public static Task<IGPResult> ExecuteToolAsync( 
   string toolPath,
   IEnumerable<string> values,
   IEnumerable<KeyValuePair<string,string>> environments,
   Nullable<CancellationToken> cancelToken,
   GPToolExecuteEventHandler callback,
   GPExecuteToolFlags flags
)

var environment = Geoprocessing.MakeEnvironmentArray(overwriteoutput: true);

      var prj = Project.Current;
      var map = MapView.Active;

      var defaultGDB = Project.Current.DefaultGeodatabasePath;

      var featLayers = map.Map.Layers.OfType<FeatureLayer>();

      var targetLayer = featLayers.ElementAt(0);  // First layer in TOC
      var joinLayer = featLayers.ElementAt(1);    // Second layer in TOC

      var outputFeatureClass = @"C:/temp/outputFC3.shp";

      // Specify the field map in Spatial Join with target and join feature class/layers in the App
      // Run Spatial Join manually - then Copy the fieldmap string from the result in Geoprocessing history and paste it for the fieldmap parameter. 
      // in this example of fieldmap, FireStations is the name of join layer
      // FireStations layer has two numeric fileds (used in Fieldmap): TYPE and NUMBER - these two fields are used in the FiedlMap
      //
      var joinLayerName = joinLayer.Name;
      var fieldMap = "TYPE 'TYPE' true true false 4 Long 0 0,Count,#,{joinLayerName},TYPE,-1,-1;NUMBER 'NUMBER' true true false 4 Long 0 0,Max,#,{joinLayerName},NUMBER,-1,-1";

      var toolParameters = Geoprocessing.MakeValueArray(targetLayer, joinLayer, outputFeatureClass, "JOIN_ONE_TO_ONE", "KEEP_COMMON", fieldMap, "INTERSECT");

      GPExecuteToolFlags executeFlags = GPExecuteToolFlags.AddOutputsToMap | GPExecuteToolFlags.GPThread | GPExecuteToolFlags.AddToHistory | GPExecuteToolFlags.RefreshProjectItems;

      IGPResult gpResult = await Geoprocessing.ExecuteToolAsync("analysis.SpatialJoin", toolParameters, environment, null, null, executeFlags);

      Geoprocessing.ShowMessageBox(gpResult.Messages, "GP Messages", gpResult.IsFailed ? GPMessageBoxStyle.Error : GPMessageBoxStyle.Default);

// get the syntax of the tool from Python window or from tool help page
string in_features = @"C:\data\data.gdb\HighwaysWeb84";
      string out_features = @"C:\data\data.gdb\HighwaysUTM";
      var param_values = Geoprocessing.MakeValueArray(in_features, out_features);

      // crate the spatial reference object to pass as an argument to management.CopyFeatures tool
      var sp_ref = await QueuedTask.Run(() => {
          return SpatialReferenceBuilder.CreateSpatialReference(26911);    // UTM 83 11N: 26911
      });

      // set output coordinate system environment           
      var environments = Geoprocessing.MakeEnvironmentArray(outputCoordinateSystem: sp_ref);
      // set environments in the 3rd parameter
      var gp_result = await Geoprocessing.ExecuteToolAsync("management.CopyFeatures", param_values, environments, null, null, GPExecuteToolFlags.AddOutputsToMap);
      
      Geoprocessing.ShowMessageBox(gp_result.Messages, "Contents", GPMessageBoxStyle.Default, "Window Title");

      //return gp_result;

var progDlg = new ProgressDialog("Running Geoprocessing Tool", "Cancel", 100, true);
      progDlg.Show();
      
      var progSrc = new CancelableProgressorSource(progDlg);

      // prepare input parameter values to CopyFeatures tool
      string input_data = @"C:\data\california.gdb\ca_highways";
      string out_workspace = ArcGIS.Desktop.Core.Project.Current.DefaultGeodatabasePath;
      string out_data = System.IO.Path.Combine(out_workspace, "ca_highways2");

      // make a value array of strings to be passed to ExecuteToolAsync
      var parameters = Geoprocessing.MakeValueArray(input_data, out_data);

      // execute the tool
      await Geoprocessing.ExecuteToolAsync("management.CopyFeatures", parameters,
          null, new CancelableProgressorSource(progDlg).Progressor, GPExecuteToolFlags.Default);

      // dialog hides itself once the execution is complete
      progDlg.Hide();

/*

   Copyright 2018 Esri

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

   See the License for the specific language governing permissions and
   limitations under the License.

