/// <summary>
        /// Initiates the asynchronous execution of the DescribeInstances operation.
        /// </summary>
        /// 
        /// <param name="request">Container for the necessary parameters to execute the DescribeInstances operation.</param>
        /// <param name="cancellationToken">
        ///     A cancellation token that can be used by other objects or threads to receive notice of cancellation.
        /// </param>
        /// <returns>The task object representing the asynchronous operation.</returns>
        public Task<DescribeInstancesResponse> DescribeInstancesAsync(DescribeInstancesRequest request, System.Threading.CancellationToken cancellationToken = default(CancellationToken))
        {
            var marshaller = new DescribeInstancesRequestMarshaller();
            var unmarshaller = DescribeInstancesResponseUnmarshaller.Instance;

            return InvokeAsync<DescribeInstancesRequest,DescribeInstancesResponse>(request, marshaller, 
                unmarshaller, cancellationToken);
        }

        public void DescribeInstancesMarshallTest()
        {
            var operation = service_model.FindOperation("DescribeInstances");

            var request = InstantiateClassGenerator.Execute<DescribeInstancesRequest>();
            var marshaller = new DescribeInstancesRequestMarshaller();
            var internalRequest = marshaller.Marshall(request);
            var validator = new AWSQueryValidator(internalRequest.Parameters, request, service_model, operation);
            validator.Validate();


            var payloadResponse = new XmlSampleGenerator(service_model, operation).Execute();
            UnmarshallerContext context = new EC2UnmarshallerContext(Utils.CreateStreamFromString(payloadResponse), false, new WebResponseData());
            var response = DescribeInstancesResponseUnmarshaller.Instance.Unmarshall(context)
                as DescribeInstancesResponse;   
            InstantiateClassGenerator.ValidateObjectFullyInstantiated(response);       
        }

        public void DescribeInstancesMarshallTest()
        {
            var request = InstantiateClassGenerator.Execute<DescribeInstancesRequest>();
            var marshaller = new DescribeInstancesRequestMarshaller();

            var internalRequest = marshaller.Marshall(request);
            var jsonRequest = UTF8Encoding.UTF8.GetString(internalRequest.Content);                        
            Comparer.CompareObjectToJson<DescribeInstancesRequest>(request,jsonRequest);

            var webResponse = new WebResponseData
            {
                Headers = {
                    {"x-amzn-RequestId", Guid.NewGuid().ToString()},
                    {"x-amz-crc32","0"}
                }
            };
            var jsonResponse = new JsonSampleGenerator(service_model, service_model.FindOperation("DescribeInstances").ResponseStructure).Execute();
            webResponse.Headers.Add("Content-Length", UTF8Encoding.UTF8.GetBytes(jsonResponse).Length.ToString());
            UnmarshallerContext context = new JsonUnmarshallerContext(Utils.CreateStreamFromString(jsonResponse), false, webResponse);
            var response = DescribeInstancesResponseUnmarshaller.Instance.Unmarshall(context)
                as DescribeInstancesResponse;
            InstantiateClassGenerator.ValidateObjectFullyInstantiated(response);
        }

        /// <summary>
        /// Describes one or more of your instances.
        /// 
        ///  
        /// <para>
        /// If you specify one or more instance IDs, Amazon EC2 returns information for those
        /// instances. If you do not specify instance IDs, Amazon EC2 returns information for
        /// all relevant instances. If you specify an instance ID that is not valid, an error
        /// is returned. If you specify an instance that you do not own, it is not included in
        /// the returned results.
        /// </para>
        ///  
        /// <para>
        /// Recently terminated instances might appear in the returned results. This interval
        /// is usually less than one hour.
        /// </para>
        /// </summary>
        /// <param name="request">Container for the necessary parameters to execute the DescribeInstances service method.</param>
        /// 
        /// <returns>The response from the DescribeInstances service method, as returned by EC2.</returns>
        public DescribeInstancesResponse DescribeInstances(DescribeInstancesRequest request)
        {
            var marshaller = new DescribeInstancesRequestMarshaller();
            var unmarshaller = DescribeInstancesResponseUnmarshaller.Instance;

            return Invoke<DescribeInstancesRequest,DescribeInstancesResponse>(request, marshaller, unmarshaller);
        }

