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package javax.ws.rs.container;
import java.util.Collection;
import java.util.Date;
import java.util.Map;
import java.util.concurrent.TimeUnit;
/**
* An injectable JAX-RS asynchronous response that provides means for asynchronous server side
* response processing.
*
* A new instance of {@code AsyncResponse} may be injected into a
* {@link javax.ws.rs.HttpMethod resource or sub-resource method} parameter using
* the {@link Suspended @Suspend} annotation.
*
* Each asynchronous response instance is bound to the running request and can be used to
* asynchronously provide the request processing result or otherwise manipulate the suspended
* client connection. The available operations include:
*
* - updating suspended state data (time-out value, response ...)
* - resuming the suspended request processing
* - canceling the suspended request processing
*
*
*
* Following example demonstrates the use of the {@code AsyncResponse} for asynchronous
* HTTP request processing:
*
*
* @Path("/messages/next")
* public class MessagingResource {
* private static final BlockingQueue<AsyncResponse> suspended =
* new ArrayBlockingQueue<AsyncResponse>(5);
*
* @GET
* public void readMessage(@Suspended AsyncResponse ar) throws InterruptedException {
* suspended.put(ar);
* }
*
* @POST
* public String postMessage(final String message) throws InterruptedException {
* final AsyncResponse ar = suspended.take();
* ar.resume(message); // resumes the processing of one GET request
* return "Message sent";
* }
* }
*
*
* If the asynchronous response was suspended with a positive timeout value, and has
* not been explicitly resumed before the timeout has expired, the processing
* will be resumed once the specified timeout threshold is reached, provided a positive
* timeout value was set on the response.
*
*
* By default a timed-out asynchronous response is resumed with a {@link javax.ws.rs.WebApplicationException}
* that has {@link javax.ws.rs.core.Response.Status#SERVICE_UNAVAILABLE HTTP 503 (Service unavailable)}
* error response status code set. This default behavior may be overridden by
* {@link AsyncResponse#setTimeoutHandler(TimeoutHandler) setting} a custom {@link TimeoutHandler time-out handler}.
*
*
* @author Marek Potociar
* @since 2.0
*/
public interface AsyncResponse {
/**
* Constant specifying no suspend timeout value.
*/
public static final long NO_TIMEOUT = 0;
/**
* Resume the suspended request processing using the provided response data.
*
* The provided response data can be of any Java type that can be
* returned from a {@link javax.ws.rs.HttpMethod JAX-RS resource method}.
*
* The asynchronous response must be still in a {@link #isSuspended() suspended} state
* for this method to succeed.
*
*
* By executing this method, the request is guaranteed to complete either successfully or
* with an error. The data processing by the JAX-RS runtime follows the same path
* as it would for the response data returned synchronously by a JAX-RS resource,
* except that unmapped exceptions are not re-thrown by JAX-RS runtime to be handled by
* a hosting I/O container. Instead, any unmapped exceptions are propagated to the hosting
* I/O container via a container-specific callback mechanism. Depending on the container
* implementation, propagated unmapped exceptions typically result in an error status
* being sent to the client and/or the connection being closed.
*
*
* @param response data to be sent back in response to the suspended request.
* @return {@code true} if the request processing has been resumed, returns {@code false} in case
* the request processing is not {@link #isSuspended() suspended} and could not be resumed.
* @see #resume(Throwable)
*/
public boolean resume(Object response);
/**
* Resume the suspended request processing using the provided throwable.
*
* For the provided throwable same rules apply as for an exception thrown
* by a {@link javax.ws.rs.HttpMethod JAX-RS resource method}.
*
* By executing this method, the request is guaranteed to complete either successfully or
* with an error. The throwable processing by the JAX-RS runtime follows the same path
* as it would for the response data returned synchronously by a JAX-RS resource,
* except that unmapped exceptions are not re-thrown by JAX-RS runtime to be handled by
* a hosting I/O container. Instead, any unmapped exceptions are propagated to the hosting
* I/O container via a container-specific callback mechanism. Depending on the container
* implementation, propagated unmapped exceptions typically result in an error status
* being sent to the client and/or the connection being closed.
