Calling Non-OSGi Code that Uses OSGi Services

Liferay DXP’s static utility functions (e.g., UserServiceUtil, CompanyServiceUtil, GroupServiceUtil, etc.) are examples of non-OSGi code that use OSGi services.

Note that it’s safer to track and use Liferay DXP’s OSGi services directly with Liferay DXP’s Registry API than to invoke Liferay DXP’s similar static utility functions. For example, you can’t call an OSGi service unless all its dependencies are satisfied: the container won’t enable the service. If you invoke Liferay DXP’s static utility functions, you might invoke them prematurely (e.g., before OSGi bundle activation and application startup events). You could work around this by identifying all of the implied OSGi service dependencies and making sure they are satisfied before invocation, but then you’re not only duplicating the container’s more robust functionality for this, you’re also creating a bigger surface for bugs. Avoid this mess by using Liferay DXP’s Registry API to track the services you want. This way, you let OSGi make sure a service’s dependencies are satisfied before invoking that service. For example, use Liferay DXP’s OSGi service UserService instead of UserServiceUtil, which in turn uses the OSGi service UserService. Click here to see an example of this.

Remember that you can check the state of Liferay DXP’s services in the Gogo shell. If you’re running Liferay DXP locally, use the command telnet localhost 11311 to connect to the Gogo shell. Once connected, the scr:list command shows all Declarative Services components, including inactive ones from unsatisfied dependencies. To find unsatisfied dependencies for Service Builder services, use the Dependency Manager’s dependencymanager:dm wtf command. Note that these commands only show components that haven’t been activated because of unsatisfied dependencies–they don’t show pure service trackers that are waiting for a service because of unsatisfied dependencies.

Using OSGi Services from EXT Plugins

Detecting Unresolved OSGi Components

Felix Gogo Shell

OSGi Basics For Liferay Development

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