Apache Felix

Question 1

What is the @ Component annotation?

Answer 1

The @Component annotation is the only required annotation. If this annotation is not declared for a Java class, the class is not declared as a component.

This annotation is used to declare the element of the component declaration. See section 112.4.3, Component Element, in the OSGi Service Platform Service Compendium Specification for more information. The required element is automatically generated with the fully qualified name of the class containing the @Component annotation.

Question 2

What is the @ Service annotation?

Answer 2

The @Service annotation defines whether and which service interfaces are provided by the component. This is a class annotation.

This annotation is used to declare and elements of the component declaration. See section 112.4.6, Service Elements, in the OSGi Service Platform Service Compendium Specification for more information.

Question 3

what is the @ property annotation?

Answer 3

The @Property annotation defines properties which are made available to the component through the ComponentContext.getProperties() method. These tags are not strictly required but may be used by components to defined initial configuration. Additionally properties may be set here to identify the component if it is registered as a service, for example the service.description and service.vendor properties.

This annotation can be applied on the component class level or on a field defining a constant with the name of the property.

This annotation is used to declare elements of the component declaration. See section 112.4.5, Properties and Property Elements, in the OSGi Service Platform Service Compendium Specification for more information.