enum PolicyTemplateScope {
	General,Embedded, 
	// Customized: possible to support save certain ad-hoc policy as template
}
 
interface PolicyTemplate {	
	String getName(); // "SINGLE_SOURCE_THRESHOLD_ALERT"
	String getDescription(); // "An alert policy template consuming single stream source."
	String getFormPath(); // "/path/to/form"
 
     <Class extends PolicyTemplateConfig> getConfigType();
	 PolicyTemplateScope getScope();
     PolicyDefinition render(PolicyTemplateConfig);
}
 
abstract class PolicyTemplateConfig {
	internal: String
}
 
final class PolicyTemplateEntity {
	uuid: UUID,
	enabled: Boolean, // FALSE: save, TRUE: deploy
	config: PolicyTemplateConfig,
	template: "org.apache.eagle.policy.PolicyTemplate"
}

// Template Interface and GeneralPolicyTemplateDesc for API
abstract class GeneralPolicyTemplate extends PolicyTemplate{
	final PolicyTemplateScope getScope() {
		return PolicyTemplateScope.General;
	}
}

// Case Example
SingleStreamThresholdPolicyTemplateConfig extend PolicyTemplateConfig {
    from: HDFS_AUDIT_SRC_STREAM,
    partition: {                    
        type: "GROUPBY",field: "USER"
    },
    window: {
        type: "SLIDING_WINDOW",
        configs: {
            length: "20 hour"
        }
    },
    aggregators: [
        {
            function: "SUM",
            field: "USER",
            alias: "USER_COUNT" 
        }
    ],
    filters: [
            {
            field: "USER_COUNT", 
            function: ">",
            value: 20 
        },                  
        {
            field: "USER", 
            function: "NOT IN",
            value: "HADOOP, HDFS, MAPRED"
        }
    ]
}

abstract class EmbeddedPolicyTemplate extends PolicyTemplate{
	final PolicyTemplateScope getScope() {
		return PolicyTemplateScope.Embedded;
	}
}

// Case Example
TOO_LARGE_DELETION_ALERT_CONFIG extend PolicyTemplateConfig {
    users: List<String>,
	hdfsSizeThreshhold: Long
}