# Apache Karaf JPA Example ## Abstract This example shows how to use JPA with an entity. The entity manager is used in the persistence implementation. It implements a `BookingService` similar using a database for the storage, with a JPA entity. This example uses blueprint and declarative service to deal with JPA entity manager. The "command" bundle uses the `BookingService`. ## Artifacts * **karaf-jpa-example-provider** module contain: * **karaf-jpa-example-api** is a bundle providing the `Booking` entity used in the `BookingService`. As a best practice, this bundle should use a common bundle containing the `BookingService` interface, and then wrapping `Booking` POJO as a `JpaBooking` entity for instance. For convenience and reduce the number of example artifacts, we gather interface and implementation in the same bundle (again, it's bad). * **karaf-jpa-example-provider-blueprint** contain bundles providing EclipseLink and Hibernate implementation using blueprint. * **karaf-jpa-example-provider-ds** contain bundles providing EclipseLink and Hibernate implementation using declarative service. * **karaf-jpa-example-command** provides shell command to manipulate the `BookingService`. It use declarative service to retreive one instance of a `BookingService`. If you want to use several service provider, you have to stop the actual service and install the new one. * **karaf-jpa-example-features** provides a Karaf features repository used for the deployment. ## Build The build uses Apache Maven. Simply use: ``` mvn clean install ``` ## Feature and Deployment On a running Karaf instance, register the features repository using: ``` karaf@root()> feature:repo-add mvn:org.apache.karaf.examples/karaf-jpa-example-features/LATEST/xml ``` Then, you can install the datasource feature: ``` karaf@root()> feature:install karaf-jpa-example-datasource ``` Then, you can install the service command feature (commands booking:xxx will not be available until you have installed a provider): ``` karaf@root()> feature:install karaf-jpa-example-command ``` And install the service provider you want to use (for example EclipseLink using declarative service): ``` karaf@root()> feature:install karaf-jpa-example-provider-ds-eclipselink ``` ## Usage Once you have installed the feature, you can see new commands available in the Apache Karaf shell. `booking:add` command adds a new booking in the booking service. For instance: ``` karaf@root()> booking:add Doe AF520 ``` `booking:list` command lists the current bookings: ``` karaf@root()> booking:list ID │ Flight │ Customer ────────┼────────┼───────── 1 │ AF520 │ Doe ``` `booking:get` command get the booking with id: ``` karaf@root()> booking:get 1 ID │ Flight │ Customer ────────┼────────┼───────── 1 │ AF520 │ Doe ``` `booking:remove` command removes a booking from the booking service: ``` karaf@root()> booking:remove 1 ```