Low-level URL Manager Functions

The low-level URL Access Manager function, URLOpen , allows you to asynchronously download data from or upload data to a URL. The URLOpen function gives you more control over the data transfer than provided by the synchronous URL Access Manager functions.

For download operations, if you do not specify a file in which to store the data, you repeatedly call URLGetBuffer which retrieves the next buffer of data from the URL Access Manager's buffers so that you can manipulate the data or write it to the destination of your choice. When you call URLOpen in this way, you can define an event notification routine and the events for which you want to receive notification. The URL Access Manager includes definitions for URL-specific events, such as when data becomes available for downloading, when a transfer is complete, and when a certain percentage of data has been transferred.

When you call URLOpen , you can specify whether existing files are to be replaced, whether to encode or decode files in BinHex format, whether to display an authentication dialog box if the URL requires authentication, and whether to display a progress indicator.