CODEWITHSUNDEEP
javaweb-servicesmodel-view-controllerspring-mvc
Juan Antonio Gomez Moriano
Juan Antonio Gomez Moriano

Reputation: 13813

Ensure that web service handles exceptions and always returns a valid response

I am developing a web service, no matter what, the response should always be valid, and I mean valid as in a valid format.

That means that if the web service is expected to return an XML matching a particular XSD schema, it should ALWAYS return a valid XML document, no matter what.

The only approach that I have so far is to do something like this (at controller level)

String xmlResponse = this.loadDefaultXML();
try {
     xmlResponse = this.myCoolService.myCoolMethod();
} catch (Throwable t) {
     xmlResponse = this.loadDefaultXML(String errorMessage)
} finally {
     return xmlResponse
}

Where of course lpoadDefaultXML() will load an xml document like:

<?xml>
<result>Ouch, there was a problem</result>

And loadDefaultXML(String errorMessage) will do

<?xml>
<result>WHATEVER errorMessage contains</result>

Of course the service level takes cares of the normal exceptions, still, I feel that catching Throwable and using the try-catch-finally is the only way to ensure that no matter what, I will be in control so I can return always an XML.

Any better ideas or suggestions?

UPDATE:

I am using Spring MVC 3.2 and JAXB for the marshalling/unmarshalling of xml. This does use SOAP, also I am not using wsdl for this.

Upvotes: 1

Views: 420

Answers (1)

acdcjunior
acdcjunior

Reputation: 135762

In Spring MVC, when an exception is thrown during the handling of the request, the DispatcherServlet will consult the configured org.springframework.web.servlet.HandlerExceptionResolvers to handle the thrown exception. The resolver can then translate the exception to a view to show the user.

To use it, in short, you can either:

  • Implement the HandlerExceptionResolver interface, which is only a matter of implementing the resolveException(Exception, Handler) method and returning a ModelAndView.

Or, what I prefer:

  • You use the @ExceptionHandler method annotation within a controller to specify which method is invoked when an exception of a specific type is thrown during the execution of controller methods. For example:

    @Controller
public class PersonController {

    @RequestMapping("person/{id}")
    @ResponseBody
    public Person getById(@PathVariable String id) {
        if ("007".equals(id)) {
            throw new RuntimeException("007 is a secret agent.");
        }
        return personService.getById(id);
    }

    @ExceptionHandler(RuntimeException.class) // this can be an array
    @ResponseBody
    public String handleRuntimeException(RuntimeException ex,
                                         HttpServletRequest request) {
        return "Oops! Something bad happened: "+ex.getMessage();
    }
}

Find more info at Web MVC framework - Handling Exceptions.

Upvotes: 2

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