The JMS APIs in Java

Make QR Code ISO/IEC18004 in Java The JMS APIs

The JMS APIs
QR Code 2d Barcode Creator In Java
Using Barcode printer for Java Control to generate, create QR Code JIS X 0510 image in Java applications.
www.OnBarcode.com
QR Code 2d Barcode Reader In Java
Using Barcode decoder for Java Control to read, scan read, scan image in Java applications.
www.OnBarcode.com
We ve alluded to some examples of JMS code earlier. Now let s get a better understanding of the underlying mechanics.
QR-Code Generation In Java
Using Barcode generator for Java Control to generate, create QR image in Java applications.
www.OnBarcode.com
Making Barcode In Java
Using Barcode printer for Java Control to generate, create Barcode image in Java applications.
www.OnBarcode.com
TopicConnectionFactory and Topic
QR Code JIS X 0510 Creation In Java
Using Barcode drawer for Java Control to generate, create QR Code image in Java applications.
www.OnBarcode.com
2D Barcode Maker In Java
Using Barcode generation for Java Control to generate, create Matrix 2D Barcode image in Java applications.
www.OnBarcode.com
In order to send a JMS message, we need a connection to the JMS provider and a destination address for the message. A JMS connection factory makes the connection to the provider possible, and the destination address is identified by a Topic object. Both the connection factory and the Topic object may be obtained either by using @javax.annotation.Resource to inject these objects directly (into a JEE managed object such as an EJB or Servlet) or by using a manual JNDI lookup.
EAN 13 Creation In Java
Using Barcode creation for Java Control to generate, create EAN13 image in Java applications.
www.OnBarcode.com
Painting Leitcode In Java
Using Barcode generation for Java Control to generate, create Leitcode image in Java applications.
www.OnBarcode.com
@Resource(name="ResourceReferencename") private TopicConnectionFactory connectionFactory; @Resource(mappedName="jndiName") // Non-portable, though some vendors may support private TopicConnectionFactory connectionFactory; public TopicConnectionFactory getConnectionFactory() { return javax.naming.Context.lookup("jndiName"); }
Generating QR Code JIS X 0510 In None
Using Barcode creation for Online Control to generate, create QR Code image in Online applications.
www.OnBarcode.com
Drawing QR Code JIS X 0510 In Visual Studio .NET
Using Barcode generation for ASP.NET Control to generate, create QR Code image in ASP.NET applications.
www.OnBarcode.com
The ConnectionFactory is similar to a DataSource in JDBC. Just as the DataSource provides a JDBC connection to a database, the ConnectionFactory provides a JMS connection to a message router.* The Topic object itself represents a network-independent destination to which the message will be addressed. In JMS, messages aren t sent directly to applications; they re sent to topics or queues. A topic is analogous to an email list or newsgroup. Any application with the proper credentials can receive messages from and send messages to a topic. When a JMS client receives messages from a topic, the client is said to subscribe to that topic. JMS decouples applications by allowing them to send messages to each other through a destination, which serves as a virtual channel. A queue is another type of destination that we ll discuss in detail later.
Barcode Maker In None
Using Barcode printer for Software Control to generate, create Barcode image in Software applications.
www.OnBarcode.com
Decoding EAN13 In C#.NET
Using Barcode recognizer for .NET Control to read, scan read, scan image in .NET framework applications.
www.OnBarcode.com
Connection and Session
Encoding UCC-128 In Visual C#
Using Barcode encoder for .NET framework Control to generate, create GTIN - 128 image in VS .NET applications.
www.OnBarcode.com
EAN / UCC - 13 Maker In Visual C#
Using Barcode creation for VS .NET Control to generate, create EAN 13 image in VS .NET applications.
www.OnBarcode.com
The ConnectionFactory is used to create a Connection, which is an actual connection to the JMS provider:
ECC200 Creator In None
Using Barcode printer for Office Word Control to generate, create Data Matrix ECC200 image in Word applications.
