OSGi is specification and set of standards to develop Java based modular applications.
1. OSGi Framework : It is runtime (OSGi Container) & development environment.
2. Bundle : Basic unit to deploy into the OSGi container. It is a JAR file which contains executable code and OSGi headers in its MANIFEST.MF file.
Bundle = MANIFEST.MF + Java classes + Resources.
a. Symantic versioning : Major . Minor . Micro - Qualifier (3.0.0-BETA).
Eg. [1.2, 3.0) (means version 1.2 onwards and upto 3.0 not included 3.0 version)
b. Bundle lifecycle managed by BundleActivator.
States are :
1. installed (after added into the container), 2. Resolved (all imported dependencies are resolved ), 3. Starting, 4. Active, 5. Stopping, 6. Unistalling.
3. Component : It is an object (java class) which has set of functionalities. It is managed by component framework.
Component Lifecycle : 1. active, 2. activated. 3. deactivated
4. Service : It is a component registered to OSGi Container 'service registry'.
Implements an interface and referenced by its interface in the OSGi Container.
