Hello License Developer,
This scenario is achievable with Sitefinity. Namely, just like anything else in Sitefinity Images & Documents module has fully exposed API. You can find the walkthrough here:
So, what you will need to do is implement the UI on the public side and simply use our API. Since every item in the Images & Documents module (image, pdf, text document, video...) is actually an IContent object, and since Images & Documents module is based on Generic Content module, you will also be able to reuse the workflow rather painlessly. Here is a bit more info on Generic Content based modules:
Unfortunately, there is no sample on how to enable the workflow, but it should be included in the manual by the end of this month.
I hope you'll find this information helpful. Let us know if there is anything else we can do for you.
All the best,
the Telerik team
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