VBScript Abort Method
last modified April 9, 2025
The Abort method in VBScript is used to terminate an asynchronous
HTTP request made through XMLHTTP or ServerXMLHTTP
objects. It immediately stops the ongoing request and releases associated
resources. This method is crucial for managing long-running or stuck HTTP
requests in scripts.
Abort helps prevent script hangs when dealing with unreliable network
connections. It's typically used in timeout scenarios or user-initiated
cancellations. This tutorial covers Abort with practical examples
to demonstrate its proper usage.
Abort Method Overview
The Abort method belongs to both XMLHTTP and
ServerXMLHTTP objects in VBScript. It terminates any pending
asynchronous HTTP request immediately. The method takes no parameters and
returns no value.
Key features include immediate request termination and resource cleanup. After
calling Abort, the request's readyState becomes 0
(UNSENT). Proper error handling should be implemented when using this method.
Basic Request Abort
This example demonstrates the simplest use of Abort to cancel an
HTTP request. It shows how to create an XMLHTTP request and abort it before
completion. The script includes basic error handling.
On Error Resume Next
Set xmlhttp = CreateObject("MSXML2.XMLHTTP")
xmlhttp.Open "GET", "http://example.com/api", True
xmlhttp.Send
' Simulate needing to abort the request
WScript.Sleep 1000
xmlhttp.Abort
If Err.Number <> 0 Then
WScript.Echo "Error: " & Err.Description
Else
WScript.Echo "Request aborted successfully"
End If
Set xmlhttp = Nothing
The script creates an asynchronous GET request and aborts it after 1 second. The
Abort method stops the request regardless of its current state.
Error handling ensures any issues during the process are caught and reported.
Timeout-Based Abort
This example shows how to implement a timeout mechanism using Abort.
It cancels the request if it takes too long to complete. This pattern is useful
for unreliable network connections.
On Error Resume Next
Set xmlhttp = CreateObject("MSXML2.XMLHTTP")
xmlhttp.Open "GET", "http://slow.example.com/api", True
xmlhttp.Send
startTime = Timer
timeout = 5 ' seconds
Do While xmlhttp.readyState < 4
If Timer - startTime > timeout Then
xmlhttp.Abort
WScript.Echo "Request timed out after " & timeout & " seconds"
Exit Do
End If
WScript.Sleep 100
Loop
If xmlhttp.readyState = 4 And xmlhttp.status = 200 Then
WScript.Echo "Request completed: " & xmlhttp.responseText
End If
Set xmlhttp = Nothing
The script monitors the request's duration and aborts if it exceeds 5 seconds. The loop checks both the elapsed time and request state. This approach prevents indefinite waiting for slow or unresponsive servers.
User-Initiated Abort
This example demonstrates aborting a request based on user input. It shows how to
integrate Abort with user interaction. The script uses a simple
message box for demonstration.
Set xmlhttp = CreateObject("MSXML2.XMLHTTP")
Set wshShell = CreateObject("WScript.Shell")
xmlhttp.Open "GET", "http://example.com/largefile", True
xmlhttp.Send
' Simulate user choosing to cancel
userChoice = wshShell.Popup("Cancel download?", 5, "Download in progress", 4 + 32)
If userChoice = 6 Then ' User clicked Yes
xmlhttp.Abort
WScript.Echo "Download cancelled by user"
Else
WScript.Echo "Download continuing..."
End If
Set xmlhttp = Nothing
Set wshShell = Nothing
The script starts a download and presents a cancellation dialog after 5 seconds.
If the user chooses to cancel, Abort terminates the request. This
pattern is useful for long-running operations where user control is needed.
Abort in Error Handling
This example shows proper error handling when using Abort. It
demonstrates cleaning up resources after an aborted request. The script includes
comprehensive error checking.
On Error Resume Next
Set xmlhttp = CreateObject("MSXML2.XMLHTTP")
If Err.Number <> 0 Then
WScript.Echo "Error creating object: " & Err.Description
WScript.Quit 1
End If
xmlhttp.Open "GET", "http://invalid.url", True
xmlhttp.Send
' Simulate needing to abort
WScript.Sleep 2000
xmlhttp.Abort
If Err.Number <> 0 Then
WScript.Echo "Error during request: " & Err.Description
Else
WScript.Echo "Request aborted cleanly"
End If
Set xmlhttp = Nothing
The script demonstrates robust error handling around the Abort
operation. Each step checks for errors, and resources are properly cleaned up.
This approach ensures stability even when requests fail or are cancelled.
Abort with ServerXMLHTTP
This example shows Abort usage with ServerXMLHTTP,
which is better suited for server-side scripts. The pattern is similar to
XMLHTTP but with server-specific features.
On Error Resume Next
Set serverHttp = CreateObject("MSXML2.ServerXMLHTTP.6.0")
serverHttp.Open "POST", "http://api.example.com/process", True
serverHttp.SetRequestHeader "Content-Type", "application/json"
serverHttp.Send "{""data"":""value""}"
' Abort if not completed within 3 seconds
startTime = Timer
Do While serverHttp.readyState < 4
If Timer - startTime > 3 Then
serverHttp.Abort
WScript.Echo "Server request timed out"
Exit Do
End If
WScript.Sleep 100
Loop
If serverHttp.readyState = 4 Then
WScript.Echo "Response: " & serverHttp.responseText
End If
Set serverHttp = Nothing
The script uses ServerXMLHTTP for a POST request with a JSON
payload. It implements a timeout that aborts the request after 3 seconds. This
example shows the same Abort behavior across different HTTP client
objects.
Source
In this article, we have explored the Abort method in VBScript,
covering its usage and practical applications. From simple cancellations to
complex timeout scenarios, these examples demonstrate reliable HTTP request
management. With this knowledge, you can enhance your scripts with proper
request cancellation capabilities.
Author
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