Setting up a Maven Spring Boot Project

CaptainCasa by default uses a separate Tomcat servlet container in which web applications are deployed at development time (reload within toolset) or in production scenarios (.war deployment). Of course any other servlet container (Jetty, JBoss, ...) can be used that supports Servlet API 3.1.

Since Q3/2020 there is a alternative runtime which is Spring Boot. Spring Boot is liked by many developers because it produces self containing result files (.jar or .war) which incorporate the runtime container (Tomcat), so that you do not require an explicit e.g. Tomcat installation to deploy your system to – you can directly run it from the .jar or .war file.

Spring Boot Support

The CaptainCasa Spring Boot integration includes the following functions:

“Normal” creation of .war/.jar packaged Spring Boot result files
Reloading of classes using Spring's live reload functions

Setting up a Spring Boot Project

All you need to do is:

Create a Maven-project – exactly following the description of the previous chapter
But: select as project archetype “eclntwebapparchetype_springboot”:

All other steps are the same (including import into Layout Editor and editing first layout definitions) as with the normal creation of Maven projects.

Some more inner details

Starter class

The project archetype adds some Spring-Starter class into the project:

package springbootstartup;

import java.util.HashSet;

import java.util.Set;

import javax.servlet.ServletContext;

import javax.servlet.ServletException;

import javax.servlet.SessionTrackingMode;

import org.eclnt.jsfserver.managedbean.HotDeployManager;

import org.eclnt.jsfserver.util.CCInitialize;

import org.springframework.boot.SpringApplication;

import org.springframework.boot.autoconfigure.SpringBootApplication;

import org.springframework.boot.web.servlet.ServletContextInitializer;

import org.springframework.context.ApplicationContext;

import org.springframework.context.annotation.Bean;

import org.springframework.web.context.ServletContextAware;

import org.springframework.web.socket.server.standard.ServerEndpointExporter;

@SpringBootApplication

public class SBApplication

{

public static void main(String[] args)

{

SpringApplication.run(SBApplication.class, args);

}

@Bean

public ServletContextAware endpointExporterInitializer(final ApplicationContext applicationContext)

{

return new ServletContextAware()

{

@Override

public void setServletContext(ServletContext servletContext)

{

// code from https://stackoverflow.com/questions/25390100/using-java-api-for-websocket-jsr-356-with-spring-boot

ServerEndpointExporter exporter = new ServerEndpointExporter();

exporter.setApplicationContext(applicationContext);

exporter.afterPropertiesSet();

// initialize web socket management which was left out in "big" intialization

CCInitialize.postInitializeWebSocketPolling(servletContext);

}

};

}

@Bean

public ServletContextInitializer initializer()

{

return new ServletContextInitializer()

{

@Override

public void onStartup(ServletContext servletContext) throws ServletException

{

// set tracking mode

Set<SessionTrackingMode> stms = new HashSet<>();

stms.add(SessionTrackingMode.URL);

servletContext.setSessionTrackingModes(stms);

// initialize

CCInitialize.setInitWebSocketPolling(false); // is initialized in endpointExporterInitializer

CCInitialize.initializeCCEnvironment(servletContext,true); // true => forceReset!

// set classloader in HotDeployManager in order to support live reload

HotDeployManager.setCurrentParentClassLoader(SBApplication.this.getClass().getClassLoader());

HotDeployManager.triggerCreationOfNewInstance();

}

};

}

You can move this class to any package of your choice – all relevant Spring parts are annotated and will be discovered automatically by Spring.

The “SBApplication” class contains the instructions how to start the CaptainCasa runtime within the Spring Boot container. The central method to do so is “CCInitialize.initializeCCEnvironment(...)” - but there are other, special definitions as well:

The session tracking mode (URL or Cookie) needs to be initialized
The initialization of CaptainCasa's web socket management must not be executed as part fo the normal starting process but must be done later in method “endpointExporterInitializer(...)”
The CaptainCasa hot deploy management must be notified about the current Spring class loader (which is esp. important when using Spring live reload).

Starting the Spring Boot container

Normal starting

While in the normal Maven project you use “mvn clean install” to build the project, you now use “mvn clean spring-boot:run” to build and start your project.

Because CaptainCasa's layout tools require access to the “.war” image of the project we recommend to combine both and always call:

mvn clean install spring-boot:run

As result both the .war image will be built and the Spring Boot runtime will be started.

Starting in debug mode

There are several ways to start the Spring Boot container in debug mode. One way is to adapt the pom.xml in the following way:

...

<build>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-maven-plugin</artifactId>

-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=50010

</jvmArguments>

</configuration>

</plugin>

</plugins>

</build>

...

Using live-reload

The live reload functions of Spring can be just used in a normal way. This means: you have to add the following to your pom.xml:

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-devtools</artifactId>

</dependency>