| /* |
| * Copyright 2014, Google Inc. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions are |
| * met: |
| * |
| * * Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * * Redistributions in binary form must reproduce the above |
| * copyright notice, this list of conditions and the following disclaimer |
| * in the documentation and/or other materials provided with the |
| * distribution. |
| * |
| * * Neither the name of Google Inc. nor the names of its |
| * contributors may be used to endorse or promote products derived from |
| * this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| package com.google.net.stubby; |
| |
| import com.google.common.util.concurrent.ListenableFuture; |
| |
| import javax.annotation.Nullable; |
| |
| /** |
| * Low-level methods for communicating with a remote server during a single RPC. Unlike normal RPCs, |
| * calls may stream any number of requests and responses, although a single request and single |
| * response is most common. This API is generally intended for use by stubs, but advanced |
| * applications may have need for it. |
| * |
| * <p>{@link #start} is required to be the first of any methods called. |
| * |
| * <p>Any headers must be sent before any payloads, which must be sent before half closing. |
| * |
| * <p>No generic method for determining message receipt or providing acknowledgement is provided. |
| * Applications are expected to utilize normal payload messages for such signals, as a response |
| * natually acknowledges its request. |
| * |
| * <p>Methods are guaranteed to be non-blocking. Implementations are not required to be thread-safe. |
| */ |
| public abstract class Call<RequestT, ResponseT> { |
| /** |
| * Callbacks for consuming incoming RPC messages. |
| * |
| * <p>Response headers are guaranteed to arrive before any payloads, which are guaranteed |
| * to arrive before close. An additional block of headers called 'trailers' can be delivered with |
| * close. |
| * |
| * <p>Implementations are free to block for extended periods of time. Implementations are not |
| * required to be thread-safe. |
| */ |
| public abstract static class Listener<T> { |
| |
| /** |
| * The response headers have been received. Headers always precede payloads. |
| * This method is always called, if no headers were received then an empty {@link Metadata} |
| * is passed. |
| */ |
| public abstract ListenableFuture<Void> onHeaders(Metadata.Headers headers); |
| |
| /** |
| * A response payload has been received. For streaming calls, there may be zero payload |
| * messages. |
| */ |
| @Nullable |
| public abstract ListenableFuture<Void> onPayload(T payload); |
| |
| /** |
| * The Call has been closed. No further sending or receiving can occur. If {@code status} is |
| * not equal to {@link Status#OK}, then the call failed. An additional block of headers may be |
| * received at the end of the call from the server. An empty {@link Metadata} object is passed |
| * if no trailers are received. |
| */ |
| public abstract void onClose(Status status, Metadata.Trailers trailers); |
| } |
| |
| /** |
| * Start a call, using {@code responseListener} for processing response messages. |
| * |
| * @param responseListener receives response messages |
| * @param headers which can contain extra information like authentication. |
| * @throws IllegalStateException if call is already started |
| */ |
| // TODO(lryan): Might be better to put into Channel#newCall, might reduce decoration burden |
| public abstract void start(Listener<ResponseT> responseListener, Metadata.Headers headers); |
| |
| /** |
| * Prevent any further processing for this Call. No further messages may be sent or will be |
| * received. The server is informed of cancellations, but may not stop processing the call. |
| * Cancellation is permitted even if previously {@code cancel()}ed or {@link #halfClose}d. |
| */ |
| public abstract void cancel(); |
| |
| /** |
| * Close call for message sending. Incoming messages are unaffected. |
| * |
| * @throws IllegalStateException if call is already {@code halfClose()}d or {@link #cancel}ed |
| */ |
| public abstract void halfClose(); |
| |
| /** |
| * Send a payload message. Payload messages are the primary form of communication associated with |
| * RPCs. Multiple payload messages may exist for streaming calls. |
| * |
| * @param payload message |
| * @throws IllegalStateException if call is {@link #halfClose}d or explicitly {@link #cancel}ed |
| */ |
| public abstract void sendPayload(RequestT payload); |
| } |