open method

Article
01/27/2012

[This documentation is preliminary and is subject to change.]

Assigns method, destination URL, and other optional attributes of a pending request.

Syntax

HRESULT retVal = object.open(bstrMethod, bstrUrl, varAsync, varUser, varPassword);

Standards information

XMLHttpRequest, Section 3.6.1

Parameters

bstrMethod [in]
Type: BSTR

BSTR that specifies the HTTP method used to open the connection: such as GET, POST, or HEAD. This parameter is not case-sensitive.
bstrUrl [in]
Type: BSTR

BSTR that specifies either the absolute or a relative URL of the XML data or server-side Web services.
varAsync [in, optional]
Type: VARIANT

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 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, send operations are synchronous, and Internet Explorer does not accept input or produce output while 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 send operation to complete.

**Performance Note: ** When varAsync is set to VARIANT_FALSE, send operations are synchronous. Input is not accepted, nor output produced, while 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 send operation to complete.
varUser [in, optional]
Type: VARIANT

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.
varPassword [in, optional]
Type: VARIANT

VARIANT that specifies the password for authentication. This parameter is ignored if the user parameter is NULL ("") or missing.

Return value

Type: HRESULT

If this method succeeds, it returns S_OK. Otherwise, it returns an HRESULT error code.

Remarks

open was introduced in Windows 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 Warning: ** 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 send to send the request and data, if any, to the server.