we starting our process from REST API. Is there any automatic way, to check that all needed variables for the process are set? And if there are not all required variables set, I would receive Response code 400 and process would not be started?
You can make a REST call to <code>/service/form/form-data?processDefinitionId=value</code> and it will return the formProperties in JSON response. For each of the form properties, you can check if the required attribute is true or false.