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URLSaveAsynchronous["url","file",func]

performs a download to "file" in the background, calling func when an event is raised.

Details and Options
Details and Options Details and Options
Examples  
Basic Examples  
Options  
"Method"  
"Parameters"  
"VerifyPeer"  
Show More Show More
"Username"  
"Password"  
"UserAgent"  
"Cookies"  
"StoreCookies"  
"Headers"  
"BodyData"  
"MultipartData"  
"ReadTimeout"  
"ConnectTimeout"  
"Progress"  
"UserData"  
Properties & Relations  
See Also
History
Cite this Page

URLSaveAsynchronous

URLSaveAsynchronous is being phased out in favor of URLDownloadSubmit, which was introduced experimentally in Version 11.2.

URLSaveAsynchronous["url","file",func]

performs a download to "file" in the background, calling func when an event is raised.

Details and Options

  • Types of events that may be raised:
  • "data"returns an empty list; can be used to indicate the connection has completed
    "progress"returns information about the current connection of the form {dlnow,dltotal,ulnow,ultotal}
    "error"indicates that an error occurred while attempting to connect to the URL
    "headers"headers received from the web server
    "cookies"a list of all known cookies
    "statuscode"the status code returned by the server
  • The following options can be given:
  • Method"GET"method to use for request
    "Parameters" {}parameters to be sent for the request
    "Body"""contents of message body to be sent
    "MultipartElements"{}list of multipart data elements to send
    "Username" ""username to use for the request
    "Password" ""password to use for the request
    "Headers" {}headers to be manually sent to the HTTP server
    "Cookies" Automaticcookies to pass to the server
    "StoreCookies" Truewhether to store received cookies
    "VerifyPeer" Trueverify authenticity using SSL certificates
    "UserAgent" Automaticuser agent string to send
    "ReadTimeout" 0time to allow for uploading or downloading data
    "ConnectTimeout" 0time to allow for connecting to the server
    "Progress" Falsewhether to raise a "progress" event
    "Transfer"Automaticif Automatic, the "data" event returns once and returns all the data downloaded; if "Chunks", the "data" event is raised multiple times with the data downloaded since the last event was raised
    "UserData" Noneany expression passed to this option will be stored for use of the AsynchronousTaskObject inside the event function; the data can be found by checking the options of AsynchronousTaskObject passed to the event function
    BinaryFormatTruewhether to avoid textual interpretation of newlines or other data
    "FollowRedirects"Truewhether to follow redirects
  • When an event is raised, the event function passed to URLSaveAsynchronous will be executed. The event functions will be passed three arguments, the AsynchronousTaskObject, the event name, and the data received from the event. Event functions are the only method for handling data received from URLSaveAsynchronous.

Examples

open all close all

Basic Examples  (1)

Monitor progress while downloading the contents of a URL to a file:

Wolfram Language code: url = "http://exampledata.wolfram.com/10mb.dat"; progress = 0.; progFunction[_, "progress", {dlnow_, dltotal_, _, _}] := Quiet[progress = dlnow / dltotal]
Wolfram Language code: Dynamic[ProgressIndicator[progress]]
Wolfram Language code: URLSaveAsynchronous[url, FileNameJoin[{$TemporaryDirectory, "10mb.dat"}], progFunction, "Progress" -> True]

Options  (15)

"Method"  (1)

"Method" can be used to specify the HTTP method used by the connection:

Wolfram Language code: tmpFile = FileNameJoin[{$TemporaryDirectory, "tmp.txt"}]; URLSaveAsynchronous["http://wolfram.com", tmpFile, Null, "Method" -> "HEAD"]
Wolfram Language code: FilePrint[tmpFile]

"Parameters"  (1)

Specify the parameters that should be sent to the server:

Wolfram Language code: tmpFile = FileNameJoin[{$TemporaryDirectory, "tmp.txt"}]; URLSaveAsynchronous["http://exampledata.wolfram.com/httpget.php", tmpFile, Null, "Parameters" -> {"name" -> "Joe", "age" -> "30"}]
Wolfram Language code: FilePrint[tmpFile]

"VerifyPeer"  (1)

Verify that the SSL certificate used by the server is valid:

Wolfram Language code: statusData; tmpFile = FileNameJoin[{$TemporaryDirectory, "tmp.txt"}]; eventFunction[_, "statuscode", status_] := statusData = status; URLSaveAsynchronous["https://wolfram.com", tmpFile, eventFunction, "VerifyPeer" -> True]
Wolfram Language code: statusData

"Username"  (1)

Specify the username that should be sent to the server:

Wolfram Language code: tmpFile = FileNameJoin[{$TemporaryDirectory, "tmp.txt"}]; URLSaveAsynchronous["http://exampledata.wolfram.com/authentication.php", tmpFile, Null, "Username" -> "Joe", "Password" -> ""]
Wolfram Language code: FilePrint[tmpFile]

"Password"  (1)

Specify the password that should be sent to the server:

Wolfram Language code: tmpFile = FileNameJoin[{$TemporaryDirectory, "tmp.txt"}]; URLSaveAsynchronous["http://exampledata.wolfram.com/authentication.php", tmpFile, Null, "Username" -> "Joe", "Password" -> "topsecret"]
Wolfram Language code: FilePrint[tmpFile]

"UserAgent"  (1)

Specify the user agent that should be sent to the server:

Wolfram Language code: tmpFile = FileNameJoin[{$TemporaryDirectory, "tmp.txt"}]; URLSaveAsynchronous["http://exampledata.wolfram.com/useragent.php", tmpFile, Null, "UserAgent" -> "Web Browser"]
Wolfram Language code: FilePrint[tmpFile]

"Cookies"  (1)

