Support for downloading only diffs between CodePush updates?

[yugun-ilevit-com]

Hello @floydkim,

In the original code-push-server setup, it was possible to serve diff packages so that clients would only download the delta between two CodePush updates, rather than always fetching the full bundle. This was very helpful to reduce data transfer costs (especially when using a CDN like CloudFront) and speed up updates for users.

With @bravemobile/react-native-code-push, I’d like to ask:

1. Is it also possible to download only the diffs between CodePush versions with this package?
2. If yes, could you point me to the relevant part of the code (client logic and/or server-side requirements) that enables diff downloads?
3. If no, are there plans or recommended approaches to add/enable this feature?

Thanks in advance for clarifying!

[yugun-ilevit-com]

4. If not, is there a recommended strategy (for example, what Soomgo internally uses) to reduce CloudFront data transfer costs when always serving full bundles?

[floydkim]

Hi, @yugun-ilevit-com

There is currently no feature to transfer only the diff between updates.
As you may already know, to achieve the behavior, you would need to set up a server using the microsoft/code-push-server project.

I think..
The JS bundle transferred during updates is a single bytecode file, so it will always be sent in full.
Therefore, the larger the assets outside of the JS bundle, the greater the potential benefit of delta updates.
However, larger asset sizes also mean a heavier burden on the first CodePush update.
We try to avoid this situation altogether.
We only allow small-sized resources, and everything else is served remotely.

Depending on the purpose or domain of the app, this may vary, but in our case, we always send updates around 7MB.
Since our service is limited to Korea, this size is not a problem considering the network infrastructure.
According to Firebase Performance Monitor measurements, 90% of users receive the update within 3 seconds (with a median under 1 second).

But, reducing update size is still important.
Although we don't have concrete plans yet, it seems feasible to support incremental updates using bsdiff. (reference)
Or if module federation becomes reliably supported in Metro, we might even consider a complete shift in approach. (reference)