Service Activator Toolkit

Tutorial 1: Exporting and Importing Services

The goal of this tutorial is to teach the use of the Service Activator Toolkit through the development of some simple service-oriented bundles. The tutorial is simple and focuses on understanding how best to use SAT to build service-oriented bundles rather than teaching OSGi.

After completing this tutorial you will have an understanding of how to build service-oriented bundles with SAT, how to register exported services, and how to acquire imported services.

The Prerequisites

Before you start this tutorial you should have:

An understanding of the capabilities of the OSGi Service Platform and the OSGi service registry. Details of the OSGi Service Platform can be found at the OSGi Alliance.
Installed the SAT runtime bundles.
An understanding of how to use the Plug-in Development Environment (PDE) tooling to create a plug-in project, manage a plug-in project's metadata files using the manifest editor, and how to launch the Equinox OSGi framework from within the Eclipse IDE.

The Vendor Application

The diagram on the right shows the topology of the tutorial application.

Starting at the bottom of the diagram, the yellow Vendor Service bundle is a library bundle that exports a package into the OSGi framework. The package contains the Java interface VendorService.
Both the green Hotdog Vendor bundle and the Popcorn Vendor bundle import the package that is exported by the Vendor Service bundle, since they have Java code dependencies on the VendorService interface.
Both the green Hotdog Vendor bundle and Popcorn Vendor bundle register an implementation of the VendorService with the OSGi framework.
The blue Customer bundle is a leaf bundle since it is at the top of the bundle food chain. The Customer bundle imports the package exported by the Vendor Service bundle since it has Java code dependencies on the VendorService interface.
The blue Customer bundle acquires an implementation of the VendorService from the OSGi framework. The Customer bundle does not, and should not, care whether it acquires the Hotdog Vendor or the Popcorn Vendor implementation of the service.

The Steps

This tutorial consists of the following steps:

Creating the Vendor Service Bundle: In this step the Vendor Service library bundle is created that exports a package that contains the VendorService interface. Other bundles will create implementations of this interface and register them with the OSGi framework, while others will acquire an implementation of this interface from the OSGi framework.
Creating the Hotdog Vendor Bundle: In this step the Hotdog Vendor bundle is created that imports the package containing the VendorService interface and registers an implementation of the service with the OSGi framework.
Creating the Popcorn Vendor Bundle: In this step the Popcorn Vendor bundle is created that also imports the package containing the VendorService interface and registers an implementation of the service with the OSGi framework.
Creating the Customer Bundle: In this step the Customer bundle is created that imports the package containing the VendorService interface and acquires an implementation of the interface from the OSGi framework.
Launching the Vendor Application: In this step the Equinox OSGi Framework will be launched with our application bundles installed and started.
Testing the Vendor Application: In this step the application will be tested using the OSGi console commands.

Source Projects

The source projects for this tutorial are available as a zip file that may be extracted into the file system and imported into your Eclipse workspace.

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