See an example of stateless bean definition:
package boxdata.ejb
import boxdata.data.dto.DeviceUsageDto
import scala.collection.JavaConverters._
import javax.ejb.EJB
import javax.ejb.Stateless
@Stateless
class DeviceUsageEjb {
@EJB
var disk: DiskUsageEjb = _
@EJB
var file: FileUsageEjb = _
def getUsage: DeviceUsageDto = {
val diskUsage = disk.getUsage
val fileUsage = file.getUsage
val dto = new DeviceUsageDto
dto.diskUsageList = diskUsage.asJava
dto.fileUsageList = fileUsage.asJava
dto
}
}
Notice the usage of the JavaEE annotations ("@Stateless" and "@EJB").
How would we define a rest application?
package boxdata.rest
import javax.ws.rs.ApplicationPath
import javax.ws.rs.core.Application
import java.util
import scala.collection.JavaConverters._
@ApplicationPath("/rest")
class ApplicationConfig extends Application {
override def getClasses: util.Set[Class[_]] = {
Set[Class[_]](
classOf[DeviceUsage],
classOf[SystemLoad],
classOf[SystemThreads]
).asJava
}
}
You don't need to download and install Scala before using it with TomEE. Maven takes care of everything. With Maven, the war generation is as simple as "mvn clean install". The resulting war will have only two jars: scala-library-2.9.2.jar and boxdata-web-1.0-SNAPSHOT.jar.
See what "boxdata-web-1.0-SNAPSHOT.jar" contains:
128 Tue Apr 16 14:34:24 EDT 2013 META-INF/MANIFEST.MF
663 Tue Apr 16 14:34:12 EDT 2013 META-INF/ejb-jar.xml
827 Tue Apr 16 14:34:12 EDT 2013 META-INF/beans.xml
2727 Tue Apr 16 14:34:24 EDT 2013 boxdata/data/dto/DiskUsageDto.class
4145 Tue Apr 16 14:34:24 EDT 2013 boxdata/data/dto/ThreadDto.class
6451 Tue Apr 16 14:34:24 EDT 2013 boxdata/data/dto/SystemLoadDto.class
2518 Tue Apr 16 14:34:24 EDT 2013 boxdata/data/dto/DeviceUsageDto.class
1915 Tue Apr 16 14:34:24 EDT 2013 boxdata/data/dto/FileUsageDto.class
1977 Tue Apr 16 14:34:24 EDT 2013 boxdata/rest/SystemLoad.class
1464 Tue Apr 16 14:34:24 EDT 2013 boxdata/rest/DeviceUsage.class
2006 Tue Apr 16 14:34:24 EDT 2013 boxdata/rest/SystemThreads.class
1915 Tue Apr 16 14:34:24 EDT 2013 boxdata/rest/ApplicationConfig.class
3298 Tue Apr 16 14:34:24 EDT 2013 boxdata/ejb/SystemThreadsEjb.class
12153 Tue Apr 16 14:34:24 EDT 2013 boxdata/ejb/SystemThreadsEjb$$anonfun$getThreadsInfo$1.class
2308 Tue Apr 16 14:34:24 EDT 2013 boxdata/ejb/DeviceUsageEjb.class
1877 Tue Apr 16 14:34:24 EDT 2013 boxdata/ejb/FileUsageEjb$$anonfun$buildUsage$1.class
5115 Tue Apr 16 14:34:24 EDT 2013 boxdata/ejb/SystemLoadEjb.class
2736 Tue Apr 16 14:34:24 EDT 2013 boxdata/ejb/SchedulerEjb.class
12043 Tue Apr 16 14:34:24 EDT 2013 boxdata/ejb/DiskUsageEjb$$anonfun$getUsage$1.class
4070 Tue Apr 16 14:34:24 EDT 2013 boxdata/ejb/FileUsageEjb.class
2395 Tue Apr 16 14:34:24 EDT 2013 boxdata/ejb/DiskUsageEjb.class
3823 Tue Apr 16 14:34:24 EDT 2013 boxdata/cdi/util/DtoBuilder.class
2346 Sat Apr 13 09:17:58 EDT 2013 META-INF/maven/boxdata/boxdata-web/pom.xml
110 Tue Apr 16 14:34:26 EDT 2013 META-INF/maven/boxdata/boxdata-web/pom.properties
For more details about how to build a JavaEE application with Scala, nothing better than checking a real code. Go ahead and clone the https://github.com/tveronezi/boxdata. This project is a starting point for your own applications with TomEE and Scala. For those who love Javascript, the example also shows how to integrate ExtJS and Highcharts.
 |
| Application output |
 |
| Intellij with Scala code (plugin website) |
If you are a windows user, you will need to download the bleeding-edge version of TomEE in order to run this application (See how to build and run it with Intellij in this blog post). If you are a Unix-like OS user, you can execute the "make start-tomee" makefile target (check the README file).
Have fun with JavaEE and TomEE!
Ps.: Check out the other JavaEE Scala application -> http://buildnplay.blogspot.ca/2013/06/ejb-mdb-rest-jpa-cdi-all-javaee-fun.html
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