In an embedded environment, Derby runs in the same JVM as the application.
The application can be a single-user application or a multi-user application server. In the latter case, Derby runs embedded in the user-provided server framework, and any client applications use user-provided connectivity or allow the application server to handle all database interaction.
The following figure shows Derby embedded in a single-user Java application.
The following figure shows Derby embedded in a multi-user Java application server.
When a Derby database is embedded in a Java application, the database is dedicated to that single application. If you deploy more than one copy of the application, each application has its own copy of the database and Derby software. A Derby server framework can work in multi-threaded, multi-connection mode and can even connect to more than one database at a time. A server framework, such as the Derby Network Server, can be used to manage multiple connections and handle network capabilities. Some server framework solutions, such as WebSphere Application Server, provide additional features such as web services and connection pooling. However, only one server framework at a time can operate against a Derby database.
The Derby application accesses an embedded Derby database through the JDBC API. To connect, an application makes a call to the local Derby JDBC driver. Accessing the JDBC driver automatically starts the embedded Derby software. The calling application is responsible for shutting down the embedded Derby database software.