| /* |
| * Copyright 2015, 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 io.grpc; |
| |
| import java.net.URI; |
| import java.util.List; |
| import javax.annotation.Nullable; |
| import javax.annotation.concurrent.ThreadSafe; |
| |
| /** |
| * A pluggable component that resolves a target {@link URI} and return addresses to the caller. |
| * |
| * <p>A {@code NameResolver} uses the URI's scheme to determine whether it can resolve it, and uses |
| * the components after the scheme for actual resolution. |
| * |
| * <p>The addresses and attributes of a target may be changed over time, thus the caller registers a |
| * {@link Listener} to receive continuous updates. |
| */ |
| @ExperimentalApi("https://github.com/grpc/grpc-java/issues/1770") |
| @ThreadSafe |
| public abstract class NameResolver { |
| /** |
| * Returns the authority, which is also the name of the service. |
| * |
| * <p>An implementation must generate it locally and <string>must</strong> keep it |
| * unchanged. {@code NameResolver}s created from the same factory with the same argument must |
| * return the same authority. |
| */ |
| public abstract String getServiceAuthority(); |
| |
| /** |
| * Starts the resolution. |
| * |
| * @param listener used to receive updates on the target |
| */ |
| public abstract void start(Listener listener); |
| |
| /** |
| * Stops the resolution. Updates to the Listener will stop. |
| */ |
| public abstract void shutdown(); |
| |
| /** |
| * Re-resolve the name. |
| * |
| * <p>Can only be called after {@link #start} has been called. |
| * |
| * <p>This is only a hint. Implementation takes it as a signal but may not start resolution |
| * immediately. It should never throw. |
| * |
| * <p>The default implementation is no-op. |
| */ |
| public void refresh() {} |
| |
| public abstract static class Factory { |
| /** |
| * The port number used in case the target or the underlying naming system doesn't provide a |
| * port number. |
| */ |
| public static final Attributes.Key<Integer> PARAMS_DEFAULT_PORT = |
| Attributes.Key.of("params-default-port"); |
| |
| /** |
| * Creates a {@link NameResolver} for the given target URI, or {@code null} if the given URI |
| * cannot be resolved by this factory. The decision should be solely based on the scheme of the |
| * URI. |
| * |
| * @param targetUri the target URI to be resolved, whose scheme must not be {@code null} |
| * @param params optional parameters. Canonical keys are defined as {@code PARAMS_*} fields in |
| * {@link Factory}. |
| */ |
| @Nullable |
| public abstract NameResolver newNameResolver(URI targetUri, Attributes params); |
| |
| /** |
| * Returns the default scheme, which will be used to construct a URI when {@link |
| * ManagedChannelBuilder#forTarget(String)} is given an authority string instead of a compliant |
| * URI. |
| */ |
| public abstract String getDefaultScheme(); |
| } |
| |
| /** |
| * Receives address updates. |
| * |
| * <p>All methods are expected to return quickly. |
| */ |
| @ThreadSafe |
| public interface Listener { |
| /** |
| * Handles updates on resolved addresses and attributes. |
| * |
| * <p>Implementations will not modify the given {@code servers}. |
| * |
| * @param servers the resolved server groups, containing {@link ResolvedServerInfo} objects. An |
| * empty list will trigger {@link #onError} |
| * @param attributes extra metadata from naming system |
| */ |
| void onUpdate(List<ResolvedServerInfoGroup> servers, Attributes attributes); |
| |
| /** |
| * Handles an error from the resolver. |
| * |
| * @param error a non-OK status |
| */ |
| void onError(Status error); |
| } |
| } |