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.sdk.client.api.services;
  
  import java.util.List;
  import java.util.concurrent.CompletableFuture;
  
  import org.eclipse.milo.opcua.stack.core.types.structured.CallMethodRequest;
  import org.eclipse.milo.opcua.stack.core.types.structured.CallMethodResult;
  import org.eclipse.milo.opcua.stack.core.types.structured.CallResponse;
  
  import static com.google.common.collect.Lists.newArrayList;
  import static org.eclipse.milo.opcua.stack.core.util.ConversionUtil.l;
  
  public interface MethodServices {
  
      /**
       * This service is used to call (invoke) a list of methods. Each method call is invoked within the context of an
       * existing session. If the session is terminated, the results of the method’s execution cannot be returned to the
       * client and are discarded. This is independent of the task actually performed at the server.
       *
       * @param methodsToCall a list of methods to call.
       * @return a {@link CompletableFuture} containing the {@link CallResponse}.
       */
      CompletableFuture<CallResponse> call(List<CallMethodRequest> methodsToCall);
  
      /**
       * Call (invoke) a method.
       *
       * @param request the {@link CallMethodRequest} describing the method to invoke.
       * @return a {@link CompletableFuture} containing the {@link CallMethodResult}.
       * @see #call(List)
       */
      default CompletableFuture<CallMethodResult> call(CallMethodRequest request) {
          return call(newArrayList(request))
              .thenApply(response -> l(response.getResults()).get(0));
      }
  
  }
  