
   <snapshots>
    <enabled>false</enabled>
   </snapshots>
  </pluginRepository>
 </pluginRepositories>
</project>