3.4. JMS MapMessage Types

Qpid supports the Java JMS MapMessage interface, which provides support for maps in messages. The following code shows how to send a MapMessage in Java JMS.

Example 3.5. Sending a Java JMS MapMessage

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.jms.Connection;
import javax.jms.Destination;
import javax.jms.MapMessage;
import javax.jms.MessageProducer;
import javax.jms.Session;

import org.apache.qpid.client.AMQAnyDestination;
import org.apache.qpid.client.AMQConnection;

import edu.emory.mathcs.backport.java.util.Arrays;

// !!! SNIP !!!

MessageProducer producer = session.createProducer(queue);

MapMessage m = session.createMapMessage();
m.setIntProperty("Id", 987654321);
m.setStringProperty("name", "Widget");
m.setDoubleProperty("price", 0.99);

List<String> colors = new ArrayList<String>();
colors.add("red");
colors.add("green");
colors.add("white");        
m.setObject("colours", colors);

Map<String,Double> dimensions = new HashMap<String,Double>();
dimensions.put("length",10.2);
dimensions.put("width",5.1);
dimensions.put("depth",2.0);
m.setObject("dimensions",dimensions);

List<List<Integer>> parts = new ArrayList<List<Integer>>();
parts.add(Arrays.asList(new Integer[] {1,2,5}));
parts.add(Arrays.asList(new Integer[] {8,2,5}));
m.setObject("parts", parts);

Map<String,Object> specs = new HashMap<String,Object>();
specs.put("colours", colors);
specs.put("dimensions", dimensions);
specs.put("parts", parts);
m.setObject("specs",specs);

producer.send(m);
      

The following table shows the datatypes that can be sent in a MapMessage, and the corresponding datatypes that will be received by clients in Python or C++.

Table 3.5. Java Datatypes in Maps

Java Datatype→ Python→ C++
booleanboolbool
shortint | longint16
intint | longint32
longint | longint64
floatfloatfloat
doublefloatdouble
java.lang.Stringunicodestd::string
java.util.UUIDuuidqpid::types::Uuid
java.util.Map[a]dictVariant::Map
java.util.ListlistVariant::List

[a] In Qpid, maps can nest. This goes beyond the functionality required by the JMS specification.