*/
namespace SDKExamples
{
    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Threading.Tasks;
    using ArcGIS.Core.Geometry;
    using ArcGIS.Desktop.Core;
    using ArcGIS.Desktop.Core.Geoprocessing;
    using ArcGIS.Desktop.Mapping;
    using ArcGIS.Desktop.Framework.Threading.Tasks;

    class GeoprocessinExamples
    {
        public async void FieldMapping()
        {
      // cref: ARCGIS.DESKTOP.CORE.GEOPROCESSING.GEOPROCESSING.MAKEENVIRONMENTARRAY
      // cref: ARCGIS.DESKTOP.CORE.GEOPROCESSING.GEOPROCESSING.MakeValueArray
      // cref: ARCGIS.DESKTOP.CORE.GEOPROCESSING.GEOPROCESSING.ShowMessageBox
      // cref: ARCGIS.DESKTOP.CORE.GEOPROCESSING.GPEXECUTETOOLFLAGS
      // cref: ArcGIS.Desktop.Core.Geoprocessing.Geoprocessing.ExecuteToolAsync
      // cref: ArcGIS.Desktop.Core.Geoprocessing.Geoprocessing.ExecuteToolAsync(STRING,IENUMERABLE{STRING},IENUMERABLE{KEYVALUEPAIR{STRING,STRING}},NULLABLE{CANCELLATIONTOKEN},GPTOOLEXECUTEEVENTHANDLER,GPEXECUTETOOLFLAGS)
      // cref: ArcGIS.Desktop.Core.Geoprocessing.Geoprocessing.ExecuteToolAsync(STRING,IENUMERABLE{STRING},IENUMERABLE{KEYVALUEPAIR{STRING,STRING}},CANCELABLEPROGRESSOR,GPEXECUTETOOLFLAGS)
      #region FieldMappings

      var environment = Geoprocessing.MakeEnvironmentArray(overwriteoutput: true);

            var prj = Project.Current;
            var map = MapView.Active;

            var defaultGDB = Project.Current.DefaultGeodatabasePath;

            var featLayers = map.Map.Layers.OfType<FeatureLayer>();

            var targetLayer = featLayers.ElementAt(0);  // First layer in TOC
            var joinLayer = featLayers.ElementAt(1);    // Second layer in TOC

            var outputFeatureClass = @"C:/temp/outputFC3.shp";

            // Specify the field map in Spatial Join with target and join feature class/layers in the App
            // Run Spatial Join manually - then Copy the fieldmap string from the result in Geoprocessing history and paste it for the fieldmap parameter. 
            // in this example of fieldmap, FireStations is the name of join layer
            // FireStations layer has two numeric fileds (used in Fieldmap): TYPE and NUMBER - these two fields are used in the FiedlMap
            //
            var joinLayerName = joinLayer.Name;
            var fieldMap = "TYPE 'TYPE' true true false 4 Long 0 0,Count,#,{joinLayerName},TYPE,-1,-1;NUMBER 'NUMBER' true true false 4 Long 0 0,Max,#,{joinLayerName},NUMBER,-1,-1";

            var toolParameters = Geoprocessing.MakeValueArray(targetLayer, joinLayer, outputFeatureClass, "JOIN_ONE_TO_ONE", "KEEP_COMMON", fieldMap, "INTERSECT");

            GPExecuteToolFlags executeFlags = GPExecuteToolFlags.AddOutputsToMap | GPExecuteToolFlags.GPThread | GPExecuteToolFlags.AddToHistory | GPExecuteToolFlags.RefreshProjectItems;