www.OnBarcode.com
Code 128A Encoder In Objective-C
Using Barcode creator for iPad Control to generate, create Code 128 Code Set C image in iPad applications.
www.OnBarcode.com
Connection connect = connectionFactory.createConnection(); Session session = connect.createSession(true,0);
EAN13 Generator In Objective-C
Using Barcode creation for iPhone Control to generate, create EAN 13 image in iPhone applications.
www.OnBarcode.com
Print Barcode In Java
Using Barcode drawer for Eclipse BIRT Control to generate, create Barcode image in BIRT reports applications.
www.OnBarcode.com
Once you have a Connection, you can use it to create a Session. A Session allows you to group the actions of sending and receiving messages. In this case, you need only a single Session. Using multiple Sessions is helpful if you wish to produce and consume messages in different threads. Session objects use a single-threaded model, which prohibits concurrent access to a single Session from multiple threads. The thread that creates a Session is usually the thread that uses that Session s producers and consumers
QR Code Creation In Java
Using Barcode generation for Android Control to generate, create QR image in Android applications.
www.OnBarcode.com
PDF-417 2d Barcode Decoder In None
Using Barcode recognizer for Software Control to read, scan read, scan image in Software applications.
www.OnBarcode.com
* This analogy is not perfect. One might also say that the Session is analogous to the DataSource, since both represent transaction-resource connections.
(i.e., MessageProducer and MessageConsumer objects). If you wish to produce and consume messages using multithreading, you must create a different Session object for each thread. The createSession() method has two parameters:
createSession(boolean transacted, int acknowledgeMode)
The EJB 3.1 specification s Section 13.3.5 stipulates that these arguments are ignored at runtime because the EJB container manages the transaction and acknowledgment mode of any JMS resource obtained from the JNDI ENC. The specification recommends that developers use the arguments true for transacted and 0 for acknowledge Mode, but since they are supposed to be ignored, it should not matter what you use. It s good programming practice to close a Connection after it has been used:
Connection connect = factory.createConnection(); ... // Do work connect.close();
MessageProducer
The Session is used to create a MessageProducer, which sends messages from the caller to the destination specified by the Topic object. Any JMS clients that subscribe to that topic will receive a copy of the message:
MessageProducer producer = session.createProducer(topic); TextMessage textMsg = session.createTextMessage(); textMsg.setText(ticketDescription); producer.send(textMsg);
Message types
In JMS, a message is a Java object with two parts: a header and a message body. The header is composed of delivery information and metadata, and the message body carries the application data, which can take several forms: text, Serializable objects, byte streams, etc. The JMS API defines several message types (TextMessage, MapMessage, ObjectMessage, and others) and provides methods for delivering messages to and receiving from other applications. For example, we can send a new user registration using a MapMessage:
User user = getUser(); // Assume we have this from somewhere ... MessageProducer producer = session.createProducer(topic); MapMessage mapMsg = session.createMapMessage(); mapMsg.setInt("userId", user.getUserId()); mapMsg.setString("firstname", user.getFirstname()); mapMsg.setString("email", user.getEmail()); producer.send(mapMsg);
The attributes of MapMessage ( userId, firstname, and email) can be accessed by name from those JMS clients that receive it. As an alternative, we could use the ObjectMessage type, which would allow us to send the entire User object as the message using Java serialization:
User user = getUser(); // Assume we have this from somewhere ... MessageProducer producer = session.createProducer(topic); ObjectMessage objectMsg = session.createObjectMessage(); ObjectMsg.setObject(user); producer.send(mapMsg);
In addition to TextMessage, MapMessage, and ObjectMessage, JMS provides two other message types: StreamMessage and BytesMessage. StreamMessage can take the contents of an I/O stream as its payload. BytesMessage can take any array of bytes, which it treats as opaque data.
Copyright © OnBarcode.com . All rights reserved.