Running Async functions

[lsavidge]

I have a Windows form application. It is called via the task scheduler in Windows. If I pass it a command line parameter it runs without the form loading. My problem is that at the end I need to close the form. The trouble is I am calling a web service and posting data to it in a async task. During the send, the task continues and the application finishes before the async web service call responds. So I have this constructor for the form load only when a specific command line parameter is passed in.

public frmForwarder(AppParams appParams)
{
InitializeComponent();
this.FormClosing += frmForwarder_FormClosing;
LoadSettings();
logger.WriteLog(Resources.sLogLineBreak);
logger.WriteLog("Headless mode");

RunHeadless();

logger.WriteLog("End of run");
logger.WriteLog(Resources.sLogLineBreak);

if (bHidden)
{
SaveSettings();
//Environment.Exit(0);
}
}



If I uncomment the Environment.Exit(0); the application quits before RunHeadless has completed. The code for RunHeadless is and the RunUpdateFunction here:

private async void RunHeadless()
{
Hide();
bHidden = true;
iReturnCode = OpenDB();

if (iReturnCode == 0)
{
await RunUpdateFunction("customer");
}
}

private async Task RunUpdateFunction(string psEndFunction)
{
logger.WriteLog("Running update function: " + psEndFunction);

switch (psEndFunction.ToLower())
{
case "customer":
CreatePMCustomer();
iReturnCode = await SendCustomer(new HttpMethod("POST"), Resources.sEndpointURL + Resources.sEndpointCustomerUpdate, pmCustomer);
logger.WriteLog("Return code from customer update: " + iReturnCode.ToString());
break;
}
}



You can ignore CreatePMCustomer as that just creates the XML objects that I need to send. The SendCustomer function is here:

public async Task<int> SendCustomer(HttpMethod method, string requestUri, TMCustomerXML payload = null)
{
HttpContent content = null;
string sTMResponse = "";
int statusNumber = 200; // Assume Ok
XmlSerializer xmlSerializer = new XmlSerializer(payload.GetType());
importResult xmlImportResult = new importResult();
XmlSerializer xmlResponse = new XmlSerializer(xmlImportResult.GetType());
StringWriter textWriter = new Utf8StringWriter();
string sResponseText = "";

// Serialize the payload if one is present
if (payload != null)
{
xmlSerializer.Serialize(textWriter, payload);
string payloadString = textWriter.ToString();
content = new StringContent(payloadString, Encoding.UTF8, "application/xml");
}

using (HttpClientHandler httpClientHandler = new HttpClientHandler { Credentials = new NetworkCredential(sTMLogon, sTMPassword) })
using (HttpClient httpClient = new HttpClient(httpClientHandler))
{
HttpRequestMessage request = new HttpRequestMessage(method, requestUri)
{
Content = content
};

try
{
HttpResponseMessage response = await httpClient.SendAsync(request);

sTMResponse = await response.Content.ReadAsStringAsync();
xmlImportResult = (importResult)xmlResponse.Deserialize(new StringReader(sTMResponse));

statusNumber = (int)response.StatusCode;
sResponseText = "HTTP Response: " + response.ReasonPhrase + " - Response status: " + xmlImportResult.status;
lblStatus.Text = sResponseText;
logger.WriteLog(sResponseText);

switch (statusNumber)
{
case 200:
break;
case 404:
break;
}
}
catch (Exception ex)
{
lblStatus.Text = ex.Message;
}
}

return statusNumber;
}



If I comment out the Environment.Exit(0) the form will load and wait and things work. If I uncomment it it quits before the httpClient.SendAsync(request) has had time to get the response.

How can I get the code to wait for the response and not do it asynchronously so the response comes back and the application can close normally after the response has come back?

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