Annotation Interface MetadataDefinition

Meta annotation for defining new types of event metadata.

In the following example, a transaction event is defined with two user-defined annotations, @Severity and @TransactionId.

 @MetadataDefinition
 @Label("Severity")
 @Description("Value between 0 and 100 that indicates severity. 100 is most severe.")
 @Retention(RetentionPolicy.RUNTIME)
 @Target({ElementType.TYPE})
 public @interface Severity {
     int value() default 50;
 }

 @MetadataDefinition
 @Label("Transaction Id")
 @Relational
 @Retention(RetentionPolicy.RUNTIME)
 @Target({ElementType.FIELD})
 public @interface TransactionId {
 }

 @Severity(80)
 @Label("Transaction Blocked")
 class TransactionBlocked extends Event {
     @TransactionId
     @Label("Transaction")
     long transactionId1;

     @TransactionId
     @Label("Transaction Blocker")
     long transactionId2;
 }
 

Adding @MetadataDefinition to the declaration of @Severity and @TransactionId ensures the information is saved by Flight Recorder.