Uploaded byChris Patterson
Event Driven Architecture
The document discusses event-driven architecture (EDA) as a method for building enterprise systems through the flow of events between decoupled components and services. EDA enhances integration by enabling asynchronous operations, minimizing coupling, and fostering fault tolerance, making it suitable for dynamic environments. It differentiates from service-oriented architecture by allowing runtime composition of systems, which leads to greater flexibility and independence of components.
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Event Driven Architecture
- 1. Event Driven Architecture Chris Patterson Senior Architect, RelayHealth chris@phatboyg.com
- 2. Agenda Enterprise Application Integration(EA-eye) Events Event Driven Architecture (ED-eh) .NET sample using MassTransit
- 3. About Me Enterprise SoftwareArchitect Over 20 years of software development experience Over 11 years at a Fortune 15 company Proven track record with distributed, real-time systems
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- 5. Enterprise Application Integration Theprocess of linking applications within a single organization together in order to simplify and automate business processes While avoiding sweeping changes to existing applications
- 6. File Transfer Applications exportand import files Use various formats, requiring translation Often loaded manually, infrequently Affectionately known as ETL or SSIS
- 7. Shared Database The mastermindof the axis of evil Data is tightly coupled to multiple applications Incremental, partial upgrade of application impossible Primary reason for “forklift upgrades”
- 8. Web Services Requires serviceto be available at invocation Results in multiple call stacks, consuming resources Yet another Remote Procedure Call (RPC, COM, CORBA)
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- 11. Messaging Defined data format Asynchronousoperation Minimized coupling Fault tolerance Data Freshness
- 12. Defined Data Format Mutualcontract between producer and consumer Internal formats remain private Integration code remains at the edge of the application, preventing internal changes from impacting the interface
- 13. Asynchronous Operation Processes runin their own execution context Originating process continues Services need not be available at all times
- 14. Minimized Coupling Additive modelreduces change to existing systems Reduces dependencies, increasing service reuse Enables isolated testing of services
- 15. Fault Tolerance Durable messagingimproves recoverability Compensating actions to handle partial failure
- 16. Data Freshness Favors smalldata transfers of related data compared to big files containing unrelated content Minimizes data exchange latency
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- 18. Events Represent a changein state Self-contained Uniquely Identifiable Time relevant, not time sensitive Sourced using messaging
- 19. Unique Identification Enables idempotenthandling of events Improve traceability of related processing Allows correlation with related events
- 20. Self Contained A pureand complete representation of a specific event No references to other data sources No need to time sync to an additional source Reduces dependencies, loosens coupling
- 21. Observable Published events canbe observed by multiple subscribers Event stream processing
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- 23. Execution Events Define theprocess flow Order Coffee Customer placed an order for coffee Present Coffee Coffee handed to customer
- 24. Lifecycle Events Bookends aroundthe process Preparing Coffee Barista began preparing a coffee Coffee Prepared Barista finished preparing a coffee
- 25. Management Events Time periodelapsed, Range or limit exceeded Order Guarantee Exceeded Your order within five minutes, or it’s free Caffeine Junkie Alert Orders of ten or more coffees require approval by FDA
- 26. Business Events Found byobserving the natural order of the business Coffee Order Fulfilled A coffee was ordered, prepared, and delivered Material Shipment Arrived Beans, milk, and cups delivered by brown
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- 28. Event Driven Architecture Amethod of building enterprise systems in which events flow between decoupled components and services A maintainable, sustainable, and extensible model for building complex, distributed applications Well suited for asynchronous, unpredictable environments
- 29. How is itdifferent from SOA?
- 30. How is itdifferent from SOA? Event Driven Architecture complements Service Oriented Architecture
- 31. Service Oriented Architecture Applicationsare composed at design-time Linear flow between services Predictable behavior Request/Response is common, overused
- 32. Event Driven Architecture Applicationsare composed at run-time Asynchronous components Reactive behavior Natural fit for distributed systems
- 33. Autonomous Components Triggered inresponse to an event Independent - no coupling to event producer Self-governing - makes decisions on how to react Self-controlling - responsible for execution context Self-contained - not part of an application
- 34. Event Producers Publish messagesrepresenting an event Often oblivious to the consequences of the generated event
- 35. Event Consumers Subscribe toevents by topic/type/selector Handle events asynchronously No performance penalty for additional consumers
- 37. MassTransit Key Points LightweightService Bus Implementation Loose coupling via publish/subscribe Active Service Pattern Supports MSMQ, ActiveMQ, TIBCO EMS Open Source, Apache 2.0 License
- 38. “Event Driven Architecture is... programmingwithout a call stack.” -Gregor Hohpe, Google
- 39. Testing Individual components testablein isolation Fully unit-testable using mocks and stubs Test-first development helps improve data contract
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- 41. Logging Thorough logging withcorrelation information Adjustable output configurable at runtime
- 42. Visualization Tools Present code-basedlogic in a visual form Aid in identifying composition problems Should be viewable on operational systems
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- 50. Reading Material Enterprise IntegrationPatterns (Hohpe, Woolf) Patterns of Enterprise Application Architecture (Fowler) SOA Patterns (Arnon Rotem-Gal-Oz, Eric Bruno, Udi Dahan)
- 51. Web Sites MassTransit -http://masstransit.googlecode.com/ Topshelf - http://topshelf.googlecode.com/ Magnum - http://magnum.googlecode.com/
- 52. Contact Me Chris@PhatBoyG.com http://blog.PhatBoyG.com http://twitter.com/PhatBoyG http://PhatBoyG.LosTechies.com