This is interesting. We built something very much like this internally at SeatMe. On the iOS side, it's almost identical. It's how we keep our iPads up to date. Might not of built something internally ourselves a year ago if there was a platform like this.

The biggest difference is that since we are not a general platform, we can make assumptions about the model and how version each release and we can built in some constrains and unique security models.

We took a lot of cues from the OData spec and Microsoft's reference design.

The rest of this comment is mostly targeted at the creators of Simperium.

You made very similar design decisions to us in a lot of ways. A lot problems though that you will face I see with your path here so I have a few tips for you.

* It sucks the iOS client isn't open source. I get scared of linking in third party libs into iOS projects because I have to account for anything you do when I go to Apple to submit my app.

* You really got to brush up on the objective-c naming conventions. Not to be harsh but `-(id)getCustomObjectForKey:(NSString * )key;` makes me cringe.

* Don't require me to have to know about your categories.

* Namespace your categories so you don't smash mine ("something like "SP_encodeBase64WithString" instead of "encodeBase64WithString")

* If you include third party libs, you MUST rename them and prefix with your prefix. I see you use ASIHTTPRequest, DDLogger, SocketIoClient, AsyncSocket, Reachability, and a few others. You will smash everyone else's implementations if they already had them included.

* Don't use ASIHTTPRequest internally (it's old and unmaintained and doesn't play nicely with ARC)

* PREFIX ALL YOUR CODE. We don't have any real name-spacing objective-c. As a framework developer, you have to be aware of that more than anyone else. I shouldn't be seeing DiffMatchPatch and SocketIoClient show up in my symbol list after linking your lib

* Your addDelegate/removeDelegate is funny. After you exhausted the need for one delegate, switch to NSNotificationCenter.

* DON'T USE XIB/NIBs. Interface builder for iOS was an after thought and it's only a 90% solution (unlike with Cocoa where interface builder was a first class product built side by side with AppKit). Especially don't make me have to include your XIBs in my bundle. At the very least give me a bundle with it in it.

* Separate your GIT repo. If I want to include your library as a submodule I have to take all the client libraries as well.

Now when it comes to the actual sync layer and how you generate JSON dictionaries and apply "patches" this is fine code.

Here are some feature requests:

* Instead of having to give you a single NSManagedObjectContext let us register them. We have a few (some use different concurrency types).

* Let us override what gets generated or if we want to ignore a field with userInfo keys in the core data model.

* Let us get an idea of your backend sync processes to be able to suspend and start them when we need and know if anything is pending. Give us a callback that you still have things to queued and when we are done so we can at our leisure set up UIBackgroundTasks on iOS 4+.

On an unrelated note, why not create this as a NSIncrementalStore and just put your code behind the persistent store coordinator instead of monitoring it? We are doing the same as you at the high level because we wrote our code pre iOS 5.0 but iOS 5 gives you an awesome new toy there.