            IGPResult gpResult = await Geoprocessing.ExecuteToolAsync("analysis.SpatialJoin", toolParameters, environment, null, null, executeFlags);

            Geoprocessing.ShowMessageBox(gpResult.Messages, "GP Messages", gpResult.IsFailed ? GPMessageBoxStyle.Error : GPMessageBoxStyle.Default);
            #endregion
        }

        // Setting environments, MakeEnvironmentArray
        public async void SetEnvironment()   // Task<IGPResult>
        {
      // cref: ARCGIS.DESKTOP.CORE.GEOPROCESSING.GEOPROCESSING.MAKEENVIRONMENTARRAY
      // cref: ARCGIS.DESKTOP.CORE.GEOPROCESSING.GEOPROCESSING.MakeValueArray
      // cref: ARCGIS.DESKTOP.CORE.GEOPROCESSING.GEOPROCESSING.ShowMessageBox
      // cref: ARCGIS.DESKTOP.CORE.GEOPROCESSING.GPEXECUTETOOLFLAGS
      // cref: ArcGIS.Desktop.Core.Geoprocessing.Geoprocessing.ExecuteToolAsync
      // cref: ArcGIS.Desktop.Core.Geoprocessing.Geoprocessing.ExecuteToolAsync(STRING,IENUMERABLE{STRING},IENUMERABLE{KEYVALUEPAIR{STRING,STRING}},NULLABLE{CANCELLATIONTOKEN},GPTOOLEXECUTEEVENTHANDLER,GPEXECUTETOOLFLAGS)
      // cref: ArcGIS.Desktop.Core.Geoprocessing.Geoprocessing.ExecuteToolAsync(STRING,IENUMERABLE{STRING},IENUMERABLE{KEYVALUEPAIR{STRING,STRING}},CANCELABLEPROGRESSOR,GPEXECUTETOOLFLAGS)
      #region Setting environments, MakeEnvironmentArray
      // get the syntax of the tool from Python window or from tool help page
      string in_features = @"C:\data\data.gdb\HighwaysWeb84";
            string out_features = @"C:\data\data.gdb\HighwaysUTM";
            var param_values = Geoprocessing.MakeValueArray(in_features, out_features);

            // crate the spatial reference object to pass as an argument to management.CopyFeatures tool
            var sp_ref = await QueuedTask.Run(() => {
                return SpatialReferenceBuilder.CreateSpatialReference(26911);    // UTM 83 11N: 26911
            });

            // set output coordinate system environment           
            var environments = Geoprocessing.MakeEnvironmentArray(outputCoordinateSystem: sp_ref);
            // set environments in the 3rd parameter
            var gp_result = await Geoprocessing.ExecuteToolAsync("management.CopyFeatures", param_values, environments, null, null, GPExecuteToolFlags.AddOutputsToMap);
            
            Geoprocessing.ShowMessageBox(gp_result.Messages, "Contents", GPMessageBoxStyle.Default, "Window Title");

            //return gp_result;

            #endregion
        }

        public async void ProgressDialogExample()
        {

      // cref: ARCGIS.DESKTOP.FRAMEWORK.THREADING.TASKS.PROGRESSDIALOG
      // cref: ARCGIS.DESKTOP.FRAMEWORK.THREADING.TASKS.PROGRESSDIALOG.#ctor
      // cref: ARCGIS.DESKTOP.CORE.GEOPROCESSING.GEOPROCESSING.MakeValueArray
      // cref: ArcGIS.Desktop.Core.Geoprocessing.Geoprocessing.ExecuteToolAsync
      // cref: ArcGIS.Desktop.Core.Geoprocessing.Geoprocessing.ExecuteToolAsync(STRING,IENUMERABLE{STRING},IENUMERABLE{KEYVALUEPAIR{STRING,STRING}},NULLABLE{CANCELLATIONTOKEN},GPTOOLEXECUTEEVENTHANDLER,GPEXECUTETOOLFLAGS)
      // cref: ArcGIS.Desktop.Core.Geoprocessing.Geoprocessing.ExecuteToolAsync(STRING,IENUMERABLE{STRING},IENUMERABLE{KEYVALUEPAIR{STRING,STRING}},CANCELABLEPROGRESSOR,GPEXECUTETOOLFLAGS)
      #region Running Geoprocessing Tool with ProgressDialog

      var progDlg = new ProgressDialog("Running Geoprocessing Tool", "Cancel", 100, true);
            progDlg.Show();
            
            var progSrc = new CancelableProgressorSource(progDlg);

