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SCA/SCA Component/SCA First Steps With Composite Designer

Revision as of 10:15, 26 May 2008 by (Talk | contribs) (Test the Restaurant)

The objective of this tutorial is to show how to develop a simple SCA application using the STP/SCA Composite Designer.

You can download a pdf version of this tutorial: "First Steps with the SCA Composite Designer".

The tutorial illustrates how to:

  • Install the STP/SCA plugins and Apache Tuscany
  • Define an SCA assembly with the SCA Composite Designer
  • Refine properties in an SCA assembly
  • Define an SCA assembly with different implementation technologies
  • Define an RMI binding
  • Run and test SCA assemblies with Tuscany


In order to be able to test the sample SCA application, you need to :

  • install Apache Tuscany on your machine,
  • set up Eclipse for Tuscany.

The SCA Restaurant Application

The following figure shows the SCA assembly of the application that you will create. RestaurantOverview.png

This composite, named restaurant, is a composition of five components:

Allows you to see the Menus proposed by the restaurant.
It allows also to compute the bill for a particular menu.
Provides different menus. A Menu is defined by a description and the price without taxes.
Computes the price of a menu with the different taxes.
Computes the VAT (Value Added Tax).
Computes the tip.

First SCA Application

Create a new Java Project

First, create a Java Project to hold the Restaurant application:

  1. Select File > New > Java Project.
  2. Set "Restaurant" as the Project name. For Project layout, select Create separate folders for sources and class files. Click on the Next button.
  3. Click on the Finish button.

Create a new SCA Composite diagram

To create an SCA diagram:

  1. Right-click the project and select New > Other....
  2. In the New wizard, select SCA Composite Diagram in the SCA Tools folder (Other folder if there is no SOA Tools folder) and click Next.
  3. Choose a folder and type a unique name for the diagram in the File name field and click Finish.

The new created file is automatically open with the SCA Composite Designer. To open the Properties view, do a right click on the diagram and the select Show Properties View. Restaurant1.PNG

In accordance with the SCA specifications, the composite and the composite file have the same name. The name of the composite is automatically set

Now, you should see the following project structure:


Create a Restaurant Composite

Add a first component named RestaurantServiceComponent. You can do it with the Component creation tool which is in the palette or using the contextual menu.

Palette.PNG ContextualMenuNewComponent.PNG

Then, add MenuServiceComponent, BillServiceComponent, VatServiceComponent, and TipServiceComponent.

Next, add the following services:

  • a service named RestaurantService on the RestaurantServiceComponent,
  • a service named MenuService on the MenuServiceComponent,
  • a service named BillService on the BillServiceComponent,
  • a service named VatService on the VatServiceComponent,
  • a service named TipService on the TipServiceComponent.

In the next step, add the following references:

  • a reference named menuReference on the RestaurantServiceComponent,
  • a reference named billReference on the RestaurantServiceComponent,
  • a reference named vatReference on the BillServiceComponent,
  • a reference named tipReference on the BillServiceComponent.

Now you can wire the services and references. From the palette, you can use :

  • the Wire creation tool: a Wire element is added,
  • the Wire target: target attribut of the Reference element is used.

The next step is to promote the restaurant service. Two ways are possible to promote a service (or a reference). You can:

  • create a new Service on the composite and then use the Promote creation tool from the palette to add a promotion link between the composite service and the promoted component service, or
  • right-click a component service, and select Promote menu item.


Save your diagram. The Restaurant.composite_diagram contains the graphical part of your SCA assembly and the Restaurant.composite file contains the XML code that describes your SCA assembly.

You can open the Restaurant.composite file with the SCA Composite Model Editor. Right-click the Restaurant.composite file, select Open with > SCA Composite Model Editor. A multi page editor is opened. It offers a tree view and the source code of your SCA assembly. You can modify your SCA assembly with these two editors. They are synchronized with the SCA Composite Designer.

RestaurantTreeEditor.PNG RestaurantSourceEditor.PNG

Define interfaces and implementations

First, in the src directory of the Restaurent project create a new package named restaurant with two sub-packages named api and lib.


Define the interfaces of the services (restaurant.api package):

  • Restaurant Service
package restaurant.api;
public interface RestaurantService { 
  Menu[] getMenus();
  double getBill(Menu menu);
  • Menu Service
package restaurant.api;
public interface MenuService {
  Menu[] getMenu();
  double getPrice(Menu menu);
  • Bill Service
package restaurant.api;
public interface BillService {
  double getBill(double menuPrice);
  • Vat Service
package restaurant.api;
public interface VatService {
  double getPriceWithVat(double price);
  • Tip Service
package restaurant.api;
public interface TipService {
  double getPriceWithTip(double price);

Define also the interface of the Menu (Data Transfert Object):

package restaurant.api;
public interface Menu extends Serializable {
  String printMenu();

Next, define the implementations (restaurant.lib package).

