/// <summary>Performs request for climate parameter</summary>
/// <param name="request">Request to perform</param>
/// <param name="progressReport">Handler to call periodically with information about request</param>
/// <param name="cacheFileName">Optional file name with Dmitrov dataset (CSV or NetCDF) to cache results. If specified file exists DataSet from it is returned and
/// no actual request is made</param>
/// <returns>Task that results in DataSet with climate parameter values, optional uncertainty and provenance information</returns>
public static Task <DataSet> FetchAsync(IFetchRequest request, Action <FetchStatus> progressReport = null, string cacheFileName = null)
{
if (String.IsNullOrEmpty(cacheFileName))
{
return(Instance.FetchAsync(request, progressReport));
}
else
{
if (File.Exists(cacheFileName))
{
try
{
return(Task.FromResult <DataSet>(DataSet.Open(cacheFileName))); // Try to open cached data set
}
catch (Exception exc)
{
Trace.WriteLine(String.Format("Cached response is not found at {0}. Performing request...", cacheFileName));
}
}
return(Instance.FetchAsync(request, progressReport).ContinueWith <DataSet>(t => {
var result = t.Result;
try
{
result = result.Clone(cacheFileName);
}
catch (Exception exc2)
{
Trace.WriteLine(String.Format("Error writing cached response to {0}: {1}", cacheFileName, exc2.Message));
}
return result;
}, TaskContinuationOptions.OnlyOnRanToCompletion));
}
}