            // prepare input parameter values to CopyFeatures tool
            string input_data = @"C:\data\california.gdb\ca_highways";
            string out_workspace = ArcGIS.Desktop.Core.Project.Current.DefaultGeodatabasePath;
            string out_data = System.IO.Path.Combine(out_workspace, "ca_highways2");

            // make a value array of strings to be passed to ExecuteToolAsync
            var parameters = Geoprocessing.MakeValueArray(input_data, out_data);

            // execute the tool
            await Geoprocessing.ExecuteToolAsync("management.CopyFeatures", parameters,
                null, new CancelableProgressorSource(progDlg).Progressor, GPExecuteToolFlags.Default);

            // dialog hides itself once the execution is complete
            progDlg.Hide();

            #endregion
        }


        public async void ExecuteEBK()
        {
            // cref: gp_events;ArcGIS.Desktop.Core.Geoprocessing.Geoprocessing.ExecuteToolAsync(System.String,System.Collections.Generic.IEnumerable{System.String},System.Collections.Generic.IEnumerable{System.Collections.Generic.KeyValuePair{System.String,System.String}},System.Nullable{System.Threading.CancellationToken},ArcGIS.Desktop.Core.Geoprocessing.GPToolExecuteEventHandler,ArcGIS.Desktop.Core.Geoprocessing.GPExecuteToolFlags)
            // cref: gp_events;ArcGIS.Desktop.Core.Geoprocessing.GPToolExecuteEventHandler
            #region GPTool Execute Event Handler

            System.Threading.CancellationTokenSource _cts;

            string ozone_points = @"C:\data\ca_ozone.gdb\O3_Sep06_3pm";

            string[] args = { ozone_points, "OZONE", "", "in_memory\\raster", "300",
                                "EMPIRICAL", "300", "5", "5000",
                                "NBRTYPE=StandardCircular RADIUS=310833.272442914 ANGLE=0 NBR_MAX=10 SECTOR_TYPE=ONE_SECTOR",
                                "PREDICTION", "0.5", "EXCEED", "", "K_BESSEL" };

            string tool_path = "ga.EmpiricalBayesianKriging";

            _cts = new System.Threading.CancellationTokenSource();

            var result = await Geoprocessing.ExecuteToolAsync(tool_path, args, null, _cts.Token,
                (event_name, o) =>  // implement delegate and handle events
                {
                    switch (event_name)
                    {
                        case "OnValidate": // stop execute if any warnings
                            if ((o as IGPMessage[]).Any(it => it.Type == GPMessageType.Warning))
                                _cts.Cancel();
                            break;

                        case "OnProgressMessage":
                            string msg = string.Format("{0}: {1}", new object[] { event_name, (string)o });
                            System.Windows.MessageBox.Show(msg);
                            _cts.Cancel();
                            break;

                        case "OnProgressPos":
                            string msg2 = string.Format("{0}: {1} %", new object[] { event_name, (int)o });
                            System.Windows.MessageBox.Show(msg2);
                            _cts.Cancel();
                            break;
                    }
                });

            var ret = result;
            _cts = null;

