For users purchasing services from a website this would be the ideal workflow :
1. (clientside) Select services (via form)
2. (clientside) Browse (not upload here) some needed files (PDF, images)
3. (serverside) Validate form ($_POST)
4. (clientside) Present validation result.
5. (clientside) Edit form in case validation failed (repeat step 3 to 5 as needed)
6. (clientside) Submit form and upload prev. browsed files
7. (clientside) Track upload (AJAX)
As I understood one is not able to cache URL's of local files , so browsing files before (serverside) form validation seems to be quite useless. Browsing files must happen at the end shortly before submitting the form, unless there are options of caching URL's of local files to establish above workflow.
Any hints, any suggestions ?