base starter flow osgi

Base Starter Parent project for Vaadin Flow and OSGi in NPM mode

This project can be used as a starting point to create your own Vaadin Flow application bundle for OSGi. It has the necessary dependencies and files to help you get started. This project has been revised for Vaadin 19 (GA in March 2021) which brings back OSGi support in npm mode. For now, it Vaadin OSGi support is only for Flow based views (Java UIs), but not for Fusion (TypeScript UIs).

For more Vaadin usage samples, you can go to vaadin.com/start.

To access it directly from github, clone the repository and import the project to the IDE of your choice as a Maven project. You need to have Java 8 or 11 installed.

The project consist of two subprojects:

• starter
• app

The starter project contains the code for Web Application Bundle (WAB) which can be deployed to any OSGi container.

The app project contains infrastructure which allows to build an executable JAR file. The resulting application starts OSGi container with all necessary dependencies. It's a fast way to check the WAB inside OSGi environment.

Build and run a Vaadin web application OSGi bundle

The simplest way to start the project is run command mvn install and then run java -jar app/target/app.jar.

The starter project may be built via mvn -pl starter install command. Then mvn -pl app bnd-resolver:resolve command may be used to generate list of bundles required at runtime in OSGi container and the app can be started via mvn -pl app bnd-run:run command.

Deploying Vaadin specific bundles to an OSGi container

Vaadin application generally contains dependencies to other bundles: e.g. Vaadin components like Button, TextField , etc. Every Vaadin component is based on a Web Component which is represented by frontend resources. All frontend resources are built into a bundle along with Vaadin WAB. As a result:

• any Vaadin component bundle update is possible only within the same minor version, so that the Web Component version stays the same (and only Java code is updated). We don't recommend updating any version over a minor for Flow or the web component Flow integrations (even though it's not prevented anyhow at the moment).
• Updating any bundle that has frontend resources requires that the frontend build goal build-frontend is run and the WAB is redeployed to get the static frontend bundle updated.

Limitations

See Limitations section in the starter project README.md.

️ At the moment, it is not possible to modify frontend resources on the fly (webpack dev server is not available at runtime). This means that for every frontend change, you have to rebuild the frontend bundle. (Issue for devmode)