OSGi dependencies and versioning are important concepts in AEM when it comes to managing and using OSGi bundles. Here’s a detailed explanation of each concept:
Dependencies are the other OSGi bundles or services that a particular OSGi bundle requires in order to function properly. In AEM, we can specify the dependencies of an OSGi bundle using the “Import-Package” and “Require-Bundle” headers in the OSGi bundle manifest.
“Import-Package” header specifies the packages that are required by the bundle, but are not provided by the bundle itself. These packages are imported from other OSGi bundles.
“Require-Bundle” header specifies the required bundles that are needed by the bundle in order to function properly. These bundles are required to be available in the OSGi framework.
For example, let’s say we have an OSGi bundle that uses the Apache Sling Servlet API. To specify the dependency on the Apache Sling Servlet API, we can add the following header in the OSGi bundle manifest:
This header specifies that the “org.apache.sling.api.servlet” package is required by the OSGi bundle.
Versioning is the process of assigning a unique version number to an OSGi bundle or service. In AEM, we can specify the version of an OSGi bundle using the “Bundle-Version” header in the OSGi bundle manifest.
Versioning is important to ensure that different versions of the same bundle can coexist in the OSGi framework. The OSGi framework uses the version number to determine which version of a bundle to use when multiple versions are available.
For example, let’s say we have two versions of the same OSGi bundle, version 1.0.0 and version 1.1.0. To specify the version number in the OSGi bundle manifest, we can add the following header:
This header specifies that the version of the bundle is 1.1.0.
It’s important to note that when updating an OSGi bundle, the version number should be incremented to indicate the new version.