Bridget for Android

Thrift definitions of the API for communication between the Android native app and apps-rendered webview content

Introduction

Bridget is our system for communication between TypeScript running in a WebView and the Android (or iOS) native code. Bridget uses Thrift to define the functions the WebView expects the native layer to provide and to define the types of the parameters the WebView must use when calling those functions. This avoids ad-hoc, untyped communication methods, e.g. special URLs or JavaScript interfaces, which are error prone.

Module structure

• Directory src/main/thrift contains Thrift definitions of types and services.
• Package com.theguardian.bridget.thrift contains Java classes generated from those definitions.

Generated classes

The classes in com.theguardian.bridget.thrift are generated using this command:

thrift -out library/src/main/java/ -gen java:generated_annotations=undated library/src/main/thrift/native.thrift

These classes are automatically generated using a Github Action whenever Bridget is updated. A jar with the updated classes is then added to the android-news-app repo in a pull request. See the readme there for how to merge the PR.

Manually updating Bridget version

1. Get the latest native.thrift and copy it to this project: https://github.com/guardian/bridget/blob/main/thrift/native.thrift -> https://github.com/guardian/bridget-android/blob/main/library/src/main/thrift/native.thrift

2. Add back the namespace header to thrift file namespace java com.theguardian.bridget.thrift

3. Append the Bridget version at bottom of the thrift file, e.g const string BRIDGET_VERSION = "2.0.0"

4. Run the thrift command:

   thrift -out library/src/main/java/ -gen java:generated_annotations=undated library/src/main/thrift/native.thrift

   • Note: This will require you to install the thrift compiler. Homebrew can install the latest version with brew install thrift

5. Generate a jar file by running the command at root of the project

   ./gradlew :library:build

   • The generated jar will be located at /library/build/libs/library.jar

6. Copy the generated jar to the Android news app repo:

   mv -f library/build/libs/library.jar ../android-news-app/bridget/src/main/libs/bridget.jar

7. Commit and create a PR