  • Restaurant Service
package restaurant.lib;
import restaurant.api.BillService;
import restaurant.api.Menu;
import restaurant.api.MenuService;
import restaurant.api.RestaurantService;
public class RestaurantServiceImpl implements RestaurantService {
  private MenuService menuService;
  private BillService billService;
  public void setMenuService(MenuService menuService) {
    this.menuService = menuService;
  public void setBillService(BillService billService) {
    this.billService = billService;
  public double getBill(Menu menu) {
    double menuPrice = this.menuService.getPrice(menu);
    return this.billService.getBill(menuPrice);
  public Menu[] getMenus() {
    return this.menuService.getMenu();
  • Menu Service
package restaurant.lib;
import restaurant.api.Menu;
import restaurant.api.MenuService;
public class MenuServiceImpl implements MenuService {
  private Menu[] menus;
  private double[] prices;
  public void init() {
    this.menus = new Menu[] {
            new MenuImpl(0, "Grilled hamburger with French fries" ),
            new MenuImpl(1, "Roasted chicken with vegetables"),
            new MenuImpl(2, "Duck breast in an orange sauce"),
            new MenuImpl(3, "Duck foie gras & mango chutney") };
    this.prices = new double[] { 10, 15, 35, 50 };
  public Menu[] getMenu() {
    return this.menus;
  public double getPrice(Menu menu) {
    return this.prices[((MenuImpl) menu).getId()];
  • Bill service
package restaurant.lib;
import restaurant.api.BillService;
import restaurant.api.TipService;
import restaurant.api.VatService;
public class BillServiceImpl implements BillService {
  private VatService vatService;
  private TipService tipService;
  public void setVatService(VatService vatService) {
    this.vatService = vatService;
  public void setTipService(TipService tipService) {
    this.tipService = tipService;
  public double getBill(double menuPrice) {
    double pricewithTaxRate = 
    double priceWithTipRate = 
    return priceWithTipRate;
  • Vat Service
package restaurant.lib;
import restaurant.api.VatService;
public class VatServiceImpl implements VatService {
  public double vatRate;
  public VatServiceImpl(){
  public double getPriceWithVat(double price) {
    return price * this.vatRate/100 + price;
  • Tip service
package restaurant.lib;
import restaurant.api.TipService;
public class TipServiceImpl implements TipService {
  public double tipRate;
  public TipServiceImpl(){
  public double getPriceWithTip(double price) {
    return price * this.tipRate/100 + price;
  • Menu
package restaurant.lib;
import restaurant.api.Menu;
public class MenuImpl implements Menu {
  private int id;
  private String details;
  MenuImpl(int idC, String detailsC) { = idC;
    this.details = detailsC;
  public String printMenu() {
    return this.details;
  public int getId() {

Now, you can fill you SCA assembly file with the interfaces and implementations that you defined. Open the Restaurant.composite_diagram with the SCA Composite Designer.

You have two ways to fill your SCA assembly file:

  • Drag and drop the Java interface files on the services of your diagram and the Java implementation files on the components. The name of these elements are automatically set.


  • Use the JavaInterface and the JavaImplementation creation tools from the palette or the contextual menu. For each created element, you must set (in the Properties view):
    • the Interface attribute for a Java interface, and
    • the Class attribute for a Java implementation.


Now, your SCA assembly diagram looks like: RestaurantWithImplemAndInterface.PNG

and, your SCA assembly file looks like: SCAAssemblyFileWithImplemAndInterface.PNG

Right-clik your diagram (on the Canvas part = white part of your diagram), the contextual menu allows:

to validate your diagram, and to hide/show implementation, interface and binding icons. RightClick.PNG

You have finished developping your first SCA application with the SCA Composite Designer. It is time to test.

Test the Restaurant

Create a new Package, named test, in the src folder of your porject. Create a new Java class named Client:

package test;
import restaurant.api.Menu;
import restaurant.api.RestaurantService;
public class Client {
  public static void main(String[] args) throws Exception {
    SCADomain scaDomain = SCADomain.newInstance("Restaurant.composite");
    RestaurantService restaurantService = scaDomain.getService(
    RestaurantService.class, "RestaurantServiceComponent");
    Menu[] menus = restaurantService.getMenus();
    System.out.println("--- Menu ---");
    for (Menu m : menus) {
      System.out.println("- " + m.printMenu());
    Menu menu = menus[3];
    System.out.println("My choice: " + menu.printMenu());
    double price = restaurantService.getBill(menu);
    System.out.println("Price (" + menu.printMenu() + "): " + price);

Lauch the client:

  1. Do a right-click on the Client class.
  2. Select Run as > Java Application.

In the Console view you should see: RestaurantConsoleResult.PNG

Refine a property

Change Implementation and bindings

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