            #endregion
        }

        public async void ShowMessageBox()
        {
      // cref: ArcGIS.Desktop.Core.Geoprocessing.Geoprocessing.ExecuteToolAsync
      // cref: ArcGIS.Desktop.Core.Geoprocessing.Geoprocessing.ExecuteToolAsync(STRING,IENUMERABLE{STRING},IENUMERABLE{KEYVALUEPAIR{STRING,STRING}},NULLABLE{CANCELLATIONTOKEN},GPTOOLEXECUTEEVENTHANDLER,GPEXECUTETOOLFLAGS)
      // cref: ArcGIS.Desktop.Core.Geoprocessing.Geoprocessing.ExecuteToolAsync(STRING,IENUMERABLE{STRING},IENUMERABLE{KEYVALUEPAIR{STRING,STRING}},CANCELABLEPROGRESSOR,GPEXECUTETOOLFLAGS)
      // cref: message_box;ArcGIS.Desktop.Core.Geoprocessing.Geoprocessing.ShowMessageBox(System.Collections.Generic.IEnumerable{ArcGIS.Desktop.Core.Geoprocessing.IGPMessage},System.String,ArcGIS.Desktop.Core.Geoprocessing.GPMessageBoxStyle,System.String,System.String,ArcGIS.Desktop.Framework.Contracts.ViewModelBase)
      #region Geoprocessing specialized MessageBox
      var gp_result = await Geoprocessing.ExecuteToolAsync("management.GetCount", Geoprocessing.MakeValueArray(@"C:\data\f.gdb\hello"));
            // this icon shows up left of content_header
            string icon_src = @"C:\data\Icons\ModifyLink32.png";
            Geoprocessing.ShowMessageBox(gp_result.Messages, "Content Header", GPMessageBoxStyle.Error, "Window Title", icon_src);
            #endregion
        }

        private void OpenBufferToolDialog()
        {
      // cref: ARCGIS.DESKTOP.CORE.GEOPROCESSING.GEOPROCESSING.MakeValueArray
      // cref: open_dialog;ArcGIS.Desktop.Core.Geoprocessing.Geoprocessing.OpenToolDialog(System.String,System.Collections.Generic.IEnumerable{System.String},System.Collections.Generic.IEnumerable{System.Collections.Generic.KeyValuePair{System.String,System.String}},System.Boolean,ArcGIS.Desktop.Core.Geoprocessing.GPToolExecuteEventHandler)
      #region Geoprocessing Open ToolDialog
      string input_points = @"C:\data\ca_ozone.gdb\ozone_points";
            string output_polys = @"C:\data\ca_ozone.gdb\ozone_buff";
            string buffer_dist = "2000 Meters";

            var param_values = Geoprocessing.MakeValueArray(input_points, output_polys, buffer_dist);

            Geoprocessing.OpenToolDialog("analysis.Buffer", param_values);
            #endregion
        }
    }

}

var gp_result = await Geoprocessing.ExecuteToolAsync("management.GetCount", Geoprocessing.MakeValueArray(@"C:\data\f.gdb\hello"));
      // this icon shows up left of content_header
      string icon_src = @"C:\data\Icons\ModifyLink32.png";
      Geoprocessing.ShowMessageBox(gp_result.Messages, "Content Header", GPMessageBoxStyle.Error, "Window Title", icon_src);

// get the model tool's parameter syntax from the model's help
string input_roads = @"C:\data\Input.gdb\PlanA_Roads";
      string buff_dist_field = "Distance";   // use values from a field
      string input_vegetation = @"C:\data\Input.gdb\vegetation";
      string output_data = @"C:\data\Output.gdb\ClippedFC2";

      // the model name is ExtractVegetation
      string tool_path = @"C:\data\MB\Models.tbx\ExtractVegetation";

      var args = Geoprocessing.MakeValueArray(input_roads, buff_dist_field, input_vegetation, output_data);

      var result = await Geoprocessing.ExecuteToolAsync(tool_path, args);

var parameters = Geoprocessing.MakeValueArray(@"C:\data\data.gdb\HighwaysUTM11", @"C:\data\data.gdb\Highways_extent");
      var ext = Geoprocessing.MakeEnvironmentArray(extent: "460532 3773964 525111 3827494");
      var gp_result = await Geoprocessing.ExecuteToolAsync("management.CopyFeatures", parameters, ext);