*
*
* @param response an exception to be raised in response to the suspended
* request.
* @return {@code true} if the response has been resumed, returns {@code false} in case
* the response is not {@link #isSuspended() suspended} and could not be resumed.
* @see #resume(Object)
*/
public boolean resume(Throwable response);
/**
* Cancel the suspended request processing.
*
* When a request processing is cancelled using this method, the JAX-RS implementation
* MUST indicate to the client that the request processing has been cancelled by sending
* back a {@link javax.ws.rs.core.Response.Status#SERVICE_UNAVAILABLE HTTP 503 (Service unavailable)}
* error response.
*
*
* Invoking a {@code cancel(...)} method multiple times to cancel request processing has the same
* effect as canceling the request processing only once. Invoking a {@code cancel(...)} method on
* an asynchronous response instance that has already been cancelled or resumed has no effect and the
* method call is ignored while returning {@code true}, in case the request has been cancelled previously.
* Otherwise, in case the request has been resumed regularly (using a {@code resume(...) method}) or
* resumed due to a time-out, method returns {@code false}.
*
*
* @return {@code true} if the request processing has been cancelled, returns {@code false} in case
* the request processing is not {@link #isSuspended() suspended} and could not be cancelled
* and is not {@link #isCancelled() cancelled} already.
* @see #cancel(int)
* @see #cancel(java.util.Date)
*/
public boolean cancel();
/**
* Cancel the suspended request processing.
*
* When a request processing is cancelled using this method, the JAX-RS implementation
* MUST indicate to the client that the request processing has been cancelled by sending
* back a {@link javax.ws.rs.core.Response.Status#SERVICE_UNAVAILABLE HTTP 503 (Service unavailable)}
* error response with a {@code Retry-After} header set to the value provided by the method
* parameter.
*
*
* Invoking a {@code cancel(...)} method multiple times to cancel request processing has the same
* effect as canceling the request processing only once. Invoking a {@code cancel(...)} method on
* an asynchronous response instance that has already been cancelled or resumed has no effect and the
* method call is ignored while returning {@code true}, in case the request has been cancelled previously.
* Otherwise, in case the request has been resumed regularly (using a {@code resume(...) method}) or
* resumed due to a time-out, method returns {@code false}.
*
*
* @param retryAfter a decimal integer number of seconds after the response is sent to the client that
* indicates how long the service is expected to be unavailable to the requesting
* client.
* @return {@code true} if the request processing has been cancelled, returns {@code false} in case
* the request processing is not {@link #isSuspended() suspended} and could not be cancelled
* and is not {@link #isCancelled() cancelled} already.
* @see #cancel
* @see #cancel(java.util.Date)
*/
public boolean cancel(int retryAfter);
/**
* Cancel the suspended request processing.
*
* When a request processing is cancelled using this method, the JAX-RS implementation
* MUST indicate to the client that the request processing has been cancelled by sending
* back a {@link javax.ws.rs.core.Response.Status#SERVICE_UNAVAILABLE HTTP 503 (Service unavailable)}
* error response with a {@code Retry-After} header set to the value provided by the method
* parameter.
*
*
* Invoking a {@code cancel(...)} method multiple times to cancel request processing has the same
* effect as canceling the request processing only once. Invoking a {@code cancel(...)} method on
* an asynchronous response instance that has already been cancelled or resumed has no effect and the
* method call is ignored while returning {@code true}, in case the request has been cancelled previously.
* Otherwise, in case the request has been resumed regularly (using a {@code resume(...) method}) or
* resumed due to a time-out, method returns {@code false}.
*
*
* @param retryAfter a date that indicates how long the service is expected to be unavailable to the
* requesting client.
* @return {@code true} if the request processing has been cancelled, returns {@code false} in case
* the request processing is not {@link #isSuspended() suspended} and could not be cancelled
* and is not {@link #isCancelled() cancelled} already.
* @see #cancel
* @see #cancel(int)
*/
public boolean cancel(Date retryAfter);
/**
* Check if the asynchronous response instance is in a suspended state.
