Implement Gzip compression for all requests

[ndegwamartin]

Describe the feature request. We need to enforce GZIP for all requests from the android client. This leads to 7x improvements during sync in terms of bandwidth.

Additional context We have confirmed that currently some endpoints do not use gzip compression when making requests to the backend e.g custom endpoints during initial sync.

Acceptance criteria The app should login and sync down data successfully for all the endpoints/resources.

Area path A list of ordered steps in the app on usage of the feature to support anyone testing it e.g. Code reviewer, QA e.g.

1. Login to the app
2. Sync data

Implementation plan (For Engineers) The plan for implementing the solution e.g. via a description or a check list for the various ordered tasks that will need to be completed.

• On the Android client add the header Accept-Encoding: gzip on all outgoing requests to the server
• On the Gateway investigate why custom endpoint /practitioner-details breaks with Gzip configuration

[pld]

Cool, adding this to current milestone

[ellykits]

Findings

This header is not present in the download requests Accept-Encoding: gzip. The OkHttp client responsible for performing the requests is in the Android FHIR SDK code. FHIRCore HTTP clients will also need to be updated to include this header esp. for the endpoint that returns practitioner-details.

[pld]

nice, this is kinda a great finding, since we should get a speedup from having gzip on, is there an issue on the SDK yet for this?

[ellykits]

No issue yet

[ellykits]

Also, NOTE that the SDK provides a NetworkConfiguration for enabling gzip only for upload requests, defaults to false. We have overridden this in FHIRCore FhirEngineModule enable gzip for the upload requests. The implementation can be adopt for download requests in the SDK.

[pld]

@ellykits based on Aditya's comment on the space gzip is already enabled, https://github.com/square/okhttp/issues/2132#issuecomment-165888326

[Rkareko]

When a breakpoint is added in the OkHttpCall.java class in the parseResponse function that is part of the Retrofit package, and then run rawResponse.networkResponse(), you will see that in the request headers, gzip is set as the encoding method when running fhir core agaimst the stage server https://fhir.labs.smartregister.org/fhir/Patient?organization=144238&_count=100&_sort=_lastUpdated&_summary=count cc @ndegwamartin @ellykits The app is pointing to a non proxy server

[Rkareko]

Apps pointing to the gateway also have the gzip encoding header as seen below

[ellykits]

This issue can be closed. As verified by the screenshots logs shared above by @Rkareko.