G Oracle CEP Metadata Annotation Reference

G.1 Overview of Oracle CEP Metadata Annotations

Oracle CEP metadata annotations are used to access the configuration of an Oracle CEP component. Oracle CEP offers the following annotations:

• Section G.1.1, "Adapter Lifecycle Annotations"

• Section G.1.2, "OSGi Service Reference Annotations"

• Section G.1.3, "Resource Access Annotations"

For more information, see:

• Section 1.1.8, "Oracle CEP Application Lifecycle"

• Section 1.6, "Configuring Oracle CEP Resource Access"

G.2 com.bea.wlevs.configuration.Activate

Target: Method

The @Activate annotation is one of the adapter lifecycle annotations that you use in the Java file that implements your custom adapter to explicitly specify the methods that Oracle CEP uses to send configuration information to the adapter.

Oracle CEP calls methods marked with the @Activate annotation after, and if, the server has called and successfully executed all the methods marked with the @Prepare annotation. You typically use the @Activate method to actually get the adapter's configuration data to use in the rest of the adapter implementation.

The method you annotate with this annotation must have the following signature:

public void methodName(AdapterConfigObject adapterConfig)

where methodName refers to the name you give the method and AdapterConfigObject refers to the Java representation of the adapter's configuration XML file which is deployed with the application. The type of this class is com.bea.wlevs.configuration.application.DefaultAdapterConfig by default; if, however, you have extended the configuration of the adapter, then the type is whatever have specified in the XSD that describes the extended XML file. For example, in the HelloWorld sample, the type is com.bea.wlevs.adapter.example.helloworld.HelloWorldAdapterConfig.

At run time, Oracle CEP automatically creates an instance of this class, populates it with data from the actual XML file, and passes the instance to the adapter. The adapter methods annotated with the adapter lifecycle annotations can then use the class to get information about the adapter's configuration.

This metadata annotation does not have any attributes.

package com.bea.wlevs.adapter.example.helloworld;
...
import com.bea.wlevs.configuration.Activate;
import com.bea.wlevs.ede.api.RunnableBean;
import com.bea.wlevs.ede.api.StreamSender;
import com.bea.wlevs.ede.api.StreamSource;
import com.bea.wlevs.event.example.helloworld.HelloWorldEvent;

public class HelloWorldAdapter implements RunnableBean, StreamSource {
...
    @Activate
    public void activateAdapter(HelloWorldAdapterConfig adapterConfig) {
        this.message = adapterConfig.getMessage();
    }
...
}

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns="http://www.bea.com/ns/wlevs/example/helloworld"
  xmlns:xs="http://www.w3.org/2001/XMLSchema"
  xmlns:jxb="http://java.sun.com/xml/ns/jaxb" 
  xmlns:xjc="http://java.sun.com/xml/ns/jaxb/xjc"  
  xmlns:wlevs="http://www.bea.com/ns/wlevs/config/application"
  targetNamespace="http://www.bea.com/ns/wlevs/example/helloworld"
  elementFormDefault="unqualified" attributeFormDefault="unqualified" 
  jxb:extensionBindingPrefixes="xjc" jxb:version="1.0">
   <xs:annotation>
      <xs:appinfo>
        <jxb:schemaBindings>
          <jxb:package name="com.bea.wlevs.adapter.example.helloworld"/>
        </jxb:schemaBindings>
      </xs:appinfo>
   </xs:annotation>
   <xs:import namespace="http://www.bea.com/ns/wlevs/config/application" schemaLocation="wlevs_application_config.xsd"/>
   <xs:element name="config">
     <xs:complexType>
       <xs:choice maxOccurs="unbounded">
          <xs:element name="adapter" type="HelloWorldAdapterConfig"/>
          <xs:element name="processor" type="wlevs:DefaultProcessorConfig"/>
          <xs:element name="channel" type="wlevs:DefaultStreamConfig" />
       </xs:choice>
     </xs:complexType>
    </xs:element>
    <xs:complexType name="HelloWorldAdapterConfig">
      <xs:complexContent>
        <xs:extension base="wlevs:AdapterConfig">
          <xs:sequence>
            <xs:element name="message" type="xs:string"/>
          </xs:sequence>
        </xs:extension>
      </xs:complexContent>
    </xs:complexType>
</xs:schema>

<?xml version="1.0" encoding="UTF-8"?>
  <helloworld:config
  ...
    <adapter>
      <name>helloworldAdapter</name>
      <message>HelloWorld - the current time is:</message>
    </adapter>
</helloworld:config>

G.3 com.bea.wlevs.configuration.Prepare

Target: Method

The @Prepare annotation is one of the adapter lifecycle annotations that you use in the Java file that implements your custom adapter to explicitly specify the methods that Oracle CEP uses to send configuration information to the adapter.

