Starting an Ark plug-in
Ark provides the interface for starting a plug-in com.alipay.sofa.ark.spi.service.PluginActivator. The definition of the interface is as follows:
public interface PluginActivator {
/**
* Start Plugin
* @param context plugin context
* @throws ArkException
*/
void start(PluginContext context) throws ArkException;
/**
* Stop Plugin
* @param context
* @throws ArkException
*/
void stop(PluginContext context) throws ArkException;
}
Once a plug-in implements this interface, and the activator attribute is configured in MANIFEST.MF, the plug-in will use the start method when it starts and the stop method when it stops.
Ark plug-in communication
Ark plug-ins communicate using services. The interfaces used by the publishing and reference services are provided in the input parameter type com.alipay.sofa.ark.spi.model.PluginContext of the preceding method of starting an interface.
/**
* Publish Plugin Service
* @param ifClass service interface
* @param implObject service implement object
* @param <T>
* @return
*/
<T> ServiceReference<T> publishService(Class<T> ifClass, T implObject);
/**
* Get Service publish by plugin, when there are multiple services, return the highest priority plugin service
* @param ifClass service interface
* @param <T>
* @return service reference
*/
<T> ServiceReference<T> referenceService(Class<T> ifClass);
/**
* Get Service publish by one specific plugin
* @param ifClass service interface
* @param <T>
* @param pluginName the name of the plugin which publish the service
* @return service reference
*/
<T> ServiceReference<T> referenceService(Class<T> ifClass, String pluginName);
/**
* Get Service List publish by plugin
* @param ifClass service interface
* @param <T>
* @return
*/
<T> List<ServiceReference<T>> referenceServices(Class<T> ifClass);
A plug-in service is interface-specific. For one interface, the following descriptions are true:
* Only one service can be published for each plug-in. When more than one service is published, the reference of the previously published service will be returned.
* If you use referenceService to reference a single service when multiple plug-ins have published services, which service is returned depends on whether pluginName is specified:
* When not specified, the service with the highest priority is returned.
* When specified, the service published by the plugin with the specified name is returned.
The returned service reference ServiceReference is defined as follows:
public interface ServiceReference<T> {
/**
* get Service Object
* @return service
*/
T getService();
/**
* get Service Metadata
* @return
*/
ServiceMetadata getServiceMetadata();
}
public interface ServiceMetadata {
/**
* get Service Unique Name
* @return service name
*/
String getServiceName();
/**
* get Service Interface Class
* @return interface class
*/
Class<?> getInterfaceClass();
/**
* get ServiceProvider
* @return
*/
ServiceProvider getServiceProvider();
}
Where:
* getService() can be used to obtain the service object (specifically, implObject is used when the service is published).
* getServiceMetadata() can be used to obtain the service metadata, including:
* Service name: interface name of the service
* Service interface
* Service provider information: includes provider name (such as the plugin name) and provider priority (plugin priority)