Run a web application on CRaC
If you are looking to get CRaC-ing with Piranha Servlet you can follow along!
Make sure you are using a CRaC enabled JDK available from https://github.com/CRaC/openjdk-builds/releases
In 10 steps you will learn how to deploy CRaC with Piranha Servlet. They are:
- Create the Maven POM file
- Add the hello.xhtml page
- Add the HelloBean.java file
- Add the web.xml file
- Add the beans.xml file
- Add an integration test
- Test the application
- Start the application
- Create the checkpoint
- Restart the application
Create the Maven POM file
Create an empty directory to store your Maven project. Inside of that directory
create the pom.xml file with the content as below.
<?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>cloud.piranha.guides.servlet</groupId>
<artifactId>crac</artifactId>
<version>24.10.0-SNAPSHOT</version>
<packaging>war</packaging>
<name>Run a web application on Piranha Servlet with CRaC</name>
<properties>
<!-- dependencies -->
<junit.version>5.11.0-M1</junit.version>
<mojarra.version>4.0.6</mojarra.version>
<piranha.version>24.4.0</piranha.version>
<weld.version>5.1.2.Final</weld.version>
<!-- other -->
<java.version>21</java.version>
<piranha.distribution>servlet</piranha.distribution>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<!-- plugins -->
<maven-compiler-plugin.version>3.13.0</maven-compiler-plugin.version>
<maven-failsafe-plugin.version>3.2.5</maven-failsafe-plugin.version>
<maven-war-plugin.version>3.4.0</maven-war-plugin.version>
</properties>
<dependencies>
<!-- compile -->
<dependency>
<groupId>org.glassfish</groupId>
<artifactId>jakarta.faces</artifactId>
<version>${mojarra.version}</version>
<scope>compile</scope>
</dependency>
<dependency>
<groupId>org.jboss.weld.servlet</groupId>
<artifactId>weld-servlet-shaded</artifactId>
<version>${weld.version}</version>
<scope>compile</scope>
</dependency>
<!-- runtime -->
<dependency>
<groupId>cloud.piranha.extension</groupId>
<artifactId>piranha-extension-redhat-weld</artifactId>
<version>${piranha.version}</version>
<scope>runtime</scope>
</dependency>
<!-- test -->
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-api</artifactId>
<version>${junit.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<version>${junit.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-params</artifactId>
<version>${junit.version}</version>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<finalName>crac</finalName>
<plugins>
<plugin>
<groupId>cloud.piranha.maven.plugins</groupId>
<artifactId>piranha-maven-plugin</artifactId>
<version>${piranha.version}</version>
<executions>
<execution>
<id>pre-integration-test</id>
<phase>pre-integration-test</phase>
<goals>
<goal>start</goal>
</goals>
</execution>
<execution>
<id>post-integration-test</id>
<phase>post-integration-test</phase>
<goals>
<goal>stop</goal>
</goals>
</execution>
</executions>
<configuration>
<distribution>servlet</distribution>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>${maven-compiler-plugin.version}</version>
<configuration>
<release>${java.version}</release>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-failsafe-plugin</artifactId>
<version>${maven-failsafe-plugin.version}</version>
<executions>
<execution>
<goals>
<goal>integration-test</goal>
<goal>verify</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-war-plugin</artifactId>
<version>${maven-war-plugin.version}</version>
<configuration>
<failOnMissingWebXml>false</failOnMissingWebXml>
</configuration>
</plugin>
</plugins>
</build>
</project>
Add the Hello XHTML file
Add the helloworld.xhtml file in the src/main/webapp directory.
<?xml version='1.0' encoding='UTF-8' ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html lang="en"
xmlns="http://www.w3.org/1999/xhtml"
xmlns:f="jakarta.faces.core"
xmlns:h="jakarta.faces.html"
xmlns:pt="jakarta.faces.passthrough">
<h:head>
<title>Jakarta Faces application</title>
<meta name="viewport" content="width=device-width, initial-scale=1.0"/>
</h:head>
<h:body>
<div>Jakarta Faces application</div>
<h:form>
<h:outputText value="#{helloBean.hello}"/>
<br/>
</h:form>
</h:body>
</html>
Add the HelloBean.java file
Add the HelloBean.java file in the src/main/java/hello directory.
package hello;
import jakarta.enterprise.context.RequestScoped;
import jakarta.inject.Named;
@Named(value = "helloBean")
@RequestScoped
public class HelloBean {
private String hello = "Hello from CRaC!";
public String getHello() {
return hello;
}
public void setHello(String hello) {
this.hello = hello;
}
}
Add the web.xml file
Add the web.xml file in the src/main/webapp/WEB-INF directory.
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
<servlet>
<servlet-name>Faces Servlet</servlet-name>
<servlet-class>jakarta.faces.webapp.FacesServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>Faces Servlet</servlet-name>
<url-pattern>*.xhtml</url-pattern>
</servlet-mapping>
</web-app>
Add the beans.xml file
Add the beans.xml file in the src/main/webapp/WEB-INF directory.
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/beans_2_0.xsd"
bean-discovery-mode="all">
</beans>
Add an integration test
As we want to make sure the application gets tested before we release an integration test is added which will be executed as part of the build.
We'll add the integration test to the src/test/java directory.
package hello;
import java.net.URI;
import java.net.http.HttpClient;
import static java.net.http.HttpClient.Redirect.ALWAYS;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.net.http.HttpResponse.BodyHandlers;
import java.time.Duration;
import static org.junit.jupiter.api.Assertions.assertTrue;
import org.junit.jupiter.api.Test;
public class HelloIT {
@Test
public void testHelloXhtml() throws Exception {
HttpClient client = HttpClient
.newBuilder()
.connectTimeout(Duration.ofSeconds(60))
.followRedirects(ALWAYS)
.build();
HttpRequest request = HttpRequest
.newBuilder(new URI("http://localhost:8080/crac/hello.xhtml"))
.build();
HttpResponse<String> response = client.send(request, BodyHandlers.ofString());
assertTrue(response.body().contains("Hello from CRaC!"));
}
}
Test the application
The application is setup to use JUnit to do integration testing using the Piranha Maven plugin so when you are building the application it will also execute an integration test validating the web application works.
To build and test the application execute the following command:
mvn install
Deploy the application
To deploy your application you will need 2 pieces.
- The Piranha Servlet runtime JAR.
- The WAR file you just produced.
For the WAR file see the target directory. For the Piranha Servlet
distribution go to Maven Central. And then the following command line will
deploy your application:
java -XX:CRaCCheckpointTo=cr -jar piranha-dist-servlet.jar --enable-crac --write-pid --war-file crac.war &
Create the checkpoint
You have your application currently running so now it is time to create a checkpoint.
To ask the JVM to create a checkpoint use the command line below:
jcmd piranha-dist-servlet.jar JDK.checkpoint
The application will exit and the chechkpoint files are in the cr directory.
Restart the application
To restart the application for the checkpoint you can use the following command line:
java -XX:CRaCRestoreFrom=cr
Conclusion
As you can see using CRaC with Piranha Servlet is matter of the right JDK and the right command line switch.