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Event Driven Architecture at NDDNUG
The document discusses event driven architecture and how it compares to service oriented architecture. It defines key concepts in event driven architecture like events, commands, autonomous components, event producers and consumers. It also provides an example of how the .NET library MassTransit implements concepts like loose coupling and publish/subscribe using messages and events.
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Event Driven Architecture at NDDNUG
- 1. EVENT DRIVEN ARCHITECTURE Chris Patterson Senior Architect, RelayHealth Chris@PhatBoyG.com
- 2. Agenda Review Enterprise ApplicationIntegration Introduce Event Driven Architecture Define Events .NET sample using MassTransit
- 3. About Me Enterprise SoftwareArchitect 20+ years in commercial software development 12+ years at a Fortune 15 company Proven history with distributed, real-time systems 2009 - Awarded Microsoft Visual C# MVP
- 4. ENTERPRISE APPLICATION INTEGRATION
- 5. ENTERPRISE APPLICATION INTEGRATION Linking applications in an organization together to simplify and automate business processes
- 6. Shared Database Multiple applicationscoupled to single schema Unclear ownership of schema Blurred application boundaries Linked servers (SQL to SQL RPC) Changes often affect multiple applications
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- 8. File Transfer Extract -Transform - Load (ETL)
- 9. File Transfer Extract -Transform - Load (ETL) Asynchronous
- 10. File Transfer Extract -Transform - Load (ETL) Asynchronous Simple interoperability through common formats
- 11. File Transfer Extract -Transform - Load (ETL) Asynchronous Simple interoperability through common formats Timeliness of data can lead to inconsistencies
- 12. File Transfer Extract -Transform - Load (ETL) Asynchronous Simple interoperability through common formats Timeliness of data can lead to inconsistencies Large data volume containing unrelated data
- 13. File Transfer Extract -Transform - Load (ETL) Asynchronous Simple interoperability through common formats Timeliness of data can lead to inconsistencies Large data volume containing unrelated data Ownership of files, cleanup, versioning
- 14. Web Services Explicit Contract(WSDL, DataContract) Synchronous Operation leads to sequencing Services must be available at invocation Nested call stacks fragile, consume resources Remote Procedure Call (RPC, COM, CORBA) The network is unreliable
- 15. RPC Exchange Prepare Call Return Process
- 16. RPC Exchange Prepare Call Return Process
- 17. RPC Exchange e bl ia Prepare Call el nr U re As rk Return Process wo et N
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- 19. Message Exchange Create Process Send Receive
- 20. A-Synchronicity Message producers arenon-blocking Fire and forget Message consumers run in their own process Introduces a more complex programming model
- 21. Minimized Coupling Eliminates temporalcoupling Enables isolated testing of services Reduces dependencies, increasing service reuse
- 22. Explicit Contract Agreement betweenproducer and consumer Internal data structure remains private Integration points remain at the application’s edge Eliminates propagation of internal changes
- 23. Fault Tolerance Messages improverecoverability Durable message transports
- 24. Data Availability Enables small,frequent transfers of related content Distribute system load over a wider time window
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- 26. EVENT DRIVEN ARCHITECTURE A method of building enterprise systems in which events flow between decoupled components and services
- 27. Another Architecture? Service Oriented Event Driven Architecture Architecture
- 28. Service Oriented Event Driven Architecture Architecture Complimentary
- 29. Service Oriented Event Driven Architecture Architecture Complimentary
- 30. SOA 1.0 Applications arecomposed using a designer Synchronous programming model Step-by-step (F10) flow through services Majority of interactions are request/response
- 31. Event Driven Architecture Componentsare assembled at run-time Asynchronous programming model Reactive behavior Leverages one way, fire and forget, messaging
- 32. Autonomous Components Defined byresponsibility Independent Self-governing - makes decisions on how to react Self-controlling - responsible for execution context Self-contained - not part of an application
- 33. Event Producers Publish events Obliviousto consumer reactions Unaffected by high number of consumers
- 34. Event Consumers React toevents Subscribe by topic/type/selector Asynchronous operation
- 35. Business Components Logical groupingof autonomous components Represent a complete business process
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- 37. Commands Tell a componentor service to do something Initiated by an event, interaction, etc. Use correlation for tracing, idempotence Sent using messaging (not published)
- 38. Reset Password User initiatesa password reset Password service sends reset email User clicks link in email
- 39. Message Body public classResetPassword { public Guid RequestId { get; set; } public string Username { get; set; } }
- 40. Compared To... public voidResetPassword(string username) public class ResetPassword { public Guid RequestId { get; set; } public string Username { get; set; } }
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- 42. Pablo’s Fiesta! February 26, 27, 28 Austin, TX Open Spaces fiesta.lostechies.com
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- 44. EVENTS Represent a changein state
- 45. Self Contained A pureand complete representation of a specific event Time relevant, not time sensitive Avoid references to internal data Reduces dependencies, loosens coupling
- 46. Identified Each event shouldhave its own unique identifier
- 47. Related Related events shouldshare a common identifier Allows event tracing (the new F11) Assists in combining events into processes
- 48. Observed Events are publishedas messages Multiple components can subscribe to the same event
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- 50. Business Events Map toreal world events that occur in business Item Added to Cart Invoice Received Order Shipped Payment Requested
- 51. Lifecycle Events Notifications relatedto the life of a state or process Preparing Shipment / Shipment Prepared Authorizing Payment / Payment Authorization Complete Session Started / Session Completed
- 52. Management Events Relate eventsto time, ranges, limits Timely Service Guarantee Exceeded Your order within five minutes, or it’s free Popular Item Notification Items with a 5x increase in sales in an hour
- 54. MassTransit Key Points LightweightService Bus Implementation Loose coupling via publish/subscribe Active Service Pattern Supports MSMQ, RabbitMQ, ActiveMQ, TIBCO EMS Open Source, Apache 2.0 License
- 55. “EVENT DRIVEN ARCHITECTURE IS... programmingwithout a call stack.” -Gregor Hohpe, Google
- 56. Testing Individual components testablein isolation Fully unit-testable using mocks and stubs Test-first development helps improve data contract
- 57. Logging Thorough logging withcorrelation information Log level configurable at runtime
- 58. Visualization Tools Present code-basedlogic in a visual form Aid in identifying composition problems Should be viewable on operational systems
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- 71. CONTACT ME Chris@PhatBoyG.com http://PhatBoyG.LosTechies.com twitter: @PhatBoyG voice: text “cmp” to 50500