code: /*
   * Copyright (c) 2019 the Eclipse Milo Authors
   *
   * This program and the accompanying materials are made
   * available under the terms of the Eclipse Public License 2.0
   * which is available at https://www.eclipse.org/legal/epl-2.0/
   *
   * SPDX-License-Identifier: EPL-2.0
   */
  
  package org.eclipse.milo.opcua.stack.client.transport;
  
  import java.util.concurrent.CompletableFuture;
  
  import org.eclipse.milo.opcua.stack.core.serialization.UaRequestMessage;
  import org.eclipse.milo.opcua.stack.core.serialization.UaResponseMessage;
  
  public interface UaTransport {
  
      /**
       * Connect this transport.
       * <p>
       * Some transports may actually be connection-less (e.g. HTTP), making this method a misnomer, but it should be
       * called to initialize the transport regardless.
       *
       * @return the connected {@link UaTransport} instance.
       */
      CompletableFuture<UaTransport> connect();
  
      /**
       * Disconnect this transport.
       * <p>
       * Some transports may actually be connection-less (e.g. HTTP), making this method a misnomer, but it should be
       * called to un-initialize the transport regardless.
       *
       * @return the disconnected {@link UaTransport} instance.
       */
      CompletableFuture<UaTransport> disconnect();
  
      /**
       * Send a {@link UaRequestMessage}, returning a {@link CompletableFuture} representing the result of the operation.
       *
       * @param request the {@link UaRequestMessage} to send.
       * @return a {@link CompletableFuture} representing the result of the operation.
       */
      CompletableFuture<UaResponseMessage> sendRequest(UaRequestMessage request);
  
  }
  