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Comment by yonkshi | Hacker News Reader

Having recently built an offline first app (mobile app I'll admit), we didn't use a command queue, and I regret it deeply now. I advise everyone who's reading this to go for a command queue. Saves a lot of time debugging data sync.

Our biggest challenge was to sync data with relationships, especially data with circular relationships. We couldn't come up with a generic way to sync circular relationships, so we ended up building a very special purpose buffer on both client and server side.

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What was the challenge with circular relationships? I work on an offline-first system and all inter-object relationships are managed by GUIDs, so cyclical references don't present any problems - objects are sent and received as one big list keyed by guids, not as a tree.

"objects are sent and received as one big list keyed by guids, not as a tree"

That's an interesting pattern I've not heard of before - any links you could recommend for more details on it? It sounds really useful for moderate sized data sets.

I remember coming across it fairly heavily in react/redux stuff, mostly because it makes dealing with redux's stores a lot simpler if you avoid nested structures like that.

There's a library called normalizr[1], whose purpose is to take nested API responses and turn them into flat structures. Have an article[2] about it.

[1]: https://github.com/paularmstrong/normalizr

[2]: https://tonyhb.gitbooks.io/redux-without-profanity/content/n...

didn't Netflix do a bunch of research into json-graph? They seemed to have figured this problem out.

Did you consider using an off-the-shelf solution like Realm?

In my experience it made it trivial to handle the synchronization of arbitrarily complex object graphs (including those with circular dependencies).

is there anything more you can say about your buffer solution? Curious if it is something similar to vector clock syncing that you guys came up with.

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