Revisiting WMQ Basics - Queues & Channels
I was informed of an assignment related to WebSphere MQ troubleshooting and performance enhancement but had to turn it down as I have been off MQ for quite sometime. However, I've decided now that I will refresh my MQ skills and become hands-on. I am starting from the basics and will post interesting/important notes here as I go along. I may choose to skip topics that seem a bit too obvious to me.
Queues
WebSphere MQ has four types of queues: Local, Remote, Alias and Model queue. The first 3 function as their names' suggest, the last one - Model queue is a template that can be used to define new queues with the same properties.
Triggering
Triggering happens when a message appears on an Initiation queue. The process defined and associated with the trigger is started when a message with the matching trigger critieria occurs on the queue.
Message Channels
Message Channels communicate between Queue Managers and can transmit messages in one direction only.
A transmission queue (XMITQ), which is a local queue is mentioned in the channel definition to associate it with the channel.
Types of Channels
Channels are initiated through programs called Message Channel Agents (MCA). Persistent messaging is handled by MCAs as they are the ones who deliver the messages. The message is not removed from the xmit queue (transmission queue) until the MCA confirms the placement on the target queue.
I will next take a look at the properties of MQ messages.
Queues
WebSphere MQ has four types of queues: Local, Remote, Alias and Model queue. The first 3 function as their names' suggest, the last one - Model queue is a template that can be used to define new queues with the same properties.
Triggering
Triggering happens when a message appears on an Initiation queue. The process defined and associated with the trigger is started when a message with the matching trigger critieria occurs on the queue.
Message Channels
Message Channels communicate between Queue Managers and can transmit messages in one direction only.
A transmission queue (XMITQ), which is a local queue is mentioned in the channel definition to associate it with the channel.
Types of Channels
- Sender: Sends message and initiates connection to Receiver
- Receiver: Waits for initiation from Sender
- Cluster-Sender: Used in Cluster Queue Managers (need to find out more)
- Cluster-Receiver: Used in Cluster Queue Managers (need to find out more)
- Requester: Sends request and becomes receiver
- Server: Accepts request to start from requester, then becomes sender
Channels are initiated through programs called Message Channel Agents (MCA). Persistent messaging is handled by MCAs as they are the ones who deliver the messages. The message is not removed from the xmit queue (transmission queue) until the MCA confirms the placement on the target queue.I will next take a look at the properties of MQ messages.
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