Appian Community and Appian Academy are being upgraded. As a part of the upgrade, Appian Community is currently in read-only mode, and user registration is disabled until August 3. We apologize for any inconvenience this may cause, but a more secure, stable, and performant Community experience is coming soon!
The new Appian Community launches August 3, followed by Appian Academy on August 7. During the migration, Appian Community Edition, Appian Academy, Documentation, Certifications, Instructor-led Customer Training, Partner Sales Training & Accreditation, and Forum (for Appian Partners and Customers only) will remain available.
I have one web api which is using a!startProcess to call the process async. As it is async and does not wait for process model to complete it is not updating the process variables in the response.
What are the possible fixes we can do?
Discussion posts and replies are publicly visible
Hi agam and Stewart Burchell I have activity chaining but we have loop there. I will explain the scenario in detail, consider we are creating 5 different cases in appian application sent from the external system. There is one process variable of type array which has 5 cases to create and for each one a loop will run inside the process we called from the API. In the response I need all the 5 case ids to be returned but it is returning 2 of them as nulls.
It would not have returned any of the case ids if activity chaining was not there.I suppose it is happening because process runs async and as we have loop the process variable is updated but before the 4th 5th iteration completes it returned the response.
"cases" : [ {"caseId" : 375,"status" : "CREATED"}, {"caseId" : 376,"status" : "CREATED"}, {"caseId" : 377,"status" : "CREATED"}, {"caseId" : null,"status" : "CREATED"}, {"caseId" : null,"status" : "CREATED"}, {"caseId" : null,"status" : "CREATED"} ]
What is your loop doing? Could you create 5 CaseIds in an Expression Rule (called from a single Script Task node)?
No for each case we need to start a sync sub process which in turn creates the case and creates the history of the case and then returns the case id back to the parent process model.
But can you not generate the CaseIds up front, and then pass one each to each of the instances of the sub-process which would then create the Case with that CaseId? That is front-load the generation of the CaseIds...
You mean I check the last case id created in database and then based on the number of cases I have in API request to create I assign those case ids by incrementing the last case id and then call the sub process for each of the case assuming it will also create the same case ids as auto generated values from the db?
Kind of. Separate the generation of the CaseIds from the creation of the Cases themselves. I presume you're generating some human friendly readable CaseId. Create the number that you need (you could use a Stored Procedure to do this to ensure that any concurrent API requests don't overlap), return them to the Process and hand them out to the sub process instances as required to use.
Hi radhikam0005,
If your response is returned like this and in the process the case id's are present as expected, then you are running out of activity chained nodes. At any time, max of 50 chained nodes can be executed and then activity chaining would by default break but the process would continue.
You can read it over here: https://docs.appian.com/suite/help/20.1/Process_Model_Recipes.html#breaking-a-chain
You can follow the approach Stewart has suggested below, I would prefer that as well.
If you want to not use stored procedure, save blank rows in your database to generate new id's in your table and then update the ID accordingly in your loop to map the ID's.
if your case creation scenario is more complicated and creating ID's upfront doesn't look feasible I would suggest to restrict one case creation at once or remove looping and create a logic which allows writing multiple rows at once.
agam Stewart Burchell You guys are correct activity chaining is passing 50 nodes. I will consider redesigning the process model in such a way that I get all the case ids at once instead of getting them one by one out of the loop. Thank you for suggesting the solution.
Can you little bit elaborate about the stored procedure? What it should be doing?
radhikam0005 The idea is to get case id's generated at once. You can do that by writing INSERT statements on your table through a stored procedure. The same can be done via write to data store where you could initially write blank rows to get case id's (I assume you are creating them using auto increment primary ID of your table)
Once you get the generated Id's (either via stored procedure / process), you can use them to map it in your loop to individual case and populate the remaining details in your table.