React-native-code-push: [UWP] CheckFrequency.ON_APP_RESUME always reports "up to date"

[rozele]

Thanks so much for filing an issue or feature request! Please fill out the following (wherever relevant):

• react-native-code-push version: 0.14.6-beta
• react-native version: 0.34.1
• react-native-windows version: 0.34.0
• iOS/Android version: Windows 10.0.14393
• Does this reproduce on a debug build or release build? Debug
• Does this reproduce on a simulator, or only on a physical device? Desktop
• Repro steps and/or stack trace:
• Run app with codePush.CheckFrequency.ON_APP_RESUME
• Publish update
• Suspend app
• Resume app
• CodePush always reports "App is up to date."
• Restart app
• CodePush downloads update

(The more info the faster we will be able to address it!)

The issue is that the ON_APP_RESUME check frequency does not work as expected and always reports that the app is up to date.

[rozele]

I'm starting to suspect this is some kind of caching behavior built into Windows.Web.Http.HttpClient.

[rozele]

Immediately after an update, the first update check for the given hash usually comes back with a "no update" response. Then all subsequent checks (until app restart) return that same cached response. Just a theory...

[geof90]

Does it still repro if you disable caching in HttpClient in react-native-windows?

[rozele]

Unfortunately it still repros when I set cache-control: no-cache as a header on the HttpRequest object...

[rozele]

But I'm not convinced that's eliminating client-side caching, and I can't find a toggle for such behavior. I could try and add a random parameter (like DateTime) to the URI to see if it still caches...

[rozele]

Okay, so there is more evidence in favor of the client-side caching behavior. By adding a random parameter to the updateCheck URL, the correct response comes back. Now to figure out why HttpClient could be doing this...

[rozele]

Okay, by setting the following on the UWP HttpClient:

``` c#
var filter = new HttpBaseProtocolFilter
{
AllowAutoRedirect = false,
};

        filter.CacheControl.ReadBehavior = HttpCacheReadBehavior.MostRecent;
        filter.CacheControl.WriteBehavior = HttpCacheWriteBehavior.NoCache;

        return new DefaultHttpClient(new HttpClient(filter));

```

Things work properly. Unfortunately, setting Cache-Control: no-cache should have also worked as expected. This is definitely a UWP bug, but I'm also curious if this could be a CodePush bug. EDIT: This is an issue with the Cache-Control header missing from the CodePush service response. Because CodePush can't really know the caching behavior of the underlying HTTP client, shouldn't it send a Cache-Control: no-cache header from the service, or use a URI on the client that changes over time (e.g., by appending a Unix timestamp to the URI to prevent such caching)?

[rozele]

Confirmed that if the service responded with a "Cache-Control" header, then the HttpClient would do the right thing. I'll open another issue on http://github.com/Microsoft/code-push because I don't know where else to file service bugs.

[rozele]

Thanks for the service update @silhouettes, this works flawlessly now!