Creating messaging destinations

Messaging destinations are endpoints where messages are sent or received, helping route them between senders and receivers.

About this task

You can create messaging destinations that can be local to a project or shared across other projects. Also, you can also edit and delete messaging destinations using the Actions menu on the Queues and Topics home page.
Note: The maximum capacity limit can be adjusted upon request for a tenant by contacting IBM® support.

Procedure

  1. Go to Events > Messaging
  2. Click Messaging Destinations.
    By default, all the existing queues that are created in the environment are listed.
  3. Do one of the following actions:
    • Click Add Queue to create a new queue.
    • Click Add Topic to create a new topic. By default, the Queues listing page is displayed. Select Topics from the left navigation page to view the topics listing page. All the existing topics that are created in the user tenant are listed.
    The listing page shows the details under Name and Visibility, for example, whether a queue is local or shared and in the Actions columns. You can select a queue or topic from the list to view the metrics.
  4. Enter the following details:
    Name
    Provide the name of the destination.
    Capacity
    Set the maximum number of messages the destination can hold while it waits for subscribers to consume them. If the capacity exceeds the maximum allowed limit for a tenant (the default limit is 10,000), an error message is displayed.
    Shared across all projects
    Select Yes or No to set the destination as local or shared by using this option. The default setting for the Shared across all projects option is No, which means that the queue is project-specific and not accessible in other projects.
  5. Click Save.
    The newly created destination page is displayed along with the details.

Results

After you create a queue or a topic, the metrics available for a queue or a topic are shown when you click the queue or the topic link to view the details.
Name
The name of the queue or the topic.
Capacity
The maximum number of messages the queue or topic can hold while it waits for subscribers to consume the pending messages.
Rates
  • Current Publish Rate - Rate in seconds at which messages are being published to the queue or to the topic.
  • Current Consumption Rate - Rate in seconds at which messages are currently being consumed from the queue or from the topic.
Last Activity
  • Last Published on - The date and time a message was last written to the queue or to the topic.
  • Last Consumed on - The date and time a message was last read from the queue or from the topic.
Messages
  • Published - Number of messages that are published to the queue or topic.
  • Consumed - Number of messages that are consumed from the queue or topic.
  • Pending - Number of messages currently in the queue or topic, waiting to be consumed. When a subscriber is suspended, it stops processing messages, but the instance continues to retain messages intended for it. Over time it can lead to a backlog, which might impact performance and reliability. To manage this backlog, administrators can use the Remove all events option to remove pending messages from suspended subscribers. This action helps reduce message backlog, free system resources, avoid delays in processing new messages, remove outdated data, and make sure of smooth reactivation without overloading the subscriber.
  • Last Message ID - Message ID of the last consumed message.

What to do next

Edit queues
Use the Edit option in the Actions column to edit a specific queue.
Note: Editing a queue results in the deletion of the existing queue and the creation of a new one, which might disrupt subscribers that use the original queue.
Delete queues
Use the Delete option in the Actions column to delete a specific queue.
Note: When a queue is deleted, all the messages in the queue are deleted, and the workflows or flow services become incapable of publishing messages to the queue, potentially disrupting the existing execution.
Edit topics
Use the Edit option in the Actions column to edit a specific topic.
Note: Editing a topic results in the deletion of the existing topic and the creation of a new one, which might disrupt subscribers that use the original topic.
Delete topics
Use the Delete option in the Actions column to delete a specific topic.
Note: If a topic is deleted, all the messages in the topic are deleted, and the workflows or flow services become incapable of publishing messages to the topic, potentially disrupting the existing execution.