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*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
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*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
Sample Application
Writing a Basic JMS Application using:
- Synchronous Request/Reply
- Publish/Subscribe
- javax.jms.TopicRequestor class
- JMSReplyTo Header
When this program runs, it reads input from System.in
and then sends the text as a message to the topic
"progress.samples.request".
A "Replier" class should be waiting for the request.
It will reply with a message.
NOTE: You must run the TopicReplier first.
(Otherwise the syncronous request will block forever.)
Usage:
java TopicRequestor -b <broker:port> -u <username> -p <password>
-b broker:port points to your message broker
Default: tcp://localhost:61616
-u username must be unique (but is not checked)
Default: SampleRequestor
-p password password for user (not checked)
Default: password
Suggested demonstration:
- In a console window with the environment set,
start a copy of the Replier. For example:
java TopicReplier -u SampleReplier
- In another console window, start a Requestor.
For example:
java TopicRequestor -u SampleRequestor
- Enter text in the Requestor window then press Enter.
The Replier responds with the message in all uppercase characters.
- Start other Requestors with different user names to see that
replies are not broadcast to all users. For example:
java TopicRequestor -u SampleRequestorToo
- Start other Repliers.
- See that all repliers are receiving all the messages,(as they should).
- See the Requestor only receives one response.
java TopicReplier -u toLower -m lowercase
*/
import org.apache.activemq.*;
public class TopicRequestor
{
private static final String APP_TOPIC = "jms.samples.request";
private static final String DEFAULT_BROKER_NAME = "tcp://localhost:61616";
private static final String DEFAULT_USER_NAME = "SampleRequestor";
private static final String DEFAULT_PASSWORD = "password";
private javax.jms.TopicConnection connect = null;
private javax.jms.TopicSession session = null;
/** Create JMS client for publishing and subscribing to messages. */
private void start ( String broker, String username, String password)
{
// Create a connection.
try
{
javax.jms.TopicConnectionFactory factory;
factory = new ActiveMQConnectionFactory(username, password, broker);
connect = factory.createTopicConnection (username, password);
session = connect.createTopicSession(false,javax.jms.Session.AUTO_ACKNOWLEDGE);
}
catch (javax.jms.JMSException jmse)
{
System.err.println("error: Cannot connect to Broker - " + broker);
jmse.printStackTrace();
System.exit(1);
}
// Create Topic for all requests. TopicRequestor will be created
// as needed.
javax.jms.Topic topic = null;
try
{
topic = session.createTopic (APP_TOPIC);
// Now that all setup is complete, start the Connection
connect.start();
}
catch (javax.jms.JMSException jmse)
{
jmse.printStackTrace();
}
try
{
// Read all standard input and send it as a message.
java.io.BufferedReader stdin =
new java.io.BufferedReader( new java.io.InputStreamReader( System.in ) );
System.out.println ("\nRequestor application:\n"
+ "============================\n"
+ "The application user " + username + " connects to the broker at " + DEFAULT_BROKER_NAME + ".\n"
+ "The application uses a TopicRequestor to on the " + APP_TOPIC + " topic."
+ "The Replier application gets the message, and transforms it."
+ "The Requestor application displays the result.\n\n"
+ "Type some mixed case text, and then press Enter to make a request.\n");
while ( true )
{
String s = stdin.readLine();
if ( s == null )
exit();
else if ( s.length() > 0 )
{
javax.jms.TextMessage msg = session.createTextMessage();
msg.setText( username + ": " + s );
// Instead of publishing, we will use a TopicRequestor.
javax.jms.TopicRequestor requestor = new javax.jms.TopicRequestor(session, topic);
javax.jms.Message response = requestor.request(msg);
// The message should be a TextMessage. Just report it.
javax.jms.TextMessage textMessage = (javax.jms.TextMessage) response;
System.out.println( "[Reply] " + textMessage.getText() );
}
}
}
catch ( java.io.IOException ioe )
{
ioe.printStackTrace();
}
catch ( javax.jms.JMSException jmse )
{
jmse.printStackTrace();
}
}
/** Cleanup resources cleanly and exit. */
private void exit()
{
try
{
connect.close();
}
catch (javax.jms.JMSException jmse)
{
jmse.printStackTrace();
}
System.exit(0);
}
//
// NOTE: the remainder of this sample deals with reading arguments
// and does not utilize any JMS classes or code.
//
/** Main program entry point. */
public static void main(String argv[]) {
// Values to be read from parameters
String broker = DEFAULT_BROKER_NAME;
String username = DEFAULT_USER_NAME;
String password = DEFAULT_PASSWORD;
// Check parameters
for (int i = 0; i < argv.length; i++) {
String arg = argv[i];
if (arg.equals("-b")) {
if (i == argv.length - 1 || argv[i+1].startsWith("-")) {
System.err.println("error: missing broker name:port");
System.exit(1);
}
broker = argv[++i];
continue;
}
if (arg.equals("-u")) {
if (i == argv.length - 1 || argv[i+1].startsWith("-")) {
System.err.println("error: missing user name");
System.exit(1);
}
username = argv[++i];
continue;
}
if (arg.equals("-p")) {
if (i == argv.length - 1 || argv[i+1].startsWith("-")) {
System.err.println("error: missing password");
System.exit(1);
}
password = argv[++i];
continue;
}
if (arg.equals("-h")) {
printUsage();
System.exit(1);
}
// Invalid argument
System.err.println ("error: unexpected argument: "+arg);
printUsage();
System.exit(1);
}
// Start the JMS client for the "chat".
TopicRequestor requestor = new TopicRequestor();
requestor.start (broker, username, password);
}
/** Prints the usage. */
private static void printUsage() {
StringBuffer use = new StringBuffer();
use.append("usage: java Requestor (options) ...\n\n");
use.append("options:\n");
use.append(" -b name:port Specify name:port of broker.\n");
use.append(" Default broker: "+DEFAULT_BROKER_NAME+"\n");
use.append(" -u name Specify unique user name.\n");
use.append(" Default broker: "+DEFAULT_USER_NAME+"\n");
use.append(" -p password Specify password for user.\n");
use.append(" Default password: "+DEFAULT_PASSWORD+"\n");
use.append(" -h This help screen.\n");
System.err.println (use);
}
}