In Map Activities to Forms, there are two ways of mapping an activity. Mapping to External Form is the second way. This feature allows one to map a process's activity to a page hosted externally outside of Joget.
When an assignment is opened by the assignee from the Inbox, instead of viewing the usual Joget form, a iFrame will be shown pointing to the External Form defined in the activity mappings. A number of useful information about the assignment will be passed over as request parameter when the iFrame is loaded.
Parameters that will be passed into external form from Joget:
Figure 1: Inbox showing assignment that is mapped to External Form
It is important to note that from this point onward, Joget will no longer has control over the content of the form nor in control of the workflow process anymore. The external page must now handle the form retrieval / validation / saving by itself.
One will then need to invoke the necessary API offered by Joget to complete the assignment in order to move on to the next node in the workflow process. See JSON API Integration | Complete the Assignment with Variables