WinInet Functions

WinInet functions and structures are defined in the WinInet.h header file. HTTP and FTP use several of the same WinInet functions to handle data. These common functions handle tasks consistently, regardless of the protocol they are applied to.

These common WinInet functions can be used to create general-purpose functions that handle tasks for FTP and HTTP. For example, these functions can perform the following HTTP and FTP tasks:

Downloading files from another computer over the Internet can be handled by the InternetReadFile, InternetFindNextFile, and InternetQueryDataAvailable functions.
Viewing and changing options are handled by the InternetSetOption and InternetQueryOption functions.
- InternetSetOption accepts an unsigned long integer value that indicates the option to set, a buffer to hold the option setting, and the buffer length.
- InternetQueryOption accepts an unsigned long integer value that indicates the option to query, a buffer to hold the option setting, and a pointer that contains the variable address containing the buffer length.
The InternetCloseHandle function closes all HINTERNET handles. For more information about Internet handles, see HINTERNET Handles.

For applications that download multiple files or handle multiple tasks, waiting for each task to complete before moving on to the next task can be extremely inefficient. To avoid waiting, many of the Internet functions provide a way to perform tasks asynchronously. For information on using the Internet functions asynchronously, see the Microsoft Developer Network Web site at http://msdn.microsoft.com/developer/.

The following table shows WinInet functions supported by Windows CE.

Function	Description
InternetCanonicalizeUrl	Converts a Uniform Resource Locator (URL) to a canonical form, including conversion of unsafe characters into escape sequences.
InternetCloseHandle	Closes a single Internet handle or a subtree of Internet handles.
InternetCombineUrl	Combines a base and relative URL into a single canonicalized URL.
InternetConnect	Opens an FTP or HTTP session for a specified site.
InternetCrackUrl	Parses a URL into its component parts.
InternetCreateUrl	Creates a URL from its component parts.
InternetErrorDlg	Displays a dialog box for the error passed to the InternetErrorDlg function.
InternetFindNextFile	Continues a file search from a previous call to the FtpFindFirstFile function.
InternetGetCookie	Retrieves the cookie for the specified URL.
InternetGetLastResponseInfo	Retrieves the last Windows CE Internet function error description or server response on the thread calling this function.
InternetLockRequestFile	Enables the user to place a lock on the file being used.
InternetOpen	Initializes Windows CE Internet functions.
InternetOpenUrl	Begins reading a complete FTP or HTTP URL. For a relative URL and a base URL separated by blank spaces, InternetCanonicalizeUrl must be called first.
InternetQueryDataAvailable	Queries for the amount of data available.
InternetQueryOption	Queries for an Internet option on the specified handle
InternetReadFile	Reads data from a handle opened by the FtpOpenFile, FtpFindFirstFile, or HttpOpenRequest functions.
InternetReadFileEx	Reads data from a handle opened by the InternetOpenUrl, FtpOpenFile, GopherOpenFile, or HttpOpenRequest functions.
InternetSetCookie	Creates a cookie associated with the specified URL.
InternetSetFilePointer	Sets a file position for the InternetReadFile function.
InternetSetOption	Sets an Internet option.
InternetSetStatusCallback	Sets up a callback function that Windows CE Internet functions can use during an operation.
InternetTimeFromSystemTime	Formats the time and date.
InternetTimeToSystemTime	Converts a HTTP time and date string to a SYSTEMTIME structure.
InternetUnlockRequestFile	Unlocks a file that was locked using InternetLockRequestFile.
InternetWriteFile	Writes data to an open Internet file.

WinInet Functions

Function

Description