/*
 * Copyright 2008-present MongoDB, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.mongodb.async.client;

Provides a mechanism for receiving push-based notifications.
 Will receive a call to onSubscribe(Subscription) on subscription to the Observable. No further notifications will be received until Subscription.request(long) is called. 

After signaling demand:

  
One or more invocations of onNext(Object) up to the maximum number defined by Subscription.request(long)
  
Single invocation of onError(Throwable) or onComplete() which signals a terminal state after which no further events will be sent.

 Demand can be signaled via Subscription.request(long) whenever the Observer instance is capable of handling more. 
Type parameters:
<TResult> – The type of element signaled.
Since:
3.1
Deprecated:
Prefer the Reactive Streams-based asynchronous driver (mongodb-driver-reactivestreams artifactId)/**
 * Provides a mechanism for receiving push-based notifications.
 *
 * <p>
 * Will receive a call to {@link #onSubscribe(Subscription)} on subscription to the {@link Observable}.
 * No further notifications will be received until {@link Subscription#request(long)} is called.
 * </p>
 * <p>
 * After signaling demand:
 * <ul>
 *   <li>One or more invocations of {@link #onNext(Object)} up to the maximum number defined by {@link Subscription#request(long)}</li>
 *   <li>Single invocation of {@link #onError(Throwable)} or {@link Observer#onComplete()} which signals a terminal state after which no
 * further events will be sent.</li>
 * </ul>
 * <p>
 * Demand can be signaled via {@link Subscription#request(long)} whenever the {@link Observer} instance is capable of handling more.
 *</p>
 *
 * @param <TResult> The type of element signaled.
 * @since 3.1
 * @deprecated Prefer the Reactive Streams-based asynchronous driver (mongodb-driver-reactivestreams artifactId)
 */
@Deprecated
public interface Observer<TResult> {

    
Invoked on subscription to an Observable. 
 No operation will happen until Subscription.request(long) is invoked. 
 It is the responsibility of this Subscriber instance to call Subscription.request(long) whenever more data is wanted. 
 The MongoIterable will send notifications only in response to Subscription.request(long). 
Params:
subscription – Subscription that allows requesting data via Subscription.request(long)/**
     * Invoked on subscription to an {@link Observable}.
     * <p>
     * No operation will happen until {@link Subscription#request(long)} is invoked.
     * </p>
     * <p>
     * It is the responsibility of this Subscriber instance to call {@link Subscription#request(long)} whenever more data is wanted.
     * </p>
     * <p>
     * The {@link MongoIterable} will send notifications only in response to {@link Subscription#request(long)}.
     * </p>
     *
     * @param subscription {@link Subscription} that allows requesting data via {@link Subscription#request(long)}
     */
    void onSubscribe(Subscription subscription);

    
Provides the Observer with a new item to observe.

The Observer may call this method 0 or more times.

 The Observable will not call this method again after it calls either onComplete or onError. 
Params:
result – the item emitted by the Observable/**
     * Provides the Observer with a new item to observe.
     * <p>
     * The Observer may call this method 0 or more times.
     * </p>
     * <p>
     * The {@link Observable} will not call this method again after it calls either {@link #onComplete} or
     * {@link #onError}.
     *</p>
     *
     * @param result the item emitted by the {@link Observable}
     */
    void onNext(TResult result);

    
Notifies the Observer that the Observable has experienced an error condition. 
 If the Observable calls this method, it will not thereafter call onNext or onComplete.
Params:
e – the exception encountered by the Observable/**
     * Notifies the Observer that the {@link Observable} has experienced an error condition.
     *
     * <p> If the {@link Observable} calls this method, it will not thereafter call {@link #onNext} or {@link #onComplete}.</p>
     *
     * @param e the exception encountered by the {@link Observable}
     */
    void onError(Throwable e);

    
Notifies the Subscriber that the Observable has finished sending push-based notifications. 
 The Observable will not call this method if it calls onError. 
/**
     * Notifies the Subscriber that the {@link Observable} has finished sending push-based notifications.
     * <p>
     * The {@link Observable} will not call this method if it calls {@link #onError}.
     * </p>
     */
    void onComplete();
}