The ImageTransferMethod property indicates how the chart data is transferred to the source attribute of the <IMG> tag. ImageTransferEnum.Session places the chart data (byte array) into a Session variable, while ImageTransferEnum.Cache places the chart data into a Cache variable. ImageTransferEnum.File writes chart data to a temporary file.
This property only applies to the Manual, HTTPHandler, and ASP Page rendering methods. The following table lists what the effect of an intersection between a transfer method and render method produces:
| Transfer Method | |||
Render Method | None | Session | Cache | File |
Manual | - no tag - no image transfer | - no tag - image transfer in session variables | - no tag - image transfer by application cache | - no tag - image written to file |
HttpHandler | - tag contains reference to the handler specified by the ImageUri property, including parameters - no image transfer | - tag contains session references - image transfer in session variables - auto delete variables - session variables deleted with session termination | - tag contains cache references - image transfer in cache variables - auto delete variables - cache variables expire for cleanup | - tag contains the reference - image transfer by filename - auto delete file |
ASP Page | - tag contains reference to ASP page specified by the ImageUri property, including parameters - no image transfer | - tag contains session references - image transfer in session variables - session variables deleted with session termination | - tag contains cache references - image transfer in cache variables - cache variables expire for cleanup | - n/a – exception thrown |
File | - tag contains reference to file specified by ImageUri. External file cleanup required | - n/a – not used | - n/a – not used | - n/a – not used |
BinaryWrite | - no tag - renders binary stream containing chart image to page response | - n/a – not used | - n/a – not used | - n/a – not used |