Oracle CEP calls the method annotated with @Prepare whenever a component's state has been updated by a particular configuration change.

The method you annotate with this annotation must have the following signature:

public void methodName(AdapterConfigObject adapterConfig)

where methodName refers to the name you give the method and AdapterConfigObject refers to the Java represenation of the adapter's configuration XML file which is deployed with the application. The type of this class is com.bea.wlevs.configuration.application.DefaultAdapterConfig by default; if, however, you have extended the configuration of the adapter, then the type is whatever have specified in the XSD that describes the extended XML file. For example, in the HelloWorld sample, the type is com.bea.wlevs.adapter.example.helloworld.HelloWorldAdapterConfig.

At run time, Oracle CEP automatically creates an instance of this class, populates it with data from the actual XML file, and passes the instance to the adapter. The adapter methods annotated with the adapter lifecycle annotations can then use the class to get information about the adapter's configuration.

This metadata annotation does not have any attributes.

package com.bea.wlevs.adapter.example.helloworld;
...
import com.bea.wlevs.configuration.Prepare;
import com.bea.wlevs.ede.api.RunnableBean;
import com.bea.wlevs.ede.api.StreamSender;
import com.bea.wlevs.ede.api.StreamSource;
import com.bea.wlevs.event.example.helloworld.HelloWorldEvent;

public class HelloWorldAdapter implements RunnableBean, StreamSource {
...
    @Prepare
    public void checkConfiguration(HelloWorldAdapterConfig adapterConfig) {
        if (adapterConfig.getMessage() == null
                || adapterConfig.getMessage().length() == 0) {
            throw new RuntimeException("invalid message: " + message);
        }
    }
...
}

G.4 com.bea.wlevs.configuration.Rollback

Target: Method

The @Rollback annotation is one of the adapter lifecycle annotations that you use in the Java file that implements your custom adapter to explicitly specify the methods that Oracle CEP uses to send configuration information to the adapter.

Oracle CEP calls the method annotated with @Rollback whenever a component whose @Prepare method was called but threw an exception. The server calls the @Rollback method for each component for which this is true.

The method you annotate with this annotation must have the following signature:

public void methodName(AdapterConfigObject adapterConfig)

where methodName refers to the name you give the method and AdapterConfigObject refers to the Java represenation of the adapter's configuration XML file which is deployed with the application. The type of this class is com.bea.wlevs.configuration.application.DefaultAdapterConfig by default; if, however, you have extended the configuration of the adapter, then the type is whatever have specified in the XSD that describes the extended XML file. For example, in the HelloWorld sample, the type is com.bea.wlevs.adapter.example.helloworld.HelloWorldAdapterConfig.

At run time, Oracle CEP automatically creates an instance of this class, populates it with data from the actual XML file, and passes the instance to the adapter. The adapter methods annotated with the adapter lifecycle annotations can then use the class to get information about the adapter's configuration.

This metadata annotation does not have any attributes.

package com.bea.wlevs.adapter.example.helloworld;
...
import com.bea.wlevs.configuration.Rollback;
import com.bea.wlevs.ede.api.RunnableBean;
import com.bea.wlevs.ede.api.StreamSender;
import com.bea.wlevs.ede.api.StreamSource;
import com.bea.wlevs.event.example.helloworld.HelloWorldEvent;

public class HelloWorldAdapter implements RunnableBean, StreamSource {
...
    @Rollback
    public void rejectConfigurationChange(HelloWorldAdapterConfig adapterConfig) {
    }

G.5 com.bea.wlevs.util.Service

Target: Method

Specifies that the annotated method, typically a JavaBean setter method, requires an OSGi service reference.

@Service(filter = "(Name=StockDs)")
public void setDataSourceService(DataSourceService dss) {
    initStockTable(dss.getDataSource());
}