        /// <summary>
        /// Initiates the asynchronous execution of the DescribeInstances operation.
        /// </summary>
        /// 
        /// <param name="request">Container for the necessary parameters to execute the DescribeInstances operation on AmazonEC2Client.</param>
        /// <param name="callback">An AsyncCallback delegate that is invoked when the operation completes.</param>
        /// <param name="state">A user-defined state object that is passed to the callback procedure. Retrieve this object from within the callback
        ///          procedure using the AsyncState property.</param>
        /// 
        /// <returns>An IAsyncResult that can be used to poll or wait for results, or both; this value is also needed when invoking EndDescribeInstances
        ///         operation.</returns>
        public IAsyncResult BeginDescribeInstances(DescribeInstancesRequest request, AsyncCallback callback, object state)
        {
            var marshaller = new DescribeInstancesRequestMarshaller();
            var unmarshaller = DescribeInstancesResponseUnmarshaller.Instance;

            return BeginInvoke<DescribeInstancesRequest>(request, marshaller, unmarshaller,
                callback, state);
        }

 IAsyncResult invokeDescribeInstances(DescribeInstancesRequest describeInstancesRequest, AsyncCallback callback, object state, bool synchronized)
 {
     IRequest irequest = new DescribeInstancesRequestMarshaller().Marshall(describeInstancesRequest);
     var unmarshaller = DescribeInstancesResponseUnmarshaller.GetInstance();
     AsyncResult result = new AsyncResult(irequest, callback, state, synchronized, signer, unmarshaller);
     Invoke(result);
     return result;
 }

        /// <summary>
        /// <para>Requests a description of a set of instances.</para> <para><b>NOTE:</b>You must specify at least one of the parameters.</para> <para>
        /// <b>Required Permissions</b> : To use this action, an IAM user must have a Show, Deploy, or Manage permissions level for the stack, or an
        /// attached policy that explicitly grants permissions. For more information on user permissions, see <a href="http://docs.aws.amazon.com/opsworks/latest/userguide/opsworks-security-users.html">Managing User Permissions</a> .</para>
        /// </summary>
        /// 
        /// <param name="describeInstancesRequest">Container for the necessary parameters to execute the DescribeInstances service method on
        /// AmazonOpsWorks.</param>
        /// 
        /// <returns>The response from the DescribeInstances service method, as returned by AmazonOpsWorks.</returns>
        /// 
        /// <exception cref="T:Amazon.OpsWorks.Model.ResourceNotFoundException" />
        /// <exception cref="T:Amazon.OpsWorks.Model.ValidationException" />
        /// <param name="cancellationToken">
        ///     A cancellation token that can be used by other objects or threads to receive notice of cancellation.
        /// </param>
		public Task<DescribeInstancesResponse> DescribeInstancesAsync(DescribeInstancesRequest describeInstancesRequest, CancellationToken cancellationToken = default(CancellationToken))
        {
            var marshaller = new DescribeInstancesRequestMarshaller();
            var unmarshaller = DescribeInstancesResponseUnmarshaller.GetInstance();
            return Invoke<IRequest, DescribeInstancesRequest, DescribeInstancesResponse>(describeInstancesRequest, marshaller, unmarshaller, signer, cancellationToken);
        }

        /// <summary>
        /// Initiates the asynchronous execution of the DescribeInstances operation.
        /// <seealso cref="Amazon.EC2.IAmazonEC2.DescribeInstances"/>
        /// </summary>
        /// 
        /// <param name="request">Container for the necessary parameters to execute the DescribeInstances operation.</param>
        /// <param name="cancellationToken">
        ///     A cancellation token that can be used by other objects or threads to receive notice of cancellation.
        /// </param>
        /// <returns>The task object representing the asynchronous operation.</returns>
		public async Task<DescribeInstancesResponse> DescribeInstancesAsync(DescribeInstancesRequest request, CancellationToken cancellationToken = default(CancellationToken))
        {
            var marshaller = new DescribeInstancesRequestMarshaller();
            var unmarshaller = DescribeInstancesResponseUnmarshaller.GetInstance();
            var response = await Invoke<IRequest, DescribeInstancesRequest, DescribeInstancesResponse>(request, marshaller, unmarshaller, signer, cancellationToken)
                .ConfigureAwait(continueOnCapturedContext: false);
            return response;
        }

        IAsyncResult invokeDescribeInstances(DescribeInstancesRequest request, AsyncCallback callback, object state, bool synchronized)
        {
            var marshaller = new DescribeInstancesRequestMarshaller();
            var unmarshaller = DescribeInstancesResponseUnmarshaller.Instance;

            return Invoke(request, callback, state, synchronized, marshaller, unmarshaller, signer);
        }