I have a feature where the user clicks a link to run a process in the background and perform some actions. What I want to do is to display a message to the user while the PM is running so they know that something is going on. However, I found out that you can't do any other saves until the onSuccess is run. I want to run the following code.
a!dynamicLink( showWhen: not(ri!inProgress), value: true, saveInto: { a!save(ri!showMessage, true), a!startProcess( processModel: cons!WM_PM_SYNC_HOLDS_DATA, processParameters: { siteAcronym: ri!siteAcronym, siteId: ri!siteId, writeType: ri!writeType, user: loggedInUser(), lastSyncDate: ri!lastSyncDate }, onSuccess: { a!save( ri!processInstance, fv!processInfo.pp.id ) }, onError: a!save(ri!error, "error") ), } ),
In the code above, a!save(ri!showMessage, true) is not executed until the onSuccess() in the starProcess() is run even though it's outside of the startProcess. I've tried chaining the process and without any chaining and that save always waits for the PM on success or onError(). Is there a way to get around this? I know there is other ways like using a process report which is what I'm doing, I just want to know if this scenario is possible.
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One possible way might be to have the PM write a "I'm now running" value to a DB table, and have your interface have a refreshVariable (set to auto-refresh every 30s say) that is fetching that value from the DB, and then an interface widget that displays the appropriate message. When the process ends it can then change the value in the DB to a "I'm done" value, the refreshVariable will then eventually fetch that value and your interface widget can now display a different message.
This is a good example of why the timer-based auto refresh should have much lower options than the current minimum of 30 seconds. This sort of example would be best served by a 5 second refresh interval, for example. A relatively trim query would have basically no negative impact on system performance by being run every 5 seconds.
Totally agree and this is the reason why I asked this question. We are using a refresh variable to pull from the process report. Unfortunately there is that instance when the user can run the process at the right as to make them wait an extra 30 seconds causing an unnecessary delay even though things have completed. It would be nice to have this updated on a future release
Another case we tried was to have the 30 second refresh, but have that local variable also refresh on another variable change. So we chained the process model and updated a variable inside the onSuccess() to trigger the local variable refresh but that didn't quite behave as expected. Even after the onSuccess() was done and the reference variable changed, sometimes the timer would still take over and force it to wait longer.
Instinctively I'd want to flip the model and have the Server send the relevant event to the waiting client rather than client "polling" the server. I see there's something called SSE (https://ably.com/topic/server-sent-events) so will do some digging to see if this is on the radar/road-map.
This sound like a good idea. I think this would be the way. Instead of the client trying to guess when something happens, let the server inform the client when that something has happened.
Jose H. said:So we chained the process model and updated a variable inside the onSuccess() to trigger the local variable refresh but that didn't quite behave as expected.
The issue here lies in Appian's behind-the-scenes variable value-setting execution (just based on what I've been able to observe from external evidence). Sometimes chainings of updates like this fail to work how we expected, in seemingly unintuitive ways, because while we assume Appian will do everything in order, it really attempts to execute everything (or at least many of the things) all at once.