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NServiceBus Alt.Net 20100511
- 1. Building enterprise applications with NServiceBus Andreas Öhlund onsdag den 12 maj 2010
- 2. What is adistributed system? “A distributed system is one in which the failure of a computer you didn't even know existed can render your own computer unusable” -Leslie Lamport onsdag den 12 maj 2010
- 3. The first ruleof NServiceBus onsdag den 12 maj 2010
- 4. There is NOService Bus! The first rule of NServiceBus onsdag den 12 maj 2010
- 5. Well, at leastno physical one onsdag den 12 maj 2010
- 6. The second ruleof NServiceBus onsdag den 12 maj 2010
- 7. You DO NOTuse synchronous communication The second rule of NServiceBus onsdag den 12 maj 2010
- 8. The key torobust communication onsdag den 12 maj 2010
- 9. Store and forward onsdagden 12 maj 2010
- 10. Request/Response the NServiceBus way Fire and forget X 2 onsdag den 12 maj 2010
- 11. The effect of tight coupling Temporal Behavioral onsdag den 12 maj 2010
- 12. Communication and coupling onsdagden 12 maj 2010
- 13. Coupling NServiceBus style onsdagden 12 maj 2010
- 14. Command oriented communication CompleteSaleCommand OnlineSales OrderService onsdag den 12 maj 2010
- 15. Sending Messages IBus.Send() bus.Send(new CompleteSaleCommand CreateOrderCommand { ProductId = 123, OnlineSales Quantity = 10 .... }); onsdag den 12 maj 2010
- 16. Receiving and processing of messages public class CompleteSaleMessageHandler: CreateOrderCommand IHandleMessages<CompleteSaleCommand> { OrderService public void Handle(CompleteSaleCommand c) { ... } } onsdag den 12 maj 2010
- 17. Message Contracts • Versioned by the owner • Regular .Net Assembly • Bound to a input queue • class MyMessage : IMessage onsdag den 12 maj 2010
- 18. Throttling the load • Manage traffic peaks • Consumer controls the pace • <MsmqTransportConfig NumberOfWorkerThreads="3" /> onsdag den 12 maj 2010
- 19. What happens whenthe load becomes to heavy for one server? onsdag den 12 maj 2010
- 20. Scaling with theDistributor onsdag den 12 maj 2010
- 21. Building consistent systems • Do we produce predictable results even under failure conditions? • What about non transactional sources? onsdag den 12 maj 2010
- 22. Isolate non transactionalsources as separate endpoints public void Handle(CompleteSaleCommand cmd) { var order = .... orderRepository.Save(order) smtpClient.Send(new MailMessage{...}) } onsdag den 12 maj 2010
- 23. Isolate non transactionalsources as separate endpoints public void Handle(CompleteSaleCommand cmd) { public void Handle(CompleteSaleCommand cmd) { var order = .... orderRepository.Save(order) var order = .... orderRepository.Save(order) bus.Send(new NotifyCustomerRequest { smtpClient.Send(new MailMessage{...}) } EmailAddress = customer.Email, Body = “Order confirmation” }); } onsdag den 12 maj 2010
- 24. Idempotent “Idempotent operations areoperations that can be applied multiple times without changing the result” onsdag den 12 maj 2010
- 25. When things gowrong onsdag den 12 maj 2010
- 26. Messaging gives youa chance to do better • No more showing the users a WSOD • Messages are replayable • Async communication opens up a crucial windows of time for corrections onsdag den 12 maj 2010
- 27. Event oriented communication onsdagden 12 maj 2010
- 28. Publish and subscribe • Everyone get’s a copy • Removes behavioral coupling onsdag den 12 maj 2010
- 29. Billing BillingService OrderAcceptedEvent Shipping SalesService ShippingService Sales Business events onsdag den 12 maj 2010
- 30. Finally a chanceto discuss non functional requirements that business people understand onsdag den 12 maj 2010
- 31. The mechanics ofpub/sub onsdag den 12 maj 2010
- 32. The mechanics ofpub/sub onsdag den 12 maj 2010
- 33. Becoming a subscriber bus.Subcribe<IOrderAcceptedEvent>(); onsdag den 12 maj 2010
- 34. Publishing bus.Publish<IOrderAcceptedEvent>(x=> { ProductId = 123, Quantity = 10 .... }); onsdag den 12 maj 2010
- 35. It’s hard toget it right the first time around onsdag den 12 maj 2010
- 36. Versioning events usinginterfaces public interface IOrderAcceptedEvent2 : IOrderAcceptedEvent { string SomeNewProperty{ get;set; } } onsdag den 12 maj 2010
- 37. Long running transactions onsdag den 12 maj 2010
- 38. Use sagas tomodel long running transactions public class MySaga : Saga<MySagaData>, IAmStartedByMessages<Message1>, IHandleMessages<Message2> { public void Handle(Message1 message) { // code to handle Message1 } public void Handle(Message2 message) { // code to handle Message2 } } onsdag den 12 maj 2010
- 39. Storing state public class MySagaData : IContainSagaData { // the following properties are mandatory public virtual Guid Id { get; set; } public virtual string Originator { get; set; } public virtual string OriginalMessageId { get; set; } } onsdag den 12 maj 2010
- 40. Timeouts public void Handle(Message1 message) { this.Data.SomeID = message.SomeID; RequestTimeout(TimeSpan.FromHours(1), "some state"); } public override void Timeout(object state) { // some business action like: if (!Data.Message2Arrived) ReplyToOriginator(new TiredOfWaitingForMessage2()); } onsdag den 12 maj 2010
- 41. Configuration Developers: use code Administrators: use config files onsdag den 12 maj 2010
- 42. Hosting options • Custom hosting • Website • Smartclient • Commandline • Generic host onsdag den 12 maj 2010
- 43. Using the GenericHost public class EndpointConfig: IConfigureThisEndpoint, AsA_Publisher { } onsdag den 12 maj 2010
- 44. Using profiles toadapt to different environments onsdag den 12 maj 2010
- 45. NServiceBus role in CQRS Style applications onsdag den 12 maj 2010
- 46. NServiceBus is opinionated onsdag den 12 maj 2010
- 47. Why all theseopinions? onsdag den 12 maj 2010
- 48. Don’t use messaging for queries • Queries need to return relatively fast • No benefit from the robustness that NSB gives • Use NSB to cache data close and use native apis to get at that data onsdag den 12 maj 2010
- 49. The end • www.nservicebus.com • www.udidahan.com/blog • andreasohlund.blogspot.com onsdag den 12 maj 2010