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This member function is called when a CInternetSession object is created.

   LPCTSTR pstrAgent = NULL,
   DWORD_PTR dwContext = 1,
   LPCTSTR pstrProxyName = NULL,
   LPCTSTR pstrProxyBypass = NULL,
   DWORD dwFlags = 0 



A pointer to a string that identifies the name of the application or entity calling the Internet functions (for example, "Microsoft Internet Browser"). If pstrAgent is NULL (the default), the framework calls the global function AfxGetAppName, which returns a null-terminated string containing an application's name. Some protocols use this string to identify your application to the server.


The context identifier for the operation. dwContext identifies the operation's status information returned by CInternetSession::OnStatusCallback. The default is set to 1; however, you can explicitly assign a specific context ID for the operation. The object and any work it does will be associated with that context ID.


The type of access required. The following are valid values, exactly one of which may be supplied:

  • INTERNET_OPEN_TYPE_PRECONFIG   Connect using preconfigured settings in the registry. This access type is set as the default. To connect through a TIS proxy, set dwAccessType to this value; you then set the registry appropriately.

  • INTERNET_OPEN_TYPE_DIRECT   Connect directly to Internet.

  • INTERNET_OPEN_TYPE_PROXY   Connect through a CERN proxy.

For information on connecting with different types of proxies, see Steps in a Typical FTP Client Application.


The name of the preferred CERN proxy if dwAccessType is set as INTERNET_OPEN_TYPE_PROXY. The default is NULL.


A pointer to a string containing an optional list of server addresses. These addresses may be bypassed when using proxy access. If a NULL value is supplied, the bypass list will be read from the registry. This parameter is meaningful only if dwAccessType is set to INTERNET_OPEN_TYPE_PROXY.


Indicates various caching options. The default is set to 0. The possible values include:

  • INTERNET_FLAG_DONT_CACHE   Do not cache the data, either locally or in any gateway servers.

  • INTERNET_FLAG_OFFLINE   Download operations are satisfied through the persistent cache only. If the item does not exist in the cache, an appropriate error code is returned. This flag may be combined with the bitwise OR (|) operator.

CInternetSession is the first Internet function called by an application. It initializes internal data structures and prepares for future calls from the application.

If no Internet connection can be opened, CInternetSession throws an AfxThrowInternetException.

See the example for CFtpFileFind.