Two way Integration with ServiceNow

ServiceNow -->Appian --->ServiceNow
We have a scenario where From ServiceNow user will request an action and then will redirect to Appian, In appian we have around 20 interfaces developed, based on the action requested they will redirect to one particular interface among the 20 interfaces. After performing evidence collection again after submit and toggle back option they need to redirect back to requested action page in ServiceNow. 
How to implement this functionality? What are the prerequisites needed and what are the limitations ? 

Help is much appreciated.