23 Topic Management

Coherence provides various features and functionalities to help you manage and monitor Topics within a Coherence cluster. MBeans for Topics, Topic Subscribers, and Topic Subscriber Groups are at the core of these capabilities, with three reports available to view the data over time.

Management over REST provides endpoints for accessing and managing all aspects of Topics. The latest versions of the Coherence CLI and Coherence VisualVM Plug-in also support monitoring and management by using the command line and VisualVM, respectively.

Coherence metrics emit Topics, Topic Subscribers, and Topic Subscriber Groups related metrics. Four Grafana dashboards are available to view the Topics metrics over time.

This chapter includes the following topics:

Topic MBeans

When you cofigure Topics, the associated Topics MBeans become available to you.

The Topic MBeans are:

  • PagedTopic MBean - Provides statistics for Topic services running in a cluster.
  • PagedTopicSubscriber MBean - Provides statistics for Topic Subscribers running in a cluster.
  • PagedTopicSubscriberGroup MBean - Provides statistics for Topic Subscriber Groups running in a cluster.

For more information about these MBeans, see the following topics in Managing Oracle Coherence:

Topics Reports

Three reports are available which provide detailed information on Topics, Topic Subscribers, and Topic Subscriber Groups.

The Topics reports are:

  • Topic Report (report-topics.xml) - Provides detailed metrics for Topics defined within a cluster.
  • Topic Subscribers Report (report-subscribers.xml- Provides detailed metrics for Topic Subscribers defined within a cluster.
  • Topic Subscriber Groups Report (report-subscriber-groups.xml) - Provides detailed metrics for Topic Subscriber Groups defined within a cluster

For more information about these reports, see the following topics in Managing Oracle Coherence:

Management Over REST

You are can view and manage Topics, Topic Subscribers, and Topic Subscriber Groups using the Management over REST API.

See REST API for Managing Oracle Coherence.

Managing Topics Using the VisualVM Plug-In and CLI

The Coherence VisualVM Plug-in and Coherence CLI are used to provide management and monitoring of Topics within a Coherence cluster.

See the following resources for more information on each tool:

Grafana Dashboards for Topics

When you enable Coherence metrics, these metrics can be scraped and viewed in four Grafana dashboards.

The Grafana dashboards are:

  • Topics Summary - Shows a summary of all Topics.
  • Topic Details - Shows details about individual Topics.
  • Topic Subscriber Details - Shows details about subscribers.
  • Topic Subscriber Group Details - Shows details about subscriber groups.

These dashboards are available in the Coherence Operator GitHub repository.

For more information about configuring metrics, see Using Oracle Coherence Metrics in Managing Oracle Coherence.

Using Topics with Persistence

Coherence Topics will work with persistence enabled, both active and on-demand. When using on-demand persistence, there are some caveats. If the recover from snapshot functionality is used to recover the state of a topic from persistent storage, the data includes the state associated with subscribers and subscriber groups. If there are active subscribers connected to and subscribing from a topic when a recovery occurs, it can corrupt the subscribers internal state, causing them to fail or to return incorrect data. Recovery from snapshot should only be used when it can be guaranteed that there are no subscribers currently subscribing from topics.

Using Topics with Federation

Coherence Topics cannot be configured to use Federation and hence a topic’s content and meta-data cannot be federated to another Coherence cluster. Federation in Coherence is asynchronous. Therefore, federating a topic would break any delivery and ordering guarantees that a topic provides.