Developer Documentation Library > Interviewer - Server > Configuration and customization > Restarting active surveys > Method 2: Multiple parallel instances
 
Method 2: Multiple parallel instances
This method also allows the respondent to restart from the ACTIVE queue. It works for interviews that are restarted on different engines than originally used.
This feature relies on the transfer of cache files in order to ensure data remains consistent. This means that if a respondent uses multiple browsers to take the survey, the case data might be inconsistent for a brief period. Generally the data is made consistent when the transfer process runs, but in some situations the correct data cannot be determined.
To enable this feature
1 Use DPM Explorer to create a site-wide DPM property called TrackWebSessions under Site > Properties. Set its value to 1.
The TrackWebSessions property can also be set on a per project basis in DPM in Site > Servers > Projects > [ProjectName] > mrInterview.
2 Update the sample management script by setting the RESTART_FROM_ACTIVE value to True.
More information
TrackWebSessions
(DPM property.) Controls whether the interview session token is tracked in the DataCollection.InterviewerID system variable. This property prevents multiple sessions from being started concurrently against the same respondent ID.
1: The interview sessions token is written to DataCollection.InterviewerID.
0: The interview sessions token is not written to DataCollection.InterviewerID.
DataCollection.InterviewerID
(System variable.) The interviewer ID. This property is not supplied for projects using inbound sample management (the variable is then set to ""), unless TrackWebSessions is set to 1. When TrackWebSessions is set to 1, the interview session token is stored for the interviewer ID.
See also
Method 1: Connect back to original instance of interview
Restarting active surveys