*
* Method returns {@code true} if this asynchronous response is still suspended and has
* not finished processing yet (either by resuming or canceling the response).
*
* @return {@code true} if this asynchronous response is in a suspend state, {@code false}
* otherwise.
* @see #isCancelled()
* @see #isDone()
*/
public boolean isSuspended();
/**
* Check if the asynchronous response instance has been cancelled.
*
* Method returns {@code true} if this asynchronous response has been canceled before
* completion.
*
* @return {@code true} if this task was canceled before completion.
* @see #isSuspended()
* @see #isDone()
*/
public boolean isCancelled();
/**
* Check if the processing of a request this asynchronous response instance belongs to
* has finished.
*
* Method returns {@code true} if the processing of a request this asynchronous response
* is bound to is finished.
*
* The request processing may be finished due to a normal termination, a suspend timeout, or
* cancellation -- in all of these cases, this method will return {@code true}.
*
*
* @return {@code true} if this execution context has finished processing.
* @see #isSuspended()
* @see #isCancelled()
*/
public boolean isDone();
/**
* Set/update the suspend timeout.
*
* The new suspend timeout values override any timeout value previously specified.
* The asynchronous response must be still in a {@link #isSuspended() suspended} state
* for this method to succeed.
*
*
* @param time suspend timeout value in the give time {@code unit}. Value lower
* or equal to 0 causes the context to suspend indefinitely.
* @param unit suspend timeout value time unit.
* @return {@code true} if the suspend time out has been set, returns {@code false} in case
* the request processing is not in the {@link #isSuspended() suspended} state.
*/
public boolean setTimeout(long time, TimeUnit unit);
/**
* Set/replace a time-out handler for the suspended asynchronous response.
*
* The time-out handler will be invoked when the suspend period of this
* asynchronous response times out. The job of the time-out handler is to
* resolve the time-out situation by either
*
* - resuming the suspended response
* - cancelling the suspended response
* - extending the suspend period by setting a new suspend time-out
*
*
*
* Note that in case the response is suspended {@link #NO_TIMEOUT indefinitely},
* the time-out handler may never be invoked.
*
*
* @param handler response time-out handler.
*/
public void setTimeoutHandler(TimeoutHandler handler);
/**
* Register an asynchronous processing lifecycle callback class to receive lifecycle
* events for the asynchronous response based on the implemented callback interfaces.
*
* @param callback callback class.
* @return collection of registered callback interfaces. If the callback class does not
* implement any recognized callback interfaces, the returned collection will be
* empty.
* @throws NullPointerException in case the callback class is {@code null}.
*/
public Collection> register(Class callback);
/**
* Register asynchronous processing lifecycle callback classes to receive lifecycle
* events for the asynchronous response based on the implemented callback interfaces.
*
* @param callback callback class.
* @param callbacks additional callback classes.
* @return map of registered classes and the callback interfaces registered for each class.
* If a callback class does not implement any recognized callback interfaces, the
* associated collection of registered interfaces for the class will be empty.
* @throws NullPointerException in case any of the callback classes is {@code null}.
*/
public Map, Collection>> register(Class callback, Class... callbacks);
/**
* Register an asynchronous processing lifecycle callback instance to receive lifecycle
* events for the asynchronous response based on the implemented callback interfaces.
*
* @param callback callback instance implementing one or more of the recognized callback
* interfaces.
* @return collection of registered callback interfaces. If the callback class does not
* implement any recognized callback interfaces, the returned collection will be
* empty.
* @throws NullPointerException in case the callback instance is {@code null}.
*/
public Collection> register(Object callback);
/**
* Register an asynchronous processing lifecycle callback instances to receive lifecycle
* events for the asynchronous response based on the implemented callback interfaces.
*
* @param callback callback instance.
* @param callbacks additional callback instances.
* @return map of registered classes and the callback interfaces registered for each class.
* If a callback class does not implement any recognized callback interfaces, the
* associated collection of registered interfaces for the class will be empty.
* @throws NullPointerException in case any of the callback instances is {@code null}.
*/
public Map, Collection>> register(Object callback, Object... callbacks);
}