Programming Open Service Gateways with Java Embedded Server

With an emphasis on actual coding, this definitive guide begins by explaining the backdrop in which the residential gateway market emerged. Next, the book discusses the history and mission of the Java Embedded Server product and the OSGi consortium. Throughout the book, the Java Embedded Server technical architecture and the OSGi Service Gateway API are presented with examples and detailed implementations. The book's practical, how-to format shows you how to write code for residential gateway applications that is correct, robust, and efficient while avoiding common traps and pitfalls.

Highlights include:

• Overview of OSGi architecture, including basic concepts and features
• How to install Java Embedded Server and develop service bundles
• Design patterns and pitfalls
• How to use the OSGi standard services: log service and HTTP service
• OSGi Device Access (DA) service
• Permission-based security and administration
• The future undertakings of the OSGi consortium
• The OSGi Service Gateway SpecificatProgramming Open Service Gateways with Java Embedded Server™ Technology gives you an insider's perspective on the development process of new applications and services for the residential gateway environment.

  Contents

  Preface.
  Acknowledgments.
  1. Introduction.
  

  The Internet and the Networked Home.
  The Service Gateway.
  Challenges.
  

  A Multitude of Competing Solutions.
  A New Application Environment.
  

  
  Java Embedded Server Technology.
  The Open Services Gateway Initiative.
  Operational Model.
  
  
  2. Getting Started.
  
  Setting Up the Java Embedded Server Software.
  The "Home, Sweet Home" Bundle.
  

  Create the Directory.
  Define the Manifest.
  Write an Activator.
  Compile the Activator Class.
  Pack Up.
  

  
  Running the Bundle.
  

  Getting Help.
  The Cache Directory.
  The Bundle Base URL.
  Brief Summary of the Major Commands.
  

  
  
  
  3. Architecture and Basic Concepts.
  
  Motivation.
  Architecture.
  Service.
  Bundle.
  

  A Bundle Is a Packaging Vehicle.
  A Bundle Is a Functional Module.
  The "Hooks" to the Framework.
  

  
  The Framework.
  Cooperation among Bundles and Services.
  

  Exporting and Importing Packages.
  Registering and Obtaining Services.
  Package versus Service Dependency.
  

  
  Life within the Framework.
  

  Installing a Bundle.
  Starting the Bundle.
  Importing Packages and Getting Services.
  Handling the Dynamic Service Dependency.
  Updating a Bundle.
  Stopping and Uninstalling a Bundle.
  

  
  The Component-based Model.
  Forget CLASSPATH.
  
  
  4. Developing Bundles.
  
  Writing Service Bundles.
  

  Design the Service Interface.
  Implement the Service.
  Register the Service in the Activator.
  Define the Manifest Headers.
  Create the Bundle.
  

  
  Same Service Interface, Different Implementations.
  Retrieving Resources from within the Bundle.
  Obtaining and Calling Registered Services.
  

  Interbundle Dependency and Class Loading Issues.
  Service Use Count.
  Compiling Client Bundles.
  

  
  Service Factory.
  

  Producing a Customized Service for Each Client Bundle.
  Service Cache.
  Customization for Getting and Releasing Service.
  

  
  Relevant org.osgi.framework APIs.
  

  BundleContext Interface.
  ServiceReference Interface.
  ServiceRegistration Interface.
  

  
  Library Bundles.
  Advanced Examples.
  

  A Mailer.
  A Line Printer Daemon Print Service.
  

  
  Writing Bundles That Contain Native Code.
  

  Common Mistakes.
  Activator.
  Manifest.
  Creating a JAR File.
  

  
  
  
  5. Cooperation among Service Bundles.
  
  Event Handling.
  Bundle State and Service Registration.
  Synchronous and Asynchronous Events.
  Dealing with Service Unregistration.
  

  Don't Start without the Service.
  Discovering Stale Service.
  Carrying On without the Service.
  Picking an Alternative.
  Cascading Service Registration.
  Refusing Service.
  

  
  Cooperation with Asynchronous Events.
  
  
  6. Design Patterns and Pitfalls.
  
  Designing the Service.
  

  Separating Service Interface and Implementation.
  Challenges in Designing a Service Interface.
  Approaching an Interface Design.
  The Social Aspect.
  

  
  Designing Library Bundles.
  Delegation and Callback.
  Leveraging the Service Registry.
  Threading.
  

  Preventing Runaway Threads.
  Writing a Multithread Server Bundle.
  Using a Thread Pool.
  

  
  Managing Object Allocation.
  

  Nullify References After Use.
  Managing References among Bundles.
  

  
  
  
  7. Standard Services.
  
  The Log Service.
  

  Using LogService to Write Logs.
  Using LogReaderService to Get Logs.
  Performing Persistent Logging.
  

  
  The HTTP Service.
  

  The Standard HttpService API.
  Performing Basic Authentication.
  The Extended HTTP Service.
  

  
  
  
  8. Device Access.
  
  Introduction.
  

  The Software Stack in Device Access.
  What Device Access Is Not.
  

  
  Motivation.
  Cast of Characters.
  

  Device Service.
  Driver Services.
  Driver Locator.
  Device Manager.
  

  
  Writing DA Services.
  

  The Base Driver.
  Device Detection.
  Device Refinement.
  The Reconfiguration Process.
  

  
  Putting It Together.
  
  
  9. Permission-based Security and Administration.
  
  Permission-based Security inside the Java 2 Platform.
  

  Code Source.
  Permission.
  Policy.
  Granting Permissions to Classes.
  Security Manager.
  

  
  OSGi Permissions.
  

  AdminPermission.
  ServicePermission.
  PackagePermission.
  Permission Required by the Framework APIs.
  

  
  Enabling Security.
  

  Setting Up a Policy.
  Running with Security Enabled.
  

  
  Using Permissions in Your Service.
  

  Checking Permissions.
  Performing Privileged Actions.
  Creating Your Own Permission Types.
  

  
  Administration.
  

  Resolving Bundles Dynamically.
  Relevant APIs.
  

  
  
  
  10. Future Directions.
  
  Removing Phantom Bundles.
  Dynamic Permissions.
  Preferences.
  User Administration.
  Configuration Management.
  What's Next.
  
  
  Appendix A. Code Examples.
  
  Chapter 4—Developing Bundles.
  

  The LPD Print Service.
  

  
  Chapter 8—Device Access.
  

  Serial Service and Driver Locator.
  Driver Service and Modem Service.
  Web Interface to the Serial Ports.
  

  
  Chapter 9—Permission-based Security and Administration.
  

  Parameter Services.
  Parameter Configuration Servlet.
  Facilitator.
  

  
  
  
  Appenidix B. OSGi Service Gateway Specification.
  
  org.osgi.framework.
  AdminPermission.
  Bundle.
  BundleActivator.
  BundleContext.
  BundleEvent.
  BundleException.
  BundleListener.
  Configurable.
  FrameworkEvent.
  FrameworkListener.
  InvalidSyntaxException.
  PackagePermission.
  ServiceEvent.
  ServiceFactory.
  ServiceListener.
  ServicePermission.
  ServiceReference.
  ServiceRegistration.
  org.osgi.service.device.
  Device.
  Driver.
  DriverLocator.
  org.osgi.service.http.
  HttpContext.
  HttpService.
  NamespaceException.
  org.osgi.service.log.
  LogEntry.
  LogListener.
  LogReaderService.
  LogService.
  
  
  Bibliography.
  Index.