Handle Events from WinHttpRequest - events

Question

A program I use runs .VBS scripts
So, in VBScript how can you handle the OnResponseFinished event for a WinHttpRequest object?
Set oHTTP = CreateObject("WinHttp.WinHttpRequest.5.1")
oHTTP.Open "GET", "http://www.google.com", True
oHTTP.Send

Answer 1

I was trying to get some code executed when the winhttp response comes (using VBScript inside HTA file). You may consider putting your event code right after the send. Using the following code, the user interface does not hang when waiting for the response:
Set objHTTP = CreateObject("WinHttp.WinHttpRequest.5.1")
objHTTP.Open "GET", "http://www.google.com", True
objHTTP.Send
objHTTP.WaitForResponse 'pauses execution, but does not hang UI
'from now on, execution only takes effect after completion of the response:
msgbox objHTTP.responseText 'an example of what can be done with the response
This seems to be the same as synchronous winhttp for script files, which can be what you are looking for. So, the only difference may be noticed when using an user interface.

Answer 2

Change the third paramater in the call to the Open method to false. Then place the code you would have in OnResponseFinished after the call to send.

Answer 3

Use WScript's CreateObject not the built in one for event handler.
Set oHTTP = WScript.CreateObject(
"WinHttp.WinHttpRequest.5.1",
"oHTTP_"
)

Answer 4

I'll admit his isn't a great answer, but the usual way to register VBScript events is to use the GetRef function to get a reference to the event handler, eg with an MSXML2.XMLHTTP object:
Set oHTTP = CreateObject("MSXML2.XMLHTTP")
oHTTP.Open "GET", "http://www.google.com", True
oHTTP.OnReadyStateChange = GetRef("oHTTP_OnReadyStateChange")
Sub oHTTP_OnReadyStateChange
' do something
End sub
oHTTP.Send
The trouble is, I tried it for your code, ie
Set oHTTP = CreateObject("WinHttp.WinHttpRequest.5.1")
oHTTP.Open "GET", "http://www.google.com", True
oHTTP.OnResponseFinished = GetRef("oHTTP_OnResponseFinished")
Sub oHTTP_OnResponseFinished
' do something
End sub
oHTTP.Send
and it didn't work, getting the error
Object doesn't support this property or method: 'oHTTP.OnResponseFinished'
but perhaps this can give you a starting point , or maybe you can use the MSXML2 library instead?
Just updating this answer with the other way of handling COM events - use the second parameter for the CreateObject function which allows you to specify the function prefix which connects functions to objects, eg
Set oHTTP = CreateObject("WinHttp.WinHttpRequest.5.1", "oHTTP_")
oHTTP.Open "GET", "http://www.google.com", True
Sub oHTTP_OnResponseFinished
' do something
End sub
oHTTP.Send
unfortunately, this doesn't work either - it must be that the IWinHttpRequestEvents interface is inaccessible

Answer 5

I checked the Windows Registry and there appears to be a number of Microsoft objects that do nearly the same thing:
Microsoft.XMLHTTP {ED8C108E-4349-11D2-91A4-00C04F7969E8}
MSXML2.XMLHTTP {F6D90F16-9C73-11D3-B32E-00C04F990BB4}
WinHttp.WinHttpRequest.5.1 {2087c2f4-2cef-4953-a8ab-66779b670495}
MSXML2.ServerXMLHTTP {AFBA6B42-5692-48EA-8141-DC517DCF0EF1}
What works for me is Microsoft.ServerXMLHTTP which allows setting of the onreadystatechange in VBScript. The "MSXML2.ServerXMLHTTP" handles redirecting websites (e.g. google.com) which makes it a better choice over "Microsoft.XMLHTTP".
Dim xmlhttp ' global so can be accessed in OnStateChange
Sub OnStateChange
If xmlhttp.readystate = 4 Then
' React to xmlhttp.responseText
MsgBox xmlhttp.responseText
End If
End Sub
Set xmlhttp = CreateObject("Microsoft.XMLHTTP")
xmlhttp.open "GET", "http://www.google.com/", true
xmlhttp.onreadystatechange = GetRef("OnStateChange")
xmlhttp.send
' do something else whilst xmlhttp is running in the background
MsgBox "Pausing so that OnStateChange can fire!"

Answer 6

It does need seem to be possible according to this (go to remarks) you can only access the error state with Err. Microsoft's documentation is lousy.

Answer 7

I found that I can get this to work Asynchronously by using the 'waitForResponse' with parameter '0' for the timeout method as a flag.
IE:
oHTTP.Open "GET", "http://www.google.com", True
oHTTP.Send
Do While oHTTP.waitForResponse(0) = False
'do stuff while waiting for it to be done
WScript.Sleep 200 'sleep for 0.2 seconds between checks as not waste CPU
DoEvents
Loop
'Once the loop is exited, the response is finished
MsgBox oHTTP.ResponseText