I have a shape in Visual Overview that should show a thumbnail of a JPG that updates every 5 seconds. The URL stays the same, but the image changes. I'm using 'Link' shape data with the following value:
#http://<DMA IP>/VideoThumbnails/Video.htm?type=Generic Images&source=https://UrlToMyImage.com/myImage.jpg&proxy=false&refresh=5000
I see the image, but it's not refreshing. My source URL is not hard-coded like above, but comes from a parameter value. If I change the URL to something like myImage.jpg?1, it updates once. I think this is cached by the browser.
How can I properly refresh my image without having to update my parameter every 5 seconds, please?
Jochen Dewachter [SLC] [DevOps Advocate] Selected answer as best 27th January 2021
There are a few options:
- When the browser downloads the image, it might also receive http-headers that indicate if (and for how long) the browser is allowed to cache the file. If you have control over the http server that provides the image ("https://UrlToMyImage.com"), then it's possible to configure these http-headers.
- If the DMA agent is able to download the image (has Internet or network access), then it's possible to put "proxy=true" in the url of the VideoThumbnails. When using the proxy, the browser will do an API call to the DMA to get the image, which the browser won't cache.
- If the above options aren't possible, then you'll have to update the source parameter in the url manually, so that the url is different on each refresh interval.
Jochen Dewachter [SLC] [DevOps Advocate] Edited comment 27th January 2021
I’ll go for the proxy=true option. Thanks a lot!