This is the client part of flow. It is composed by two parts

• The flow client protocol, developed in java and compiled with GWT.
• An npm package that can be used as a JS library to use flow UI in any client app.

mvn clean package will do everything, and will leave a .jar file with everything set in the target folder.

Run mvn install or just mvn install -DskipTests

1. Install dependencies

Run either npm install or mvn compile

2. Compile Code and Run tests

Run either npm test or mvn test

3. Debug Tests

Run npm run debug then point your browser to http://localhost:9000/__intern/ to debug tests.

Since Vaadin 24.0, the Flow application can be run in so called Express Build mode, where the frontend files are pre-compiled and bundled into {project.root}/src/main/bundles directory. To make your changes in flow-client module be included into the Flow test modules, you have to delete this directory, so the Flow will re-compile the bundle and take into account your changes in flow-client:

• remove dev-bundle in the current folder: rm -rf src/main/bundles
• remove dev-bundle in the sub-folders: find . -type d -wholename "*/src/main/bundles" -exec rm -r {} +

In short debugging is building flow client JS in pretty/detailed mode and then adding it to your project and then using it for debugging in the browser.

1. git clone git@github.com:vaadin/flow.git
2. git checkout <appropriate branch/tag>
3. Build the project: mvn clean install -Dgwt.module.style=DETAILED -DskipTests in the flow-client folder.
   • -Dgwt.module.style=DETAILED - this can be on of the followings: DETAILED or PRETTY
   • -DskipTests - skipping tests is recommended, because tests are not needed for debugging and make the build process slower
   • Do not mind the many ERRORS happening while building the JAR, eventually build can be SUCCESS still,
   • the built JAR should be at the /target directory e.g. target/flow-client-X.Y-SNAPSHOT.jar
4. Make sure your project is using the non-obfuscated flow-client.jar:
   • Please make sure that your build tool config file (pom.xml or gradle.build) contains the proper information:
     • flow-client dependency in an application project points to the built version (e.g.: be sure it is X.Y-SNAPSHOT),
   • OR just uncompress the built JAR file and then copy the FlowClient.js from it to your proper directory (where it is served to frontend) in e.g.: frontend/generated/jar-resources
     • this option will make sure you use the non-obfuscated JS file (the other option can cause still some optimization)
5. Then you can debug the JS code in your browser's dev tools (e.g.sources tab: VAADIN/generated/jar-resources/FlowClient.js)

• you shall add the flow-client dependency if it is not present.
  • For example, your project may use Vaadin 24.2.0, but you rebuild the flow client at version 24.2-SNAPSHOT. In this case, you should probably add the flow-client dependency to overwrite the version the project is bringing in.
• Delete the dev-bundle (src/main/bundles) directory to be sure the project will not use a previously bundled version of the client
• clean the application project (mvn vaadin:clean-frontend or mvn:flow-clean-frontend) is also recommanded to be sure that you are using the rebuilt version of the Flow client.