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Working on UI and apps


Front end applications are webcomponent based using the lit library and Material Design for styling. We use a combination of Polymer LIT, Material Design and our own OpenRemote elements. The UI components are published on NPM. The applications themselves are composed of our re-usable modular UI components which can be found in the code base in the ui/component folder, these are also published to NPM.

Working on an app (e.g. Manager UI)

To work on an app for example the Manager UI then cd into the app directory e.g. ui/app/manager and run the following npm script:

  • npm run serve - Compiles the typescript model from java code and then starts webpack dev server and serves the web app which can then be accessed at http://localhost:9000/manager/ (NOTE: trailing / is required)

Webpack dev server environment variables

The following environment variables can be set when running npm run serve using the syntax npm run serve -- --env ENV_NAME=ENV_VALUE:

  • config - To apply a custom manager_config.json you can set the config environment variable on the npm run serve command using a path relative to the app/manager directory e.g.
    • Windows: npm run serve -- --env config=..\..\..\..\deployment\manager\app
    • Mac: npm run serve -- --env config=../../../../deployment/manager/app
  • managerUrl - By default webpack dev server expects the manager to be available at http://localhost:8080 but this can be configured for example when running the manager Docker image (e.g. npm run serve -- --env managerUrl=https://localhost)
  • keycloakUrl - By default Keycloak expects to be available at managerUrl/auth but this can be configured for example when running the manager Docker image (e.g. npm run serve -- --env keycloakUrl=https://keycloak/auth)

Consuming UI components

Components are published as ES6 modules (for use in bundlers like webpack) and are also pre-bundled for direct consumption.

UI development

Doing development on the UI means working on any of:

  • Front end applications
  • Front end components and their demos, shared between applications
  • Keycloak theme(s) used in authentication screens

You will need the standard tool chain (see Preparing the environment to be able to build and run the components and apps. Working on the web applications and/or components will also generally require backend services to interact with, you can either:

If you want to create a new component or app then simply copy an existing one as a template (when creating a component then you may need to create a corresponding demo which acts as a development harness that can be served by webpack dev server - one demo may act as harness for multiple components).

UI Components & Apps (/ui)

All UI components and apps are located in the ui directory; here you can find the standard OpenRemote web UI components and apps using a monorepo architecture. The code is divided into categories by directory:

  • component - Base OpenRemote JS modules and web components (built using Polymer) these are written as ES6 modules
  • app - Built-in OpenRemote web applications (applications can be built with whatever frameworks/libraries are desired)
  • demo - Demos of each web component (provides a development harness for developers working on the components)

Typescript is used to provide static typing with the OpenRemote model available in the @openremote/model component package; the components are published to npm under the @openremote scope; see the README in each component for information about each specific component.

Yarn workspaces are used to symlink the OpenRemote packages into a root node_modules directory (refer to the Yarn documentation for more details). Yarn acts as an alternative to npm so please use it.

NPM scripts are used for build and development purposes (the main build tool for the entire code base is gradle so there are gradle tasks that launch NPM scripts - these gradle tasks have the prefix npm followed by the NPM script name e.g. npmBuild).

The following standard NPM scripts are used throughout the components and apps for consistency:

  • clean - Cleans up any build artefacts (typically uses the shx package)
  • build - Build the component/app ready for publishing/deployment
  • test - Run any automated tests
  • modelWatch - Starts a gradle task to watch the java model code and to run the typescript generator when changes are detected, the generated model and restclient typescript code is then transpiled to javascript
  • modelBuild - Similar to modelWatch but just does a onetime build rather than watching for changes
  • serve - Starts webpack dev server typically on http://localhost:9000/[app|demo]/

The above script names should be used in package.json files and then appropriate build.gradle files should be added, see existing components, apps, demos for examples. Typically only the apps need to be built by gradle tasks as typescript should follow project references and compile any dependent components.


Components can be developed and tested in isolation (with dependencies on other components and/or public npm modules as required). Some components have no visuals and provide standard OpenRemote functionality e.g. @openremote/core, whilst others provide visuals that allow interaction with the Manager backend.


If you are working on a map component then please refer to the working on maps.


Apps bring together components and/or public NPM modules and can be written using any framework/library etc that is compatible with web components (see here).


These are apps for development purposes Generally a 1-1 mapping between components and demos; they provide a simple harness for the components that can be used during development and optionally can be deployed to offer component demos.

Publishing to NPM

Publishing is done using lockstep versioning; we use yarn version plugin to manage workspace package version incrementing as follows:

  1. The public packages are marked for version bump: yarn workspaces foreach --no-private --topological version --deferred <patch | minor | major>
  2. The new versions are applied: yarn version apply --all
  3. The components are prepared: yarn workspaces foreach --no-private --topological npm prepublishOnly
  4. The public packages are packed and published: yarn workspaces foreach --no-private --topological npm publish