Type mismatch: cannot convert from String to ListenableFuture<String> - spring

Question

I'm trying to implementing non-blocking call. in spring 4, But unfortunately it's throwing the below error.
Type mismatch: cannot convert from String to ListenableFuture
and also same error can not able convert from Map to ListenableFuture>.
My Method call stack is as below.
ListenableFuture<Map<String,String>> unusedQuota = doLogin(userIdentity,request,"0");
doLogin login simply return Map
is there any converter required?
what changes would be required ?
Thanks.
public class MyController {
final DeferredResult<Map<String,String>> deferredResult = new DeferredResult<Map<String,String>>(5000l);
private final Logger log = LoggerFactory.getLogger(MyController.class);
#Inject
RestTemplate restTemplate;
#RequestMapping(value = "/loginservice", method = RequestMethod.GET)
#Timed
public DeferredResult<Map<String,String>> loginRequestService(#RequestParam String userIdentity,HttpServletRequest request) throws Exception {
deferredResult.onTimeout(new Runnable() {
#Override
public void run() { // Retry on timeout
deferredResult.setErrorResult(ResponseEntity.status(HttpStatus.REQUEST_TIMEOUT).body("Request timeout occurred."));
}
});
#SuppressWarnings("unchecked")
ListenableFuture<Map<String,String>> unusedQuota = doLogin(userIdentity,request);
unusedQuota.addCallback(new ListenableFutureCallback<Map<String,String>>() {
#SuppressWarnings("unchecked")
#Override
public void onSuccess(Map<String, String> result) {
// TODO Auto-generated method stub
deferredResult.setResult((Map<String, String>) ResponseEntity.ok(result));
}
#Override
public void onFailure(Throwable t) {
// TODO Auto-generated method stub
deferredResult.setErrorResult(ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body(t));
}
});
return deferredResult;
}
private Map<String,String> doLogin(String userIdentity,HttpServletRequest request) throws Exception{
Map<String,String> unusedQuota=new HashMap<String,String>();
unusedQuota.put("quota", "100");
return unusedQuota;
}
}
}

Answer 1

You are NOT passing the Map object when there is an exception which is causing the issue, so your controller method needs to be changed as shown below, also move deferredResult object inside the Controller method as you should share the same instance of deferredResult for different user request.
public class MyController {
#Autowired
private TaskExecutor asyncTaskExecutor;
#RequestMapping(value = "/loginservice", method = RequestMethod.GET)
#Timed
public DeferredResult<Map<String,String>> loginRequestService(#RequestParam String userIdentity,HttpServletRequest request) throws Exception {
final DeferredResult<Map<String,String>> deferredResult = new DeferredResult<Map<String,String>>(5000l);
deferredResult.onTimeout(new Runnable() {
#Override
public void run() { // Retry on timeout
Map<String, String> map = new HashMap<>();
//Populate map object with error details with Request timeout occurred.
deferredResult.setErrorResult(new ResponseEntity
<Map<String, String>>(map, null,
HttpStatus.REQUEST_TIMEOUT));
}
});
ListenableFuture<String> task = asyncTaskExecutor.submitListenable(new Callable<String>(){
#Override
public Map<String,String> call() throws Exception {
return doLogin(userIdentity,request);
}
});
unusedQuota.addCallback(new ListenableFutureCallback<Map<String,String>>() {
#SuppressWarnings("unchecked")
#Override
public void onSuccess(Map<String, String> result) {
// TODO Auto-generated method stub
deferredResult.setResult((Map<String, String>) ResponseEntity.ok(result));
}
#Override
public void onFailure(Throwable t) {
Map<String, String> map = new HashMap<>();
//Populate map object with error details
deferredResult.setErrorResult(new ResponseEntity<Map<String, String>>(
map, null, HttpStatus.INTERNAL_SERVER_ERROR));
}
});
return deferredResult;
}
}
Also, you need to ensure that you are configuring the ThreadPoolTaskExecutor as explained in the example here.