// However, settings in Pro App's Geoprocessing Options will override option set in code
// for example, in Pro App's Options > Geoprocessing dialog, if you check 'Add output datasets to an open map'
// then the output WILL BE added to history overriding settings in code
var CopyfeaturesParams = Geoprocessing.MakeValueArray("C:\\data\\Input.gdb\\PlanA_Roads", "C:\\data\\Input.gdb\\Roads_copy");
      IGPResult gpResult = await Geoprocessing.ExecuteToolAsync("management.CopyFeatures", CopyfeaturesParams, null, null, null, GPExecuteToolFlags.None);

// However, settings in Pro App's Geoprocessing Options will override option set in code
// for example, if in Options > Geoprocessing dialog, if you uncheck 'Write geoprocessing operations to Geoprocessing History'
// then the output will not be added to history.
var args2 = Geoprocessing.MakeValueArray("C:\\data\\Vegetation.shp", "NewField", "TEXT");
      var result2 = await Geoprocessing.ExecuteToolAsync("management.AddField", args2, null, null, null, GPExecuteToolFlags.AddToHistory);

//The data referenced in this snippet can be downloaded from the arcgis-pro-sdk-community-samples repo
//https://github.com/Esri/arcgis-pro-sdk-community-samples
async Task<IGPResult> CreateRings(EditingTemplate currentTemplate)
      {
          var paramsArray = Geoprocessing.MakeValueArray(currentTemplate.MapMember.Name,
                      @"C:\Data\FeatureTest\FeatureTest.gdb\Points_MultipleRingBuffer",
                      new List<string> { "1000", "2000" }, "Meters", "Distance",
                      "ALL", "FULL");

          IGPResult ringsResult = await Geoprocessing.ExecuteToolAsync("Analysis.MultipleRingBuffer", paramsArray);
          var messages = string.IsNullOrEmpty(gpResult.ReturnValue)
                  ? $@"Error in gp tool: {gpResult.ErrorMessages}"
                  : $@"Ok: {gpResult.ReturnValue}";

          return ringsResult;
      }

//The data referenced in this snippet can be downloaded from the arcgis-pro-sdk-community-samples repo
//https://github.com/Esri/arcgis-pro-sdk-community-samples
string in_data = @"C:\tools\data.gdb\cities";
      string cities_buff = @"E:\data\data.gdb\cities_2km";

      var valueArray = Geoprocessing.MakeValueArray(in_data, cities_buff, "2000 Meters");

      // to let the GP tool run asynchronously without blocking the main thread
      // use the GPThread option of GPExecuteToolFlasgs
      //
      GPExecuteToolFlags flags = GPExecuteToolFlags.GPThread;  // instruct the tool run non-blocking GPThread
      IGPResult bufferResult = await Geoprocessing.ExecuteToolAsync("Analysis.Buffer", valueArray, null, null, null, flags);

var environments = Geoprocessing.MakeEnvironmentArray(overwriteoutput: true);

      string toolName = "Snap_edit";  // or use edit.Snap

      // Snap tool takes multiple inputs each of which has
      // Three (3) parts: a feature class or layer, a string value and a distance
      // Each part is separated by a semicolon - you can get example of sytax from the tool documentation page
      var snapEnv = @"'C:/SnapProject/fgdb.gdb/line_1' END '2 Meters';'C:/SnapProject/fgdb.gdb/points_1' VERTEX '1 Meters';'C:/SnapProject/fgdb.gdb/otherline_1' END '20 Meters'";

      var infc = @"C:/SnapProject/fgdb.gdb/poly_1";

      var snapParams = Geoprocessing.MakeValueArray(infc, snapEnv);

      GPExecuteToolFlags tokens = GPExecuteToolFlags.RefreshProjectItems | GPExecuteToolFlags.GPThread | GPExecuteToolFlags.AddToHistory;

      IGPResult snapResult = await Geoprocessing.ExecuteToolAsync(toolName, parameters, environments, null, null, tokens);

