Crosswalk on Android

Usage scenarios

Crosswalk on Android can support packaging with XDK and Cordova and SysApps.

• XDK
• PhoneGap
• SysApps

Packaging modes

Crosswalk on Android provides a packaging tool and some Java wrapper code which can bundle web applications into Android APKs. Since Crosswalk is a web engine and written in C/C++ and Java code and its size is somewhat big(>16M), here two alternatives are provided to decide whether to include Crosswalk runtime into web applications APKs. Currently two packaging modes are designed for users:

	Embedded mode	Shared mode
General introduction	All are packaged together, including crosswalk runtime and web app. It’s intuitive and preferred by users.	Crosswalk runtime is a web engine with rich features so it’s somewhat big(binary >16M). Shared mode provides one shared binary and a wrapper to call the shared binary. Each web app APK is small because it only includes the resources of web app. Note that the share mode only means sharing crosswalk binary between web apps but not running instances.
Advantages	It's very important that web applications(APKs) have no other dependencies. All are bundled together.	a) It’s small because web app APK doesn’t include the crosswalk runtime, but a thin wrapper. b) Architecture independent. One web app APK for both IA and ARM architectures.
Disadvantages	a) Web app APKs are big >16M even for a small web app. b) Architecture dependent. Each web app has at least two APKs, one is for IA architecture and another is for ARM architecture.	Web app APKs depend on Crosswalk runtime library(XWalkRuntimeLib.apk). Risky when crosswalk runtime library APK is upgraded.
Release targets	xwalk_app_template.tar.gz	XWalkRuntimeLib.apk, xwalk_app_template.tar.gz

Architecture and Components

Web App APK: HTML/JS/CSS + Android manifest, resources + Java wrapper(calling crosswalk runtime)
Runtime library APK: Crosswalk Runtime -> Crosswalk Runtime Core -> Content API -> Blink

Proposal

• The reasons to partition this to several components are:
• Hide the details of its based on components.
• Track each component's quality easily via unit tests and Test shell(APKs used to test the functionalities of the component).
• Provide the whole runtime as a 'library'.
• Isolate them for clear understanding and tracking.
• Web App APK
• APK wrapper by calling runtime Java API
• HTML/JavaScript/CSS files
• Generated from APK template
• Runtime is shared by each web application via library sharing( for the shared mode). Besides, runtime also can be bundled with web app APK( for the embedded mode).
• Runtime
• Runtime Java API, which is simple and easy to use
• API extension infrastructure
• App life cycle, SysApps, Intel API, System Info, UI controls,windowing
• Misc other features
• Generate the runtime as a 'library' APK for Android
• Runtime Core
• An abstraction layer to provide Java classes to runtime and hide the internals of Content and Blink
• Java classes only internally used by Runtime
• Mainly customize and implement Content API by meeting requirements of runtime
• Blink and Content
• Provide HTML5 API, such as WebGL, WebRTC, WebAudio
• Parallel JavaScript, WiDi, etc.
• Performance improvement

BKMs