Making communication across boundaries simple with Azure Service Bus
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The document provides an overview of Azure Service Bus, detailing its architecture, messaging entities, connectivity options, and exceptions that can arise during operations. It discusses message processing strategies, including receive and delete, peek lock, and the importance of maintaining connections. Additionally, it highlights performance considerations and best practices for implementing reliable message exchanges using Azure Service Bus.
Making communication across boundaries simple with Azure Service Bus
- 1. Yves Goeleven & Sean Feldman Solution Architects & Azure MVPs http://particular.net Azure Service Bus Setting up communication across boundaries
- 2. Introduction to ServiceInsight for NServiceBusAzure Service Bus Secure & reliable communication between software components across network boundaries. • Inside cloud services • Between datacenters • Between branch offices • Hybrid solutions • IoT & Mobile devices When do you need Azure Service Bus ?
- 3. Introduction to ServiceInsight for NServiceBusAzure Service Bus • DNS (mynamespace.servicebus.windows.net): Scale Unit allocation • Load Balancer: High Availability • Gateway Node: Authorization & entity lookup • Broker Node: Servicing entity operations store • Store: SQL Azure Database or Storage Container High Level Architecture Overview Scale Unit Scale Unit DNS L B L B Gateway Gateway Gateway Gateway Client Broker Broker Broker Broker Store Store Store Store Store Store StoreStore Store Store Store
- 4. Introduction to ServiceInsight for NServiceBusAzure Service Bus Entity: a generic term for constructs in an Azure Service Bus namespace Entity ? Queue Subscription Subscription Topic Sending Client Sending Client Receiving Client Receiving Client Receiving Client Receiving Client Each entity is a SQL Azure Database or Storage Blob under the hood! Messaging Entities • Queue • Topic • Subscription • Rule Other (out of scope): Relay, EventHub, Consumer Group, ...
- 5. Connectivity
- 6. Introduction to ServiceInsight for NServiceBusAzure Service Bus 2 Ways to connect • NamespaceManager: to create & manage entities • MessagingFactory: to send/receive Connectivity
- 7. Introduction to ServiceInsight for NServiceBusAzure Service Bus NamespaceManager • Namespace Address • TokenProvider • Methods: • Get, Exists, Create, Update, Delete Connecting to manage entities Namespace Manager Additional options • REST API: https://docs.microsoft.com/en-us/rest/api/servicebus/ • ARM: https://docs.microsoft.com/en-us/azure/service-bus-messaging/service-bus-resource-manager- overview Token Provider REST API HTTPS Creation is really expensive! C#
- 8. Introduction to ServiceInsight for NServiceBusAzure Service Bus Exceptions to deal with: Connectivity • Timeouts • Authorization (manage) Broker Exceptions • Transient • Non-transient Concurrency conflicts What can possibly go wrong? DNS L B Gateway Client Broker timeout timeout Exception Exception Unauthorized Client ? Concurrency conflict timeout C#
- 9. Introduction to ServiceInsight for NServiceBusAzure Service Bus MessagingFactory • Namespace Address • TokenProvider • Connection Settings • Maintains the network connection MessageSender/Receiver • Created by Factory • Logical connection Connecting to send/receive messages Messaging Factory Message Sender Establishing a physical connection is expensive! Message Receiver TCP/WebSocket Connection AMQP/SBMP Messaging Factory Message Sender Message Receiver TCP/WebSocket Connection AMQP/SBMP Broker Gateway Node Broker Gateway Node C#
- 10. Introduction to ServiceInsight for NServiceBusAzure Service Bus You want to receive/send as long as your application lives. Physical connection will drop! Creating a factory every time is not an option: establishing connection is expensive! Lifecycle management • Maintain instances/pools • Manage connection & open new if closed Additional Connectivity Challenges DNS L B Gateway Factory Local interruption Hardware failures Reboot Factory C#
- 12. Introduction to ServiceInsight for NServiceBusAzure Service Bus 2 Ways to receive and process messages • Receive And Delete • Peek Lock Receiving messages
- 13. Introduction to ServiceInsight for NServiceBusAzure Service Bus Message deleted upon receive. Cannot rollback received message. Single shot processing • Exception occurs = message lost! Cloud environment is very susceptible to exceptions! • Advise against this mode for workflow style processing Receive and Delete Message Receiver Receive And Delete Delete C#
- 14. Introduction to ServiceInsight for NServiceBusAzure Service Bus Hide message on receive • Temporal lock • Explicit complete/abandon after processing Multi shot processing • Exception occurs = Retry • Retry counter • Counter exceeded => DLQ Slow processing = retries!!! • RenewLock -> more gotcha’s there, see performance section Peek Lock Message Receiver Peek Lock DLQ Temporal Lock Delete C#
- 15. Introduction to ServiceInsight for NServiceBusAzure Service Bus What Topology to use? • Queue per message type • Queue per receiver Serialization Challenges • Internal serialization or not? • Need to deserialize same way! • What CLR Type (Q per endpoint) Concurrency Challenges • All code must be thread safe Handling Multiple Message Types Receiver Receiver Sender ReceiverSender Is this the right way to construct a message? new BrokeredMessage(“{json}”) Sender Receiver Receiver C#
- 16. Introduction to ServiceInsight for NServiceBusAzure Service Bus MaxDeliveryCount • To avoid locking on processing problematic messages, a message is automatically deadlettered after number of deliveries. Challenges • Poisonous vs errored messages • Building a backing off strategy for retries (3rd party web service) • Monitoring for DLQed messages over multiple entities Dead Letter Queue vs Business Errors DLQ Max Delivery Count failed processing Receiving Client 10 . . . failed processing Receiving Client 2 failed processing Receiving Client 1 C#
- 18. Introduction to ServiceInsight for NServiceBusAzure Service Bus Challenges we’ll cover • Throttling • Message size • Flooding entities • Transactions Sending messages
- 19. Introduction to ServiceInsight for NServiceBusPresentation title Usage exceeding quotas, the broker will throw a ServerBusyException. Mitigation: retry after 10 seconds. Retries can fail as well. Can’t retry the same message object. Exception Handling (User Code) succeeded Sending Client . . . throttled Sending Client throttled Sending Client Operations can and will fail. Based on exception, need to be retried. C#
- 20. Introduction to ServiceInsight for NServiceBusAzure Service Bus Message size (including headers) • Standard tier: 256KB • Premium tier: 1MB Headers: up to 64KB MessageSizeExceededExceptio n Message Size Sending Client Size < MAX Sending Client Size > MAX Warning! Message size is not known until it’s sent out… “To get an accurate value for the size of a BrokeredMessage, you should read the Size property after completing the Send/Receive operation on the BrokeredMessage.”
