detects connections from incoming channels, and manages the connection of the sending channels to the receiving channels. In a TCP/IP network, the listener will "listen" for connections on a specific port. Transmitting data to a queue on another queue manager Queue types: Local queue: represents the location where data is stored awaiting processing. Remote queue: represents a queue on another queue manager. They define the destination queue, which is one element of the routing mechanism for messages. Cluster queue: represents a queue which is reachable via any queue manager in its cluster. A message is placed on a remote queue. The messages goes to a temporary storage transmission queue associated with a channel. On placing a message on a remote queue, the message is transmitted across the remote channel. If the transmission is successful, the message is removed from the transmit queue. On receiving a message, the receiving queue manager examines the message to determine whether the message is for itself or if must go to another queue manager. If the receiving queue manager, the required queue will be checked, and if it exists, the message is placed on this queue. If not, the message is placed on the dead letter queue. MQ has features to manage efficient transmission of data across a variety of communication media. For example, messages can be batched together until a queue reaches a particular depth. Ordering Although the queue is FIFO, it is ordered based on the receipt in the local queue, not the committing of the message from the sender. Messages can be prioritized, and by default, the queue is prioritized in order of arrival. Queues will only be in sequence of addition if the message is added locally. Message grouping can be used to ensure a set of messages are in a specific order, aside from that, if sequence is critical, it is the application's responsibility to place sequence data in the message or implement a handshaking mechanism via a return queue. In reality, ordering will be maintained in straightforward configurations. The log The other element of a queue manager is the log. As a message is placed on a queue or a configuration change is made, the data is also logged. In the event of a failure, the log is used to recreate damaged objects and recreate messages. Only persistent messages are recreated when a failure occurs—"non-persistent" messages are lost. Non-persistent