Manually control the cookies used by URLSaveAsynchronous:

Wolfram Language code: tmpFile = FileNameJoin[{$TemporaryDirectory, "tmp.txt"}]; URLSaveAsynchronous["http://exampledata.wolfram.com/cookies.php", tmpFile, Null, "Cookies" -> {{"Domain" -> ".exampledata.wolfram.com", "Path" -> "/", "Secure" -> "FALSE", "Expires" -> DateString[{2020, 1, 1, 0, 0, 0}], "Name" -> "MyCookie", "Value" -> "CookieData"}}]
Wolfram Language code: FilePrint[tmpFile]

"StoreCookies"  (1)

If False, "StoreCookies" will not place any new cookies found while connecting to the site in the global cookie share:

Wolfram Language code: cookiesData; tmpFile = FileNameJoin[{$TemporaryDirectory, "tmp.txt"}]; eventFunction[_, "cookies", cookies_] := cookiesData = cookies URLSaveAsynchronous["http://wolfram.com/", tmpFile, eventFunction, "StoreCookies" -> False]
Wolfram Language code: cookiesData
Wolfram Language code: $HTTPCookies

"Headers"  (1)

Specify headers to be sent to the server:

Wolfram Language code: tmpFile = FileNameJoin[{$TemporaryDirectory, "tmp.txt"}]; URLSaveAsynchronous["http://exampledata.wolfram.com/headers.php", tmpFile, Null, "Headers" -> {"MyHeader" -> "42"}]
Wolfram Language code: FilePrint[tmpFile]

"BodyData"  (1)

Specify the message body that should be sent when connecting to the server:

Wolfram Language code: tmpFile = FileNameJoin[{$TemporaryDirectory, "tmp.txt"}]; URLSaveAsynchronous["http://exampledata.wolfram.com/bodydata.php", tmpFile, Null, "BodyData" -> "Message body data sent to server."]
Wolfram Language code: FilePrint[tmpFile]

"MultipartData"  (1)

Specify the contents of a multipart message body:

Wolfram Language code: tmpFile = FileNameJoin[{$TemporaryDirectory, "tmp.txt"}]; URLSaveAsynchronous["http://exampledata.wolfram.com/multipartdata.php", tmpFile, Null, "MultipartData" -> {{"partName", "mime/type", {1, 2, 3, 4, 5}}}];
Wolfram Language code: FilePrint[tmpFile]

"ReadTimeout"  (1)

Specify the maximum allotted time in seconds to finish downloading data from the server:

Wolfram Language code: errorString; eventFunction[_, "error", error_] := errorString = error tmpFile = FileNameJoin[{$TemporaryDirectory, "tmp.txt"}]; URLSaveAsynchronous["http://exampledata.wolfram.com/50mb.dat", tmpFile, eventFunction, "ReadTimeout" -> 1];
Wolfram Language code: errorString

"ConnectTimeout"  (1)

Specify the maximum allotted time in seconds to establish a connection to the server:

Wolfram Language code: errorString; eventFunction[_, "error", error_] := errorString = error tmpFile = FileNameJoin[{$TemporaryDirectory, "tmp.txt"}]; URLSaveAsynchronous["http://127.0.0.1", tmpFile, eventFunction, "ConnectTimeout" -> 1];
Wolfram Language code: errorString

"Progress"  (1)

If True, the "progress" event will be raised, returning information downloaded and uploaded about in-progress downloads:

Wolfram Language code: progressData = {};
Wolfram Language code: tmpFile = FileNameJoin[{$TemporaryDirectory, "tmp.txt"}]; progressFunction[_, "progress", progress_] := progressData = progress URLSaveAsynchronous["http://exampledata.wolfram.com/5mb.dat", tmpFile, progressFunction, "Progress" -> True]; Dynamic[progressData]

"UserData"  (1)

"UserData" is any expression containing information to be made available when an event is called:

Wolfram Language code: dataString; tmpFile = FileNameJoin[{$TemporaryDirectory, "tmp.txt"}]; eventFunction[async_, "statuscode", data_] := dataString = "UserData" /. Options[async] URLSaveAsynchronous["http://wolfram.com", tmpFile, eventFunction, "UserData" -> "stored data"];
Wolfram Language code: dataString

Properties & Relations  (1)

Use URLFetchAsynchronous to load the content directly into the Wolfram Language:

Wolfram Language code: constitution; f[_, "data", document_] := constitution = FromCharacterCode[document] URLFetchAsynchronous["http://exampledata.wolfram.com/USConstitution.txt", f];
Wolfram Language code: Short[constitution]
Wolfram Research (2012), URLSaveAsynchronous, Wolfram Language function, https://reference.wolfram.com/language/ref/URLSaveAsynchronous.html.

Text

Wolfram Research (2012), URLSaveAsynchronous, Wolfram Language function, https://reference.wolfram.com/language/ref/URLSaveAsynchronous.html.

CMS

Wolfram Language. 2012. "URLSaveAsynchronous." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/URLSaveAsynchronous.html.

APA

Wolfram Language. (2012). URLSaveAsynchronous. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/URLSaveAsynchronous.html

BibTeX

@misc{reference.wolfram_2026_urlsaveasynchronous, author="Wolfram Research", title="{URLSaveAsynchronous}", year="2012", howpublished="\url{https://reference.wolfram.com/language/ref/URLSaveAsynchronous.html}", note=[Accessed: 13-June-2026]}

BibLaTeX

@online{reference.wolfram_2026_urlsaveasynchronous, organization={Wolfram Research}, title={URLSaveAsynchronous}, year={2012}, url={https://reference.wolfram.com/language/ref/URLSaveAsynchronous.html}, note=[Accessed: 13-June-2026]}