Web API requirement.

Question

Hi Folks, 
 
 I'm trying to achieve the following. 
 Use case: 
 In our application, Appian is implementing as a headless application. Business wants to complete tasks from the external web application, but the process flow should be built in Appian. As a poc we are planning to built two screens from the external web application. When the user fills out input parameters and clicks on submit web API will initiate process flow and send back response. 
 
 Now user from the external web application will be on the second screen and fill the input parameters and submit the form this time Appian should able to another 2nd web API and continue the process flow. 
 
 Is it possible to stop process flow till the second API call and then resume process flow whenever we get request from the external system. 
 
 Any inputs would be great, as I'm just beginning, I can implement more efficient code. 
 
 Thanks

Stefan Helzle · Answer

I recently implemented something similar. In the process I had a "Receive Message" event waiting. I had a Web API receiving the data which started a process. This process sends the data via a message to the waiting one. Works, but I think this is not the best solution. Next time I will try to just have short snippets of process, persisting state and data in DB, and each incoming call just figures out by status which process to start next. This way there are no active waiting process instances. Keep an eye on proper validation of incoming data and also if a specific call is allowed in the status the process is in.

legotx · Answer

Why don''t you create two WebAPI endpoints? I think it would be easier and will it it more reusable assuming that you divide the operations properly? 
 For example: 
 Create a Process Model with these Elements 
 
 User Input Task->
 
 Form 1 (Enter User Information) 
 User enters information 
 User submits 
 Send data to Web API #1 
 User gets response.

User gets response -> If continue = YES (XOR Gateway)
 
 YES:
 
 User Input Task 
 Pass data from Form 1 to Form 2 (Enter other details) in Process Variables 
 User enters information 
 User submits 
 Send data to Web API #2 
 User gets response

NO, display reason not to continue

User Input Task -> Form 3 -> Display Confirmation

Web API requirement.

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