Embedding a JavaScript Service enables to use both the JavaScript language and Java methods by importing their classes.

Let us rewrite the twice service example as a JavaScript embedded service.

importClass( java.lang.System );
importClass( java.lang.Integer );

function twice( request )
    var number = request.getFirstChild("number").intValue();
    System.out.println( "Received a 'twice' request for number: " + number );
    return Integer.parseInt(number + number);

At Lines 1-2 we respectively import java.lang.System to use it for printing at console a message, and java.lang.Integer to send a proper response to the embedder. This is necessary because of JavaScript's single number type which, internally, represents any number as a 64-bit floating point number. At Line 6 the methods getFirstChild and intValue, belonging to Value class, are used to read the request's data. Finally at Line 8 we use the parseInt method of class Integer to return an Integer value to the invoker.

include "console.iol"

type TwiceRequest:void {
    .number: int

interface TwiceInterface {
    twice( TwiceRequest )( int )

outputPort TwiceService {
Interfaces: TwiceInterface

embedded {
    "TwiceService.js" in TwiceService

    request.number = 5;
    twice@TwiceService( request )( response );
    println@Console( "Javascript 'twice' Service response: " + response )()

Like embedding Jolie Services, also JavaScript Services require the specification of the local file where the JavaScript Service is defined (i.e., TwiceService.js, Line 18).