Start Process Using WEB API and get the Response with the Updated Variables

Question

Hi All, 
 I am creating a WEB API which will in turn trigger a process model. 
 Now this is been executed, it contains 2 data store entities which gets updated. 
 now In order to send the response back to the External system My main intention is to send the 
 variables which are updated while executing the process model into the response of the WEB API back, 
 Is this possible, 
 PS: My thought on this is .... this works on asynchronously where it just starts the process. but doesnt care if the process fails or not. 
 Please suggest 
 TIA :) 
 Harsha

rohitr303 · Accepted Answer

Hello Harsha , 
 
Sending the updated process variables as the web api response is possible , You just need to activity chain all the nodes in the process model. And in the web api response body return fv!processInfo.pv.variableName. 
 
Hope this helps. 
 
Thanks, 
Rohit Ouhal

Robert Shankin · Answer

[deleted]

aloks0189 · Answer

Hi harshav420 you shouldn't depend upon the activity chaining to get the updated variables values in web API. 
 
Because, a!startProcess() invokes a process asynchronously which means process might start immediately or with some delay based on scheduling algorithm/ based on load on server by considering load balancing. 
 
I know, when you chain the nodes, Appian tries to complete the execution of the chained node as quickly as possible but you cannot rely on that. As per appian documentation, they have clearly mentioned about startProcess function asynchronous behaviour. 
 
Hence, you cannot be sure about these process to start immediately, it's all your assumptions that it will start immediately, and this will drag your application into issues while it's in production. 
 
Also you can capture few details, whether process started successfully or failed using the following attributes of this function: onSuccess, onError 
 
 I recommend you, not to rely on this approach, because this will be a temporary solution which won't work always. You need to think about some alternate options to achieve your requirement.

aloks0189 · Answer

Hi harshav420 sometime even when you are not performing any complex logic, this might fail due to load on server. Because when we make asynchronous call means we are asking Appian to trigger this process, whenever applicable (based on the resource availability). 
 
So i suggest, do not rely on this, else you will end up with unexpected result/behavior/bugs at any point of time, and you can't even raise a support ticket, because as per the documentation it's the expected behavior, and i have seen several cases where this approach failed even when we perform very light operation.