Azure Service Bus Cheat Sheet

• A fully managed message broker service.
• It allows you to decouple applications and services. 
• Provides a reliable and secure platform for asynchronous data and state transfer.
• Enables you to deliver messages to multiple subscribers and fan-out message delivery to downstream systems.

Features

• Message Sessions for implementing first in, first out (FIFO) and request-response patterns to ensure the order of messages in the queue.
• Autoforwarding allows you to remove messages from a queue or subscription and transfer it to a different queue or topic (must be in the same namespace).
• A dead-letter queue holds the messages that can’t be delivered to any receiver.
• It supports a scheduled delivery of messages.
• You can set aside a message using message deferral.
• With client-side batching, you can delay the sending of messages for a certain period of time.

• Autodelete on idle enables you to set an idle interval to automatically delete a queue. Five minutes is the minimum duration.
• Duplicate detection allows you to resend the same message and discard any duplicate copies.
• Batch deletion: Delete multiple messages at once from queues or subscriptions when they expire or are no longer needed.
• Partitioned namespaces (Premium tier): Namespaces can span three availability zones for higher resilience and performance.
• JMS 2.0 support (Premium tier): Fully compliant with Java Message Service 2.0 API for enterprise messaging.
• AMQP 1.0 protocol: Primary wire protocol, enabling interoperability with other AMQP-compliant brokers like ActiveMQ or RabbitMQ.Transaction support: Group multiple operations (send, receive, defer) into an atomic transaction for once-only processing.
• You can continue the operation of your environment in a different region or datacenter with geo-disaster recovery.

Components

• A container for all messaging components is called a namespace.
• You send and receive messages from queues (point-to-point communication).
• Multiple queues and topics are supported in a single namespace, and namespaces often serve as application containers.

• Topics also allow you to send and receive messages and mainly used in publish/subscribe scenarios. It contains multiple independent subscriptions called entities.
• To filter specific messages, you can use rules and filters to define conditions that trigger optional actions.

Security

• Shared Access Signatures (SAS) guards access to Service Bus based on authorization rules.
• You can authenticate and authorize an application to access Service Bus entities such as queues, topics, subscriptions, and filters using Azure AD.
• Create a security identity using Managed identities for Azure resources and associate that identity with access-control roles to grant custom permissions for accessing specific Azure resources.
• Supports AMQP 1.0 and HTTP/REST protocols for secure communication.

Planned Maintenance & Reliability

• During planned maintenance, namespaces are moved to redundant nodes with the latest updates. The move typically completes within 30 seconds.

• Client SDKs automatically disconnect and reconnect. Implement robust retry logic in production applications to ensure transparency.

• Service health alerts: Configure alerts in the Azure portal to receive notifications for planned maintenance or service issues.

• Resource health: Check the Resource Health window in the Azure portal for current status and downtime reasons in the Health History section.

Geo-Replication (Premium Tier)

• Geo-Replication enables data processing to continue operating in a different Azure region during regional downtime.

• Provides enterprise-grade disaster recovery and business continuity.

• Now generally available for Premium tier namespaces.

Pricing

• You are charged based on the following:
  • The number of operations
  • The number of AMQP connections or HTTP calls
• For hybrid connections, you are charged based on the number of listeners.
• With Windows Communication Foundation (WCF) relays, you are charged based on the message volume and relay hours.

Azure Service Bus Cheat Sheet Resources:

https://azure.microsoft.com/en-us/services/service-bus/
https://docs.microsoft.com/en-us/azure/service-bus-messaging/service-bus-messaging-overview