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2.2. Sample OSGi Application

Example of bundle dependencies

Figure 2.2, “Sample OSGi Application” shows an overview of a sample OSGi application consisting of five bundles, which illustrates the basic bundle types discussed in the previous section. The application is driven by the hello-consumer bundle, which imports a HelloParis service from the hello-paris bundle and imports a HelloBoston service from the hello-boston bundle.

Figure 2.2. Sample OSGi Application

Sample OSGi Application

The sample bundles

The sample OSGi application consists of the following bundles:
time-util
Fits the pattern of a library bundle. The time-util bundle is a utility library that can create Clock instances that tell the time in a particular time zone.
The time-util bundle is implemented using classes from the JDK and thus has no external package dependencies.
hello-paris
Fits the pattern of an API bundle. The hello-paris bundle consists of a single Java interface, which returns a greeting, getGreeting(), and gives the local time in Paris, getLocalTime().
The hello-paris bundle has the following external package dependency: 
org.fusesource.example.time
hello-paris-impl
Fits the pattern of a provider bundle. The hello-paris-impl bundle implements the hello-paris API bundle.
The hello-paris-impl bundle has the following external package dependencies: 
org.fusesource.example.hello.paris
org.fusesource.example.time
hello-boston
Fits the pattern of an API/provider combination bundle. The hello-boston bundle combines a Java interface and its implementation, where the Java interface returns a greeting, getGreeting(), and gives the local time in Boston, getLocalTime().
The hello-boston bundle has the following external package dependency: 
org.fusesource.example.time
hello-consumer
Fits the pattern of a consumer bundle. The hello-consumer bundle imports the HelloParis OSGi service and the HelloBoston OSGi service and then invokes on these services to report the local times in Paris and in Boston.
The hello-consumer bundle has the following external package dependencies: 
org.fusesource.example.hello.paris
org.fusesource.example.hello.boston
org.fusesource.example.time