Hessian Webservice with REST, Java Spring

Question

Is it possible to have a REST service work hand-in-hand with a Hessian service?

To elaborate I have this interface:

@Controller
public interface PhotoServices {

    @RequestMapping(value = "/{user}/{folder_name}/savephoto/", method = RequestMethod.POST)
    public @ResponseBody Object savePhoto(HttpServletRequest request, @PathVariable("user")String user, @PathVariable("folder_name")String folder_name, @ModelAttribute("photo") Photo photo, BindingResult result, SessionStatus session);

    @RequestMapping(value = "/user/getuserphotos/", method = RequestMethod.GET)
    public @ResponseBody Object getUserPhotos(HttpServletRequest request);

    @RequestMapping(value = "/{user}/{folder_name}/photo/{filename}", method = RequestMethod.GET, produces="image/jpg")
    public @ResponseBody byte[] getPhoto(@PathVariable("user")String user, @PathVariable("folder_name")String folder_name, @PathVariable("filename") String filename);

}

I created this interface with the idea of it being a purely RESTful service but changes in requirements needs me to implement a Hessian Service as well.

Using this interface for Hessian as it is has Spring throwing up an error as follows:

12:24:52,765 ERROR http-bio-8080-exec-1 servlet.DispatcherServlet:457 - Context initialization failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping#0': Initialization of bean failed; nested exception is java.lang.IllegalStateException: Ambiguous mapping found. Cannot map 'photoService' bean method 
public java.lang.Object mppiwebservices.photoservices.impl.photo.PhotoServicesImpl.savePhoto(javax.servlet.http.HttpServletRequest,java.lang.String,java.lang.String,mppiwebservices.photoservices.pojo.Photo,org.springframework.validation.BindingResult,org.springframework.web.bind.support.SessionStatus)
to {[/{user}/{folder_name}/savephoto/],methods=[POST],params=[],headers=[],consumes=[],produces=[],custom=[]}: There is already 'photoServicesImpl' bean method
public java.lang.Object mppiwebservices.photoservices.impl.photo.PhotoServicesImpl.savePhoto(javax.servlet.http.HttpServletRequest,java.lang.String,java.lang.String,mppiwebservices.photoservices.pojo.Photo,org.springframework.validation.BindingResult,org.springframework.web.bind.support.SessionStatus) mapped.
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:527)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:294)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:225)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:291)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:585)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:913)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:464)
    at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:631)
    at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:588)
    at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:645)
    at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:508)
    at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:449)
    at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:133)
    at javax.servlet.GenericServlet.init(GenericServlet.java:160)
    at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1228)
    at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1147)
    at org.apache.catalina.core.StandardWrapper.allocate(StandardWrapper.java:836)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:135)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:169)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:929)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:405)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:964)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:515)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:302)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
    at java.lang.Thread.run(Thread.java:722)

which clearly tells me that either I'm integrating REST and Hessian incorrectly or these two cannot exist in the same service at the same time...

So can't Hessian work with REST or am I missing a little line of configuration to make magic happen?

(Extra snippets will be provided if people ask for it..I'm not really sure what you need and I don't want to make a tl;dr post.)

Answer 1

I would recommend that you put the business logic in the serivce in a class marked with @Service which can then have a front end that a controller for http or some other adapter for hessian or RMI or SOAP or whatever is being thrown at you.

// pure business logic method here no dependency on servlets or any network protocol just pojos in
// pojos out 
@Service
public interface PhotoServices {
   public void doSomething(....)

}

/**
* Restful interface knows about Sevlets request and response http status codes ... etc\
* does web stuff and delegates to the PhotoService
*/
@Controller
public class PhotoWebController {

 @Autowired
 private PhotoService photoSerivce;

  @RequestMapping .... 
  public void doSemething(....)
  {
        this.photoSerivce.doSomething(....)
  }
}




/**
* RPC end point understand how to handle error conditions with Hessian ... etc
* 
*/
 // put whatever annoations you need to put for hessian 
public class PhotoHessianController {

 @Autowired
 private PhotoService photoSerivce;

  // hessian annotations go here
  public void doSemething(....)
  {
        this.photoSerivce.doSomething(....)
  }
}

I have not used Hessian so I can't offer details about how to do things with hessian.