      //return gpResult;

string tool2 = "analysis.Buffer";
List<MapPoint> list = new List<MapPoint>();
list.Add(MapPointBuilderEx.CreateMapPoint(1.0, 1.0));
list.Add(MapPointBuilderEx.CreateMapPoint(1.0, 2.0));
list.Add(MapPointBuilderEx.CreateMapPoint(2.0, 2.0));
list.Add(MapPointBuilderEx.CreateMapPoint(2.0, 1.0));

Multipoint multiPoint = MultipointBuilderEx.CreateMultipoint(list);
var spatial_ref = SpatialReferenceBuilder.CreateSpatialReference(3857);
var args3 = await QueuedTask.Run(() =>
{
    return Geoprocessing.MakeValueArray(multiPoint, "memory\\Buffers", "800 meters");
});
var env1 = Geoprocessing.MakeEnvironmentArray(outputCoordinateSystem: spatial_ref);
var messages = new List<string>(); // list to collect all output messages
var cts = new CancellationTokenSource();
await Geoprocessing.ExecuteToolAsync(tool2, args3, env1, cts.Token);
    

string openProjectPath = @"D\DATA\IGPHistoryItemTestProject\IGPHistoryItemTestProject.aprx";
await Project.OpenAsync(openProjectPath); 
MapProjectItem mapProjItem = Project.Current.GetItems<MapProjectItem>().FirstOrDefault(item => item.Name.Equals("Map", StringComparison.CurrentCultureIgnoreCase));

var map = await QueuedTask.Run(() => mapProjItem.GetMap());
var ftrLayer = map.Layers[0] as FeatureLayer;
string tool1 = "management.GetCount";     
var args1 = Geoprocessing.MakeValueArray(ftrLayer);
var env = Geoprocessing.MakeEnvironmentArray(overwriteoutput: true);          
GPExecuteToolFlags executeFlags = GPExecuteToolFlags.AddToHistory;
var t = await Geoprocessing.ExecuteToolAsync(tool1, args1,env,null,null,executeFlags);

IEnumerable<IGPHistoryItem> hisItems = Project.Current.GetProjectItemContainer(Geoprocessing.HistoryContainerKey) as IEnumerable<IGPHistoryItem>;        

String hitemID="";
String hitemToolPath="" ;
IGPResult hitemGPResult=null;
DateTime hitemTimeStamp;

foreach (var hitem in hisItems)
{
    // common IGPHistoryItem and Item properties
    hitemID = (hitem as Item).ID;
    hitemToolPath = hitem.ToolPath;
    hitemGPResult = hitem.GPResult;
    hitemTimeStamp = hitem.TimeStamp;
}

ArcGIS.Desktop.Core.Events.GPExecuteToolEvent.Subscribe(e =>
      {
          string id = e.ID;                   // Same as history ID
          if (e.IsStarting == false)  // Execute completed
              _ = e.GPResult.ReturnValue;
          System.Windows.MessageBox.Show("event triggered.");
      });
await Geoprocessing.ExecuteToolAsync("management.GetCount", Geoprocessing.MakeValueArray(@"c:\shape_file.shp"));

var tool_name = "analysis.Clip";
var extent = MapView.Active.Extent;
var sel_layer = MapView.Active.Map.GetLayersAsFlattenedList()
                  .OfType<FeatureLayer>().FirstOrDefault(l => l.Name == "GreatLakes");
if (sel_layer == null) return;

var gdb = Project.Current.DefaultGeodatabasePath;
var out_fc = System.IO.Path.Combine(gdb, "clipped_lakes_out");

var val_array = await QueuedTask.Run(() =>
{

  var rect = GeometryEngine.Instance.Scale(extent, extent.Center, 0.5, 0.5) as Envelope;
  var clip_poly = PolygonBuilderEx.CreatePolygon(rect, rect.SpatialReference);

  //Add the geometry to a list before calling MakeValueArray
  //Envelope and Geometry types are supported
  var geom = new List<object>() { clip_poly };
  return Geoprocessing.MakeValueArray(new object[] { sel_layer, geom, out_fc });

});
Geoprocessing.ExecuteToolAsync(tool_name, val_array,
  null, null, null, GPExecuteToolFlags.InheritGPOptions);