July 29, 2018 update: These issues have been resolved.
Original text: Troy, who is creating a large app for the sales team at his company, reported getting intermittent error messages when editing apps. While the issue appears to mostly have disappeared, we think that the size of his app could be an issue.
Here’s what our technical founder David replied:
Hi Troy,
The issue you have been experiencing can certainly be due to an issue with your network, but it’s more probable that the size of your app makes it difficult for our server to keep up. This following is pretty detailed, so feel free to skip ahead if you’re not interested in the inner workings of Calcapp.
The error you’ve been seeing
Changes you make to your app are synchronized with our server once every five seconds. Validating the changes (checking if they’re acceptable) takes our server 5 to 8 seconds for your particular large-ish app.
Changes are always valid if there is nothing wrong with Calcapp Creator. The validation step on the server is there to make sure that bugs in Calcapp Creator never risk making your app uneditable. If the server detects that anything is amiss, you get a message to that effect and you’re then able to reload Calcapp Creator and continue editing the app. If it hadn’t been for the validation step on the server, it would be probable that bugs in Calcapp Creator could cause your app to become corrupted and uneditable. We do fix bugs in Calcapp Creator when we get (automated) reports, but there will always be bugs we haven’t discovered yet and the last thing we want is for your apps to stop working.
Currently, the validation step goes over your entire app and makes sure that the changes don’t introduce any errors. The project we have in the works would simply only look at the changes, significantly speeding up the process and putting an end to the effective app size limit we appear to have today. This was actually an issue with running apps before – we recently made changes that ensure that even very large apps now load very quickly. The only remaining issue with large apps is editing them.
If this continues to be a problem for you, there’s a band-aid we can apply. We could detect that you’re editing a large app and synchronize changes once every ten seconds (or even once every fifteen seconds), so that our server can keep up. This will negatively impact the user experience, though, as formulas are checked by the server. That means that formula errors wouldn’t be reported as quickly.
Using two computers to edit apps simultaneously
I just re-read your message, and if you use two different laptops to edit apps at the same time you should be getting an error message. That’s by design. It shouldn’t say that “our server isn’t responding,” though, it should say that “your data has changed since you last retrieved it, possibly in a different web browser window or on a different computer.”
You can’t use two computers at once to edit an app because then the two computers will have a different idea of what the app looks like. The server detects this issue and makes Calcapp Creator display an error message.
Email subject lines
You’re in luck, this feature was added just this month! Subject lines can be set to unchanging values, but also through formulas, so this should fully satisfy your request!