Assigns method, destination URL, and other optional attributes of a pending request.
HRESULT open( BSTR bstrMethod, BSTR bstrUrl, VARIANT varAsync, VARIANT varUser, VARIANT varPassword );
- [in] BSTR that specifies the HTTP method used to open the connection: such as GET, POST, or HEAD. This parameter is not case-sensitive.
- [in] BSTR that specifies either the absolute or a relative URL of the XML data or server-side XML Web services.
- [in] VARIANT that specifies VARIANT_TRUE for asynchronous operation (the call returns immediately), or VARIANT_FALSE for synchronous operation. If VARIANT_TRUE, assign a callback handler to the IHTMLXMLHttpRequest::onreadystatechange property to determine when the call has completed. If not specified, the default is VARIANT_TRUE.Performance Note When varAsync is set to VARIANT_FALSE, IHTMLXMLHttpRequest::send operations are synchronous, and Windows Internet Explorer does not accept input or produce output while IHTMLXMLHttpRequest::send operations are in progress. Therefore, this setting should not be used in situations where it is possible for a user to be waiting on the IHTMLXMLHttpRequest::send operation to complete.
- [in] VARIANT that specifies the name of the user for authentication. If this parameter is NULL ("") or missing and the site requires authentication, the component displays a logon window.
- [in] VARIANT that specifies the password for authentication. This parameter is ignored if the user parameter is NULL ("") or missing.
Returns S_OK if successful, or an error value otherwise.
IHTMLXMLHttpRequest::open was introduced in Internet Explorer 7.
The following HTTP verbs and World Wide Web Distributed Authoring and Versioning (WebDAV) methods are supported:
Verb / Method Defined In HTTP (RFC-2616) Defined In WebDAV (RFC-2518) Function GET HTTP WebDAV Request URI POST HTTP WebDAV Send data to server HEAD HTTP WebDAV Request URI without body PUT HTTP WebDAV Store data for URI DELETE HTTP WebDAV Delete data for URI MOVE WebDAV Move URI to to new location PROPFIND WebDAV Request URI Properties PROPPATCH WebDAV Update or Delete URI Properties MKCOL WebDAV Create collection at URI COPY WebDAV Create copy of URI LOCK WebDAV Create Lock UNLOCK WebDAV Remove Lock OPTIONS HTTP WebDAV Request URI Options
Internet Explorer caches the results of HTTP GET requests in the Temporary Internet Files (TIF) folder. In most cases, caching improves performance for data that will not change frequently. To guarantee that the results are not cached, use POST.Security Alert Cross-domain, cross-port, and mixed protocol requests are not allowed. The bstrUrl parameter may only specify files in the same domain, using the same port and protocol method, as that from which the page is served.
Although this method accepts credentials passed via parameter, those credentials are not automatically sent to the server on the first request. The varUser and varPassword parameters are not transmitted unless the server challenges the client for credentials with a 401 - Access Denied response.
After calling this method, use IHTMLXMLHttpRequest::send to send the request and data, if any, to the server.