Question

I am writing Apache CXF web services and use Spring for loading my beans. My only bean is calling external process (MATLAB) from Java. My beans definition looks as below:

<bean id="matlabEngine" class="org.burch.pca.matlab.MatlabEngine"
    init-method="start" scope="singleton">
    <constructor-arg value="${matlab.engine.path}"></constructor-arg>
</bean>

<bean
    class="org.springframework.web.context.support.ServletContextPropertyPlaceholderConfigurer">
    <property name="systemPropertiesModeName" value="SYSTEM_PROPERTIES_MODE_OVERRIDE" />
    <property name="searchContextAttributes" value="true" />
    <property name="contextOverride" value="true" />
    <property name="ignoreResourceNotFound" value="true" />
    <property name="locations">
        <list>
            <value>classpath:/pca-engine.properties</value>
        </list>
    </property>
</bean>

Piece of my MatlabEngine bean is as below:

/**
 * Path to MATLAB engine.
 */
private String pathToEngine;

public MatlabEngine(String pathToEngine) throws MatlabConnectionException, MatlabInvocationException{
    super();
    setPathToEngine(pathToEngine);
}

/**
 * Starts engine and goes to path defined by argument
 * @param pathToEngine
 * @throws MatlabConnectionException
 * @throws MatlabInvocationException
 */
public void start() throws MatlabConnectionException, MatlabInvocationException{
  //Create a factory
  RemoteMatlabProxyFactory factory = new RemoteMatlabProxyFactory();

  //Get a proxy, launching MATLAB in the process
  proxy = factory.getProxy();

  //Display welcoming messages in MATLAB Command Window
  proxy.eval(MatlabCommandsRegistry.disp(MATLAB_ENGINE_WELCOME_1));
  proxy.eval(MatlabCommandsRegistry.disp(MATLAB_ENGINE_WELCOME_2));

  if(pathToEngine!= null && !"".equals(pathToEngine)){
      logM("Switching to engine directory...");
      String goToEngineRootDir = MatlabCommandsRegistry.cd(pathToEngine);
      proxy.eval(goToEngineRootDir);
      logM("Sucessfully changed engine dir to "+pathToEngine);
  }
}

When I deploy web services in Tomcat, it brings up MATLAB process nicely (bean gets loaded).

However, when I create client request to web service endpoint with this code:

public static void main(String args[]) throws Exception {

    JaxWsProxyFactoryBean factory = new JaxWsProxyFactoryBean();

    factory.getInInterceptors().add(new LoggingInInterceptor());
    factory.getOutInterceptors().add(new LoggingOutInterceptor());
    factory.setServiceClass(UploadService.class);
    factory.setAddress("http://localhost:8080/auth-ws-1.0.0/services/upload");
    UploadService client = (UploadService) factory.create();

    UploadEntity resume=new UploadEntity();
    resume.setFileName("Image490");
    resume.setFileType("jpg");

    //Work arround data handler....
    DataSource source = new FileDataSource(new File("C:\\Users\\Pictures\\thumb.png"));
    DataHandler dataHandle = new DataHandler(source);
    ByteArrayOutputStream stream = new ByteArrayOutputStream();
    dataHandle.writeTo(stream);
    resume.setPayload(stream.toByteArray());
    client.uploadFile(resume);
    System.exit(0);

}

my server brings out new instance of MATLAB process (bean gets loaded again – very heavy and undesirable). What could I do to have only one bean which will be used to serve all processing and all requests? I am new to Spring, and I am thinking that my problem is that I am dealing with multiple contexts here. I want them to share a single instance of a singleton bean but don’t know how to manage this.

Thank you for your time!

Answer 1

You should enable singleton mode for you bean.

Look at this: http://static.springsource.org/spring/docs/1.2.x/reference/beans.html#beans-factory-modes

Bean defenition may looks like this:

<!-- Spring property loading bean -->
<bean
    class="org.springframework.web.context.support.ServletContextPropertyPlaceholderConfigurer" singleton="true">
    <property name="systemPropertiesModeName" value="SYSTEM_PROPERTIES_MODE_OVERRIDE" />
    <property name="searchContextAttributes" value="true" />
    <property name="contextOverride" value="true" />
    <property name="ignoreResourceNotFound" value="true" />
    <property name="locations">
        <list>
            <value>classpath:/pca-engine.properties</value>
        </list>
    </property>
</bean>

I think you should manage MATLAB process lifecircle wisely to decrease resource loading.