+///\r
+/// HTTP_IO_CALLBACK_EVENT\r
+///\r
+typedef enum {\r
+ HttpIoRequest,\r
+ HttpIoResponse\r
+} HTTP_IO_CALLBACK_EVENT;\r
+\r
+/**\r
+ HttpIo Callback function which will be invoked when specified HTTP_IO_CALLBACK_EVENT happened.\r
+\r
+ @param[in] EventType Indicate the Event type that occurs in the current callback.\r
+ @param[in] Message HTTP message which will be send to, or just received from HTTP server.\r
+ @param[in] Context The Callback Context pointer.\r
+\r
+ @retval EFI_SUCCESS Tells the HttpIo to continue the HTTP process.\r
+ @retval Others Tells the HttpIo to abort the current HTTP process.\r
+**/\r
+typedef\r
+EFI_STATUS\r
+(EFIAPI * HTTP_IO_CALLBACK) (\r
+ IN HTTP_IO_CALLBACK_EVENT EventType,\r
+ IN EFI_HTTP_MESSAGE *Message,\r
+ IN VOID *Context\r
+ );\r
+\r