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IBM's MQSeries TransactionMessaging SoftwareFollow this link for the official IBM web site for MQSeries.

A brief introduction to MQSeriesWhat constitutes a messageQueue ManagersQueuesChannels

The MQSeries APIMQSeries TechniquesSome example programs using MQSeriesA Java MQSeries Configuration Tool

A brief introduction to MQSeries

As a whole MQSeries enables messages to be exchanged, either synchronouslyor asynchronously, between application programs running on one or moretarget systems. Messages travelling between programs are stored on messagequeues, which are under the control of a service provider called a queuemanager. In general, a queue manager is required on each target system.Messages destined for a different system than the one on which it was created,a remote system, will be communicated to the queue manager on that systemvia an MQSeries channel.

To the programmer MQSeries is presented as an application programminginterface (API) which is unified across the supported hardware and softwareplatforms. The API is very simple and is available in a variety of languagesincluding C, Java and Cobol.

MQSeries can be configured to provide assured delivery of the messages.Assured delivery means that even if the hardware or software platform crashesthe messages within the system will still be delivered, once the platforms arebrought back up.

IBM's MQSeries http://www.fiendish.demon.co.uk/MQSeries/

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On a typical target system MQSeries consists of a queue manager and anumber of queues and channels.

What constitutes a Message

An MQSeries message is simply a collection of data sent by one program andintended for another program. The message consists of control information andapplication specific data. The control information is required in order to routethe message between the programs, and, to some extent, describe thecontents of the application data section. The application data is free-form andMQSeries places no overall constraint on the contents except a maximumlength (4 Mb, or 100 Mb on Version 5). A message can be classed as persistentor non-persistent. A persistent message will survive a software or hardwarecrash / reboot, once communicated to a queue manager, whereas anon-persistent message will not survive. Persistent messages are used as partof the implementation of the assured delivery service supported by MQSeries.

Queue Managers

It is the queue manager that provides the queuing services to the applicationprograms. A queue manager also provides additional functions so thatadministrators can create new queues, alter the properties of existing queuesand control the operation of the queue manager. Many applications can makeuse of the queue manager's facilities at the same time, and they can becompletely unrelated. It is possible to connect queue managers on differentplatforms together, this is achieved via a mechanism called channels.

Queues

Queues are named message repositories upon which messages accumulateuntil they are retrieved by programs that service those queues. Queues residein, and are managed by, a queue manager. Programs access queues via theservices provided by the queue manager. They can open a queue, putmessages on it, get messages from it, and close the queue. It is also possibleto programmatically set, and inquire about, the attributes of queues.

Queues are either defined as local or remote. Local queues allow programs toboth put messages on, and get messages off, while remote queues only allowprograms to put messages on. Remote queues are used in order to provide putaccess to queues that are local to another platform. Any message put onto aremote queue is automatically routed to the associated platform and localqueue by the queue manager via the channels mechanism.

Channels

Channels are named links between platforms across which messages aretransmitted. On the source platform the channel would be defined as a senderand on the destination platform as a receiver. It is the sender channel definitionthat contains the connectivity information, such as the destination platform'sname or IP address. Channels must have the same name on both the source


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