- 21. Introduction to ServiceInsight for NServiceBusAzure Service Bus Scenario: An orphaned subscription queue receiving messages that are not processed. Challenges • Overflooding subscriptions • Overall namespace performance degradation Overflooding Subscriptions Subscription Subscription Topic Sending Client Receiving Client Receiving Client Solutions • Use Forwarding Gotcha • TTL on subscription Forwarding Receiving Client Sending Client
- 22. Introduction to ServiceInsight for NServiceBusAzure Service Bus All messages succeed or fail – atomic NOT entirely what you think! • Single queue only • No other transactional resources allowed Transactions Queue Sending Client Queue A Sending Client Queue B C#
- 23. Introduction to ServiceInsight for NServiceBusAzure Service Bus All messages succeed or fail - atomic Surprise! A hard limit of 100 messages or TransactionSizeExceededExcep tion Prevents usage of batch completion, has negative performance impact Transactions and Number of Messages Sending Client 1 100… Sending Client 1 100… 101 C#
- 24. Introduction to ServiceInsight for NServiceBusAzure Service Bus All messages succeed or fail – atomic NOT entirely what you think! • Abandon of incoming message can not be included! • Complete can be included • Single queue only • If complete included, sends must go to receive queue • No other transactional resources allowed Transactions with Receive Operations Queue Client Queue A Client Queue B Complete Complete
- 25. Introduction to ServiceInsight for NServiceBusAzure Service Bus A hidden gem in a heap of features Work around for the single queue transaction limit! • Uses receive queue as a transfer queue Use limited within namespace Send Via myQueue Receiving Client queueA Sending Client queueB atomic operation f o r w a r d i n g transfer queue C#
- 26. Performance
- 27. Introduction to ServiceInsight for NServiceBusAzure Service Bus DOs and DONTs • Factories • Batching • Coding practices • Prefetching Performance improvements
- 28. Introduction to ServiceInsight for NServiceBusAzure Service Bus Remember • Using multiple senders helps. • More factories helps more. Multiple Factories Messaging Factory Message Sender Message Sender TCP/Websocket Connection AMQP/SBMP Messaging Factory Message Sender Message Sender TCP/Websocket Connection AMQP/SBMP Broker Gateway Node Broker Gateway Node C#
- 29. Introduction to ServiceInsight for NServiceBusAzure Service Bus 2 Kinds • Batch flush interval • Batched send Batch size • Standard tier: 256KB • Premium tier: 1MB MessageSizeExceededException Bonus! Total message size is not known until it’s sent out… Extra Bonus! Max 100 messages when sending inside transactionscope Batch Sending Sending Client 1 N… Sending Client 1 N… Batch size < MAX Batch size > MAX
- 30. Introduction to ServiceInsight for NServiceBusAzure Service Bus Don’t! Do! Coding Practices That Kill Native Batching foreach(var message in messages) { await sender.SendAsync(message) } var tasks = new List<Task>() foreach(var message in messages) { tasks.Add( sender.SendAsync(message) ) } await Task.WhenAll(tasks)
- 31. Introduction to ServiceInsight for NServiceBusAzure Service Bus How it works • Load additional messages when receiving • Prefetched messages are locked on the gateway • Each client maintains its own in- memory cache of processing Prefetching Messaging Factory Message Receiver Broker Gateway Node C# Gotchas • Cannot renew locks • Prefetch size depends on the processing code speed • Unlocked prefetched messages are not evicted from cache • Prefetched messages with expired TTL are not evicted from cache
- 32. Introduction to ServiceInsight for NServiceBusAzure Service Bus Service Bus is a great service! • With many powerfull features Combining those features while maintaining reliability & performance is the challenge! It’s a balancing act
- 34. Q&A
- 35. Thank you