After starting a process from third party application by hitting the service of

Ok - to join everything together on this question and expand on the previous one, you'll need to create a process report that runs in the context of the process model that is being started and shows the task ID within that process, then create a Web API that accepts a process ID and uses a!queryProcessAnalytics() to obtain and return the task ID from the aforementioned report.

The documentation you'll need is linked below; you may also want to look at the task report tutorial if you're struggling with a!queryProcessAnalytics().

Process reports: forum.appian.com/.../Process_Reports.html
Web APIs: forum.appian.com/.../Web_API_Tutorial.html
a!queryProcessAnalytics: forum.appian.com/.../System_Functions.html
Task report tutorial: forum.appian.com/.../Task_Report_Tutorial.html

Ok - to join everything together on this question and expand on the previous one, you'll need to create a process report that runs in the context of the process model that is being started and shows the task ID within that process, then create a Web API that accepts a process ID and uses a!queryProcessAnalytics() to obtain and return the task ID from the aforementioned report.

The documentation you'll need is linked below; you may also want to look at the task report tutorial if you're struggling with a!queryProcessAnalytics().

Process reports: forum.appian.com/.../Process_Reports.html
Web APIs: forum.appian.com/.../Web_API_Tutorial.html
a!queryProcessAnalytics: forum.appian.com/.../System_Functions.html
Task report tutorial: forum.appian.com/.../Task_Report_Tutorial.html