Service Bus Topic Subscription

Overview

Azure Service Bus is a cloud messaging service that connects applications, devices, or services running in the cloud to one another. Topics and Subscriptions provide a one-to-many publish/subscribe pattern; in contrast to queues, where a single consumer processes each message, they are useful for scaling to large numbers of recipients.

Business value

Managing Service Bus Topic Subscription messages from Turbo360 gives you visibility the Azure portal lacks, letting you query, filter, and recover dead-lettered messages directly, reducing the time to detect and resolve subscription-level message failures.

How it works

• Once a Service Bus Topic Subscription is associated with a Business Application, you can query messages in the Active-end or Dead-Letter queue, in Peek or Deferred state, filter them by system or custom properties, and process them, all from Turbo360 instead of switching to Azure tools.
• Peek mode retrieves messages without affecting active receivers and without increasing delivery count or enabling delete; Defer mode affects active receivers, increases delivery count, and allows delete. Deferred messages are accessible from the Deferred Active Messages and Deferred Dead-Letter tabs without needing to know their sequence number.
• The Actions options (Save, Resubmit, Repair & Resubmit) are disabled for messages over 1 MB, and messages over 10 MB lose access to context menu options other than Resubmit and Properties.

Permissions

Access to Service Bus Topic Subscription actions is controlled through RBAC when adding a role to a Business Application.

Purge is split into two separately grantable permissions, so you can allow a custom role to purge only active messages, only dead-letter messages, both, or neither. Consider the following when you grant them:

• To use Messaging > Purge, a role needs Manage on Automated Task and at least one of the two purge permissions.
• In the Purge messages blade, the Active messages and Dead-letter messages options are enabled based on the role's permissions. The option the role isn't allowed to use is disabled.
• In the Process Service Bus dead-letter automated task, the Delete and Resubmit & Delete operations require Purge dead-letter messages. Resubmit & Delete also requires Reprocess.
• If an existing custom role should purge dead-letter messages, open the role and check that Purge dead-letter messages is selected for the resource. A role that has only Purge active messages can't purge dead-letter messages.
• Users with the Owner or Contributor role on the Business Application aren't limited by these checkboxes.

Operations

Turbo360 lets you query, filter, and process Service Bus Topic Subscription messages directly, without switching to the Azure portal.

View and filter messages

• Retrieve messages: query messages in Active-end or Dead-Letter queues, in Peek or Deferred state, by message count and sequence number. Use this when you need visibility into subscription messages that the Azure portal doesn't surface.

• Filter messages: query retrieved messages by system or custom properties, dead-letter reason, or Enqueued time using AND/OR operators.

• Save a query filter: save a filter using the Save button next to Filter, and access it later from Saved queries. A default query can also be defined to pre-populate the Filter option.

Update status

Change the status of the Topic Subscription by selecting from the available options. Use this when you need to enable or disable the subscription without going to the Azure portal.

Bulk operations

• Bulk status update: update the status of multiple Topic Subscriptions at once from the resource section.

• Bulk Repair & Resubmit: repair and resubmit multiple selected messages via Actions -> Repair & Resubmit.

Rules management

• Manage filters: add filters under Manage -> Filters to control which messages from the Topic reach the Subscription. Use this when only a subset of Topic messages should be delivered to a given Subscription.
  • SQL Filter: a SQL-like conditional expression checked against user-defined and system properties of incoming messages.
  • Correlation Filter: a list of conditions checked against one or more user and system properties of an incoming message.

For example, to receive only messages with BookingId between 1 and 100 and set customer to Known:

Filter: BookingId >= 1 and BookingId <= 100
Action: SET Customer = 'Known'

Process messages

Turbo360 supports Resubmit, Repair & Resubmit, Save, Delete, Backup, viewing message details/properties/dead-letter reason, and automated tasks for processing messages.

• Resubmit: resubmit a single message or a bulk selection from active-end or dead-letter back to the same topic, a different topic, a queue, or an API endpoint.

• Repair and Resubmit: repair a message inline or in bulk via Excel sheet before resubmitting.

• Save messages: download selected messages as a compressed (zipped) folder via Actions -> Save.

• Backup and Delete: delete messages from active-end or dead-letter, optionally backing them up to an associated Storage Blob Container first.

Inline task to purge messages

• Inline task: quickly purge messages from the subscription by specifying message count, queue type (Active-end or Dead-Letter), and Enqueued At time. You can purge only the message state your role allows: Purge active messages enables Active messages, and Purge dead-letter messages enables Dead-letter messages.

Task status can be viewed under Automated tasks > Task history.

The Automated tasks feature schedules active and dead-lettered messages to be processed to a Queue or Topic; this is useful when multiple Topic Subscriptions need different schedules.

Monitoring

Service Bus Topic Subscription supports property and status monitoring rules, configured under Service Bus Topic Subscription > Monitoring.

Property and status monitoring

Tracks the properties and current status of the Topic Subscription. Use this when you need to be alerted if a configured property or status crosses the desired threshold.

1. Navigate to Service Bus Topic Subscription > Monitoring.
2. Configure the properties and current status with the desired threshold.
3. Click Save.

Troubleshooting

1. Repair & Resubmit or Save options are disabled for a selected message
   Cause: The selected message exceeds 1 MB, or for messages over 10 MB, an unsupported context menu option was attempted.
   Fix: Use Resubmit or Properties for messages over 10 MB; for 1–10 MB messages, only Resubmit-class actions remain available.
2. A resubmitted message appears as a duplicate
   Cause: Duplicate detection is enabled on the destination and the resubmitted message reused the original message ID.
   Fix: Regenerate the message ID manually or automatically before resubmitting.
3. Filter does not route expected messages into the Subscription
   Cause: The SQL or Correlation filter under Manage -> Filters doesn't match the incoming message properties.
   Fix: Review the filter condition and the message's system and custom properties, then adjust the filter.
4. Deferred messages cannot be found
   Cause: The Deferred Active Messages or Deferred Dead-Letter tab was not checked, or the sequence number was used to search instead of relying on Turbo360's deferred access.
   Fix: Use the Deferred Active Messages or Deferred Dead-Letter tabs directly rather than searching by sequence number.
5. A custom role can't purge dead-letter messages
   Cause: The role has Purge active messages but not Purge dead-letter messages. The Dead-letter messages option is disabled in the Purge messages blade, and Delete is disabled in the Process Service Bus dead-letter task.
   Fix: Edit the role and select Purge dead-letter messages for the Service Bus Topic Subscription resource.

FAQs

1. Can I give a role permission to purge only dead-letter messages?
   Yes. Select Purge dead-letter messages and leave Purge active messages cleared. The role also needs Manage on Automated Task to use Messaging > Purge.

2. How do I let a custom role purge both active and dead-letter messages?
   Select both Purge active messages and Purge dead-letter messages for the resource. A role that has only one of them can purge only that message state.

3. Does the separate purge permission apply to other resource types?
   The two permissions apply to Service Bus Queue and Service Bus Topic Subscription. Other resource types that support purge keep a single Purge permission.

Related articles

• Service Bus Queue
• Service Bus Topic
• Rules configuration