A Samples

A sample custom stage type and sample function that you can use are provided.

Topics:

• Sample Custom Stage Type

• Sample Custom Function

Sample Custom Stage Type

This sample class defines a custom stage that takes one textual field and produces an MD5 hash for it.

package com.oracle.osacs;

import com.oracle.cep.api.event.*;
import com.oracle.cep.api.annotations.OsaStage;
import com.oracle.cep.api.stage.EventProcessor;
import com.oracle.cep.api.stage.ProcessorContext;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.HashMap;
import java.util.Map;

@SuppressWarnings("serial")
@OsaStage(name = "md5", description = "Create an md5 hex from a string", inputSpec = "input, message:string", outputSpec = "output, message:string, md5:string")
public class CustomMD5Stage implements EventProcessor {

	EventFactory eventFactory;
	EventSpec outputSpec;

	@Override
	public void init(ProcessorContext ctx, Map<String, String> config) {
		eventFactory = ctx.getEventFactory();
		OsaStage meta = CustomMD5Stage.class.getAnnotation(OsaStage.class);
		String spec = meta.outputSpec();
		outputSpec = TupleEventSpec.fromAnnotation(spec);
	}

	@Override
	public void close() {
	}

	@Override
	public Event processEvent(Event event) {
		Attr attr = event.getAttr("message");
		Map<String, Object> values = new HashMap<String, Object>();
		if (!attr.isNull()) {
			String val = (String) attr.getObjectValue();
			String md5 = null;
			try {
				MessageDigest md = MessageDigest.getInstance("MD5");
				md.update(val.getBytes());
				byte[] digest = md.digest();
				md5 = javax.xml.bind.DatatypeConverter.printHexBinary(digest);
			} catch (NoSuchAlgorithmException e) {
				e.printStackTrace();
			}
			values.put("message", val);
			values.put("md5", md5);
		} else {
			values.put("message", "empty");
			values.put("md5", "empty");
		}
		Event outputEvent = eventFactory.createEvent(outputSpec, values, event.getTime());
		return outputEvent;
	}
}

Sample Custom Function

This sample class defines a custom function that takes one textual field and produces an MD5 hash for it.

package com.oracle.osacs;
 
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import com.oracle.cep.api.annotations.OsaFunction;
 
 
public class CustomMD5Function {
               
        @OsaFunction(name = "md5", description = "Create an md5 hex from a string")
        public static String md5(String message) {
               String result = null;
               
               try {
                       MessageDigest md = MessageDigest.getInstance("MD5");
                   md.update(message.getBytes());
                   byte[] digest = md.digest();           
                   result = javax.xml.bind.DatatypeConverter.printHexBinary(digest);     
               } catch (NoSuchAlgorithmException e) {
                       e.printStackTrace();
               }
                                           
             return result;        
        }       
 
}