Qpid supports the JMS MapMessage interface, which provides support for maps in messages. The following code shows how to send a MapMessage in JMS.
Example 3.1. Sending a 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 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 3.2. Java Datatypes in Maps
| Java Datatype | Python | C++ |
|---|---|---|
| boolean | bool | bool |
| short | int | long | int16 |
| int | int | long | int32 |
| long | int | long | int64 |
| float | float | float |
| double | float | double |
| java.lang.String | unicode | std::string |
| java.util.UUID | uuid | qpid::types::Uuid |
| java.util.Map[a] | dict | Variant::Map |
| java.util.List | list | Variant::List |
[a] In Qpid, maps can nest. This goes beyond the functionality required by the JMS specification. | ||
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