Syncing again Mac, iPhone, iPad

Hi, i’ve struggled on and off for a while with the sync across devices when using iCloud or Cloudant, but the best solution that seems to work well is to setup a CloudDB on my Mac and have TapForm devices sync with that. So far no lost data.

I ran CouchDB on my Mac for the longest time, I eventually shifted it to a Linux box that I do some other database work on. I’ve not had issues with sync, even with attachment heavy documents, for a long time. I have a 32GB document and 11GB that I sync fine via CouchDB to multiple devices. My biggest problem is sometimes my CouchDB server is offline and the sync system complains at me that it’s unavailable.

John, ya there’s some post installation setup stuff that you could do, but some of it is optional and not necessary if you’re running CouchDB on your own local network.

If you’re dealing with iCloud then you’ve got to wait for it’s request throttling limitations as well as bandwidth/latency constraints on your own connection which means you’ll have to leave Tap Forms active in the foreground so that it can complete a sync. It’s the same for other platforms like CouchDB and Cloudant as well. Even on my local network using CouchDB it can take a minute or two for my iPad to fully sync when I’ve made significant changes.

I used to use the iCloud sync on Tap Forms 3 and remember leaving my iPad on power for hours during sync at times to get everything up to date. iCloud is slow and when you can’t cheat by having fully background processes like Apple does, there isn’t any good workarounds for applications beyond keeping them open for a while.

And I again add my name to this list of disaffected sync-ers. None of three suggested mechanisms (iCloud, Cloudant, or Nearby) work for me – either sync doesn’t happen or it is incomplete or wipes out records on one of my 4 devices (2 iPads, an iPhone, and a MacBook Pro). Brendan, you told me a few months ago in a private email exchange that sync was the bane of your existence. Until you get it fixed reliably (Cloudant was good before IBM took it over and it became incredibly complex to setup), I can no longer use your software even tho I have been a user ever since Bento disappeared.

Bento only ever supported syncing from a Mac to an iPad and it was manual sync as well. Though you’re going between two devices and you’re cognisant of having to do the sync otherwise your changes didn’t get to the other side. You had to be aware of it and explicitly do it though perhaps for some folk that would make it more explicit if the same behaviour occurred with Tap Forms.

Multi master sync is hard, especially when you factor in sync failures, devices that might be offline frequently and conflicting edits. My understanding is that Tap Forms automatically resolves the conflicts based on the last record edited. However that can still inadvertently lead to data loss if you edit a record on a device, realise that it’s out of sync and then trigger the sync you will loose data. Last write wins is a common resolution strategy. An alternative would be having to manually reconcile every change and perhaps that’s an improvement but that could in some situations lead to hundreds or thousands of records being out of sync (an updated calculation or script could easily trigger changes to records).

iCloud Sync seems consistently problematic which in part makes sense because it’s backed by Apple’s notoriously finicky platform. Even Apple’s own apps mess up iCloud so I’m not surprised that Tap Forms has some challenges with the platform too. I am more curious about the Nearby Sync and Cloudant failures though.

For Nearby Sync I found quirks at times when everything talked to everyone because you’re basically inviting a race condition to occur. I did have some weirdness at times in propagation that generally got solved by moving it to a star topology where Tap Forms on my iMac had every other device added to it and then every other device only had the iMac. Nearby Sync works on a pull basis when the app is open and only when you’re on the same network, so it is actually easy to open up the app, make changes and realise that your device is out of sync. Nearby Sync I think is great if your devices are at a single location and you can have one instance of Tap Forms (I use a Mac but you could use any device that runs Tap Forms) open consistently for everything to sync against. If you have multiple devices and they aren’t always running Tap Forms when the changes are made then you will end up with situations where devices don’t have all of the changes because Tap Forms needs to be on at the same time on those devices for nearby sync to work.

The Cloudant/CouchDB side should make that better because it’s a hosted server model. Instead of having one Tap Forms app open all of the time, there is a server that is always on. That said if you lose connectivity to that server, you can’t push the changes but offline editing will still happen. There are a few situations where I believe Tap Forms will pause sync indefinitely depending on the error it receives (e.g. unable to connect to the server), that could trip someone up who is expecting it to be working but not realising it hasn’t been. This is generally easy to triage: on the Mac if you look at the bottom right after you make a change the “last uploaded” time should update and if you make a change on another device last downloaded should change; those same timestamps exist on iOS on the Tools tab.

Hopefully that helps folk out and make sync a little more reliable.