[EMS-SERVER1] url = tcp://7122, tcp://7124
zone_name = default_mhop_zone
zone_type = mhop
Since we pointed EMS-SERVER1 to routes2.conf, it will look like this:
[EMS-SERVER]
url = tcp://7222, tcp://7224
zone_name = default_mhop_zone
zone_type = mhop
In the diagram above, you see four EMS Server instances with each Fault-Tolerant (FT) pair sharing the same EMS “Server Name”, and you see the client with a complex URL that is constructed such that you have FT pairs separated by a comma and those pairs in a Load-Balanced (LB) arrangement separated by a vertical bar (or pipe symbol).
The second configuration will be accomplished by making a copy of the first and renaming it, prior to making some minor modifications. In the example below, we have named the file tibemsd2.conf
4. Digital certificates are data structures that represent identities. EMS uses certificates to verify the identities of servers and clients. A digital certificate is issued either by a trusted third-party certificate authority, or by a security officer within your enterprise.
5. JMS Java clients can use either JSSE (from Sun JavaSoft) or the SSL implementation from Entrust.
1. JMS clients access the destinations and connection factory objects through interfaces that are portable, so a client application can run with little or no change on more than one implementation of the JMS API.Messaging could be Synchronous, Asynchronous and Reliable types.
Synchronous: A client that waits for the server to respond to a message.
Asynchronous: A client does not have to request server in order to receive message.
Reliable: Can ensure message is delivered safely once and only once.
Circumstances When We can Use JMS :
1. What is the use of exclusive property?
When exclusive is set for the queue, the server sends all the messages on that queue to one consumer. No other consumer can receive messages from the queue.
Instead, these additional consumers act in a standby role; if the primary consumer fails, the server selects one of the standby consumers as the new primary and begins delivering messages to it.
2. Can we set this property to Topics?
3. How to set exclusive property to ems queue?
Set the exclusive property using addprop or setprop in tibemsadmin tool.
EXPLICIT_CLIENT_ACKNOWLEDGE is like CLIENT_ACKNOWLEDGE except it acknowledges only the individual message, rather than all messages received so far on the session.
When EXPLICIT_CLIENT_ACKNOWLEDGE would be used ?
When we receive the messages and put their information in a database and if the database insert operation is slow, you may want to use multiple application threads all doing simultaneous inserts.
As each thread finishes its insert, it can use this mode to acknowledge only the message that it is currently working on.
For EMS message delivery modes Click here.
What is message Compression...?
What is the advantage of Message Compression...?
How to add compression property to message...?
When messages are not stored, compression is not a good option. Why?
JMS Queue Receiver:
Get JMS Queue Message:
MessageProducer:
A MessageProducer object is created by a Session object and is used for sending messages to destinations. For example, using the mySession object created in Session , the following creates a MessageProducer that sends messages to a queue named myQueue:
MessageProducer myQueueSender = mySession.createProducer(myQueue);
Once you have created a MessageProducer, you can use it to send messages. For example, the following sends a message using the queueSender created above:
myQueueSender.send(message);
You can create MessageProducers that do not identify a destination. When the sender or publisher does not specify a destination, you must specify the destination when you send or publish a message as the first parameter of the send() or publish() method.
MessageConsumer:
A MessageConsumer object is created by a Session object and is used for receiving messages sent to destinations. For example, using the mySession object, the following creates a MessageConsumer that retrieves messages from a queue named myQueue:
MessageConsumer myQueueReceiver =
mySession.createConsumer(myQueue);
For queues, messages remain on the queue until they are consumed by a MessageConsumer, the message expiration time has been reached, or the maximum size of the queue is reached.
a) Durable Subscribers for Topics: Only MessageConsumers whose client applications are running receive messages published on a topic. Optionally, Sessions can create durable subscribers to ensure that messages are received, even if the application is not currently running.
(b) Synchronous or Asynchronous Messages: The API allows for synchronous or asynchronous message consumption. For synchronous consumption, the MessageConsumer explicitly calls the receive() method on the topic or queue. For asynchronous consumption, the client registers a MessageListener for the topic or queue. When a message arrives at the destination, the TIBCO Enterprise Message Service server delivers the message by calling the listener’s onMessage() method.
MessageListner:
A MessageListener object acts as an asynchronous event handler for messages. This object implements the MessageListener interface and has one method, onMessage().The onMessage() method is called by the TIBCO Enterprise Message Service server when a message arrives on a destination. You implement the onMessage() method in your MessageListener class to perform the desired actions when a message arrives. Your implementation should handle all exceptions, and it should not throw any exceptions.
Once you create a MessageListener object, you must register it with a specific MessageConsumer. The following creates a queueListener (an implementation of the MessageListener interface) and registers it with the QueueReceiver object:
MessageListener queueListener = new MessageListener();
myQueueReceiver.setMessageListener(queueListener);
You should register the MessageListener with the MessageConsumer before calling the Connection’s start () method to begin receiving messages.
ConnectionFactory:
The ConnectionFactory object encapsulates a set of connection configuration parameters. When a client starts, it typically performs a Java Naming and Directory Interface (JNDI) lookup for the ConnectionFactories that it needs. For example, the following code retrieves the InitialContext using the JNDI properties specified by env, then looks up a ConnectionFactory named myConnectionFactory.
Context ctx = new InitialContext(env);
ConnectionFactory myConnectionFactory =
(ConnectionFactory) ctx.lookup("myConnectionFactory");
Connection:
A Connection object encapsulates a virtual connection with the server.
ConnectionFactory objects create Connection objects. You use a Connection to create one or more Session objects. For example, the following creates a Connection:
Connection myConnection =
myConnectionFactory.createConnection()
When a client application completes, all open connections must be closed. Unused open connections are eventually closed, but they do consume resources that could be used for other applications. Closing a connection also closes any Sessions created by the Connection. To close a connection, use the close() method. For example:
myConnection.close();
Session:
A Session is a single-threaded context for producing or consuming messages. You create MessageProducers or MessageConsumers using Session objects. For example, using the myConnection object created in Connection above, the following creates a Session:
Session mySession =
myConnection.createSession(false, Session.AUTO_ACKNOWLEDGE);
The first parameter to the CreateSession() method determines whether the Session is transactional or not. The second parameter specifies the acknowledge mode of messages received by the session.
The remaining Key Interfaces will be explained in tomorrow's posting.
TIBCO Enterprise Message Service allows you to control access to the server by creating users and assigning passwords, creating groups, setting permissions etc. The server can also authenticate users defined in an external directory (such as an LDAP server)
Permissions for all users and groups must be defined in the access control list for the TIBCO Enterprise Message Service server. There are also administrator permissions that allow administrators to control which actions users can perform on the server such as create destinations, modify users, and view routes. Administrator permissions can apply globally, or they can be granted on specific destinations.
Enabling Access Control
There are two levels where authorization is set.
Server: The authorization property in the main configuration file enables or disables the checking of permissions for all destinations managed by the server. The authorization property also enables or disables verification of user names and passwords.
To enable authorization, edit the tibemsd.conf file:
authorization = enabled
From the command line admin utility:
set server authorization = enabled
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