Akka HTTP with Scala.js

This is a simple example application showing how you can integrate an Akka HTTP project with a Scala.js project.

The application contains three directories:

• server Akka HTTP application (server side)
• client Scala.js application (client side)
• shared Scala code that you want to share between the server and the client

Run the application

$ sbt
> ~re-start
$ open http://0.0.0.0:8080

Features

The application uses the sbt-web-scalajs sbt plugin and the scalajs-scripts library.

• compile, run, re-start trigger the Scala.js fastOptJS command
• ~compile, ~run, ~re-start continuous compilation is also available
• Production archives (e.g. using assembly, universal:packageBin) contain the optimised javascript
• Source maps
  • Open your browser dev tool to set breakpoints or to see the guilty line of code when an exception is thrown
  • Source Maps is disabled in production by default to prevent your users from seeing the source files. But it can easily be enabled in production too by setting emitSourceMaps in fullOptJS := true in the Scala.js projects.

Cleaning

The root project aggregates all the other projects by default. Use this root project, called akka-http-with-scalajs-example, to clean all the projects at once.

$ sbt
> akka-http-with-scalajs-example/clean

IDE integration

Eclipse

1. $ sbt "eclipse with-source=true"
2. Inside Eclipse, File/Import/General/Existing project..., choose the root folder. Uncheck the first and the last checkboxes to only import client, server and one shared, click Finish.

IntelliJ

In IntelliJ, open Project wizard, select Import Project, choose the root folder and click OK. Select Import project from external model option, choose SBT project and click Next. Select additional import options and click Finish. Make sure you use the IntelliJ Scala Plugin v1.3.3 or higher. There are known issues with prior versions of the plugin.

Classpath during development

The assets (js files, sourcemaps, etc.) are added to the classpath during development thanks to the following lines:

WebKeys.packagePrefix in Assets := "public/",
managedClasspath in Runtime += (packageBin in Assets).value

Note that packageBin in Assets also executes any tasks appended to pipelineStages, e.g. gzip. You may want to avoid executing tasks under pipelineStages during development, because it could take long to execute.

In that case, in order to still have access to the assets under WebKeys.packagePrefix in Assets during development, you can use the following code instead:

lazy val server = (project in file("server")).settings(
...
WebKeys.packagePrefix in Assets := "public/",
WebKeys.exportedMappings in Assets ++= (for ((file, path) <- (mappings in Assets).value)
  yield file -> ((WebKeys.packagePrefix in Assets).value + path)),
...
)