Engine调用gp服务如何获得JobID?

public void SampleGeneratingGeoprocessingResults() 

{ 

// Initialize the geoprocessor. 

Geoprocessor GP = new Geoprocessor(); 

// Add the BestPath toolbox. 

GP.AddToolbox(@http://flame7/arcgis/services;GP/Bestpathtoolbox); 

// Input values are layers on the server. 

IVariantArray parameters = new VarArrayClass(); 

parameters.Add(@source); 

parameters.Add(@destination); 

// Execute the server tool. 

IGeoProcessorResult2 result; 

result = (IGeoProcessorResult2)GP.Execute(CalculateBestPath, parameters, null); 

// Check the job status. 

while (result.Status != esriJobStatus.esriJobSucceeded) 

{ 

Console.WriteLine(result.Status.ToString()); 

System.Threading.Thread.Sleep(100); 

} 

// If the job succeeded, retrieve the feature result. 

if (result.Status == esriJobStatus.esriJobSucceeded) 

{ 

MessageBox.Show(result.ResultID.ToString()); 

} 

// Print the resulting messages. 

for (int Count = 0; Count <= result.MessageCount - 1; Count++) 

{ 

Console.WriteLine(result.GetMessage(Count)); 

} 

}