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 Java wrapper layer which can bundle web applications into Android web app APKs. The Java wrapper layer can call Crosswalk runtime. Since Crosswalk runtime is a full-featured web engine mostly written in C/C++ and its size is somewhat big(> 16M), here two alternatives are provided to decide whether to bundle Crosswalk runtime with web apps. Currently two packaging modes are designed for users:

	Embedded mode	Shared mode
General introduction	All are packaged together, including crosswalk runtime, Java wrapper and a web application into one web app APK. It’s intuitive and preferred for many usage scenarios.	The shared mode provides one shared standalone APK(called Crosswalk runtime library APK). The web app APK only pack web app and the Java wrapper layer which calls the shared binary included in the Crosswalk runtime library APK. So one web app APK is small.
Advantages	It's very important that web app APKs have no other dependencies. All needed are bundled together.	a) It’s small because web app APKs don't pack the crosswalk runtime, but a thin Java wrapper layer. b) Architecture independent. One web app APK can work 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 needs at least two APKs, one is for IA architecture and another is for ARM architecture.	Web app APKs depend on a Crosswalk runtime library APK(XWalkRuntimeLib.apk).
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
• Java 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