I am writing a set of VBA macros in which it uses the XMLHTTP object to send asynchronous requests to a server. I am sending Basic Authentication with:
XMLH
These questions have been discussed in many ways due to major browsers different implementations of caching methods.
I will give you what worked for me and then the sources I found on this feature.
The only solution I could came across was to force the browser to not cache the request.
myURL = "http://my.domain.com/myscript.cgi"
Dim oHttp As New MSXML2.XMLHTTP
oHttp.Open "POST", myURL, False
oHttp.setRequestHeader "Content-Type", "application/x-www-form-urlencoded'"
oHttp.setRequestHeader("Cache-Control", "no-cache");
oHttp.setRequestHeader("Pragma", "no-cache");
oHttp.setRequestHeader("If-Modified-Since", "Sat, 1 Jan 2000 00:00:00 GMT");
oHttp.setRequestHeader "Authorization","Basic " & Base64EncodedUsernamePassword
oHttp.send "PostArg1=PostArg1Value"
Result = oHttp.responseText
It seems that Cache-Control
works on most browsers and Pragma
only on Firefox and not IE (don't know why...)
If-Modified-Since
is used for IE, since IE uses different settings in his own algorithm to determine whether or not the request should be cached. XMLHttpRequest seem to not be treated as the same as HTTP responses.
Careful : With this code you will need username
and password
each time a new object is created. Maybe you should create a new object, instantiate it once and then destroy it after use. In between you would have all your requests handled in different functions with only one authentication.
MSDN setRequestHeader Method
MSDN IXMLHTTPRequest
XMLHTTPREQUEST CACHING TESTS
XMLHttpRequest and Caching