Serverless Days 2019 - Lost in transaction
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1) The document discusses strategies for managing consistency in serverless architectures, including function coordination, choreography, and orchestration approaches. 2) It notes the challenges of distributed transactions and emphasizes the need for eventual consistency and idempotent functions. 3) Common patterns for coordinating functions are examined, including sagas with compensation handling and workflow/orchestration with a coordinator function.
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Serverless Days 2019 - Lost in transaction
- 1. @berndruecker Lost in transaction? Strategies to manage consistency in serverless architectures
- 2. An example for today – the classical one book hotel book car book flight 1. 2. 3.book trip
- 4. Function collaboration See also e.g. Function Composition in a Serverless World by Timirah James λ Book Car λ Book Hotel λ Book Flight ?
- 5. Merged function λ (Trip) // book har $.post(carHireUrl, ... // book hotel $.post(carHireUrl, ... Car.js Hotel.js Easy to do No overhead Big functions Hard to maintain No independent scaling
- 6. Choreography λ (Car) $.post(carHireUrl, ... invokeHotel() λ (Hotel) $.post(carHireUrl, ... Chaining λ (Car) $.post(carHireUrl, ... carBookedEvent() λ (Hotel) $.post(carHireUrl, ... Event-Chain No extra framework needed Hard to understand the flow Changing the sequence is hard
- 7. Orchestration: Coordinator function λ (Trip) λ (Car) $.post(carHireUrl, ... λ (Hotel) $.post(carHireUrl, ... // book har invokeCar() // book hotel invokeHotel() Functions keep independant Coordinator get‘s long running
- 8. Orchestration: Workflow λ (Trip) // book har startTripWorkflow() λ (Car) $.post(carHireUrl, ... λ (Hotel) $.post(carHireUrl, ... Workflow Engine Car -> Hotel -> ... Functions keep independant No long running function Extra component involved
- 10. Berlin, Germany bernd.ruecker@camunda.com @berndruecker Bernd Ruecker Co-founder and Technologist of Camunda
- 12. Distributed
- 14. You might need to leverage retrying λ (Car) λ (Hotel) Workflow Engine λ (Flight)λ (Trip)
- 15. You might need to leverage stateful retrying λ (Car) λ (Hotel) Workflow Engine λ (Flight)λ (Trip)
- 16. Photo by pixabay, available under Creative Commons CC0 1.0 license.
- 17. Requirement: Idempotency of services! Photo by pixabay, available under Creative Commons CC0 1.0 license.
- 18. Requirement: Idempotency of services! Photo by Chr.Späth, available under Public Domain.
- 19. Make the world a better place. Make your functions idempotent.
- 20. @berndruecker Lost in transaction? Strategies to manage consistency in serverless architectures
- 21. Book Car Book Hotel All or nothing + try { tx.begin(); bookCar(); bookHotel(); tx.commit(); } catch (Exception e) { tx.rollback(); } Once upon a time:
- 23. Pat Helland “ Distributed Systems Guru Worked at Amazon, Microsoft & Salesforce
- 24. Pat Helland Grown-Ups Don’t Use Distributed Transactions “ Distributed Systems Guru Worked at Amazon, Microsoft & Salesforce
- 25. Starbucks does not use two phase commit https://www.enterpriseintegrationpatterns.com/ramblings/18_starbucks.html Photo by John Ingle
- 27. That means Do A Do B Temporarily inconsistent Eventually consistent again t Consistent Local ACID Local ACID 1 function 1 (micro-)service 1 aggregate 1 program 1 resource Violates „I“ of ACID
- 28. Youmightknowthisfrom: Do A Do B Temporarily inconsistent Eventually consistent again t Consistent Photo by Gerhard51, available under Creative Commons CC0 1.0 license.
- 29. we need to embrace eventual consistency
- 31. function
- 32. The classical example Saga book hotel book car book flight cancel hotel cancel car 1. 2. 3. 5.6. In case of failure trigger compensations book trip
- 35. Event-driven choreography Hotel Flight Car Trip Trip failed Trip requested Hotel booked Car booked Request trip Flight failed Car canceled Hotel canceled Perform undo (cancel car booking) Perform undo (cancel hotel)
- 36. The danger is that it's very easy to make nicely decoupled systems with event notification, without realizing that you're losing sight of that larger-scale flow, and thus set yourself up for trouble in future years. https://martinfowler.com/articles/201701-event-driven.html
- 37. The danger is that it's very easy to make nicely decoupled systems with event notification, without realizing that you're losing sight of that larger-scale flow, and thus set yourself up for trouble in future years. https://martinfowler.com/articles/201701-event-driven.html
- 38. The danger is that it's very easy to make nicely decoupled systems with event notification, without realizing that you're losing sight of that larger-scale flow, and thus set yourself up for trouble in future years. https://martinfowler.com/articles/201701-event-driven.html
- 39. Classical example Saga book hotel book car book flight cancel hotel cancel car 1. 2. 3. 5.6. In case of failure trigger compensations book trip
- 40. If your transaction involves 2 to 4 steps, choreography might be a very good fit. However, this approach can rapidly become confusing if you keep adding extra steps in your transaction as it is difficult to track which services listen to which events. Moreover, it also might add a cyclic dependency between services as they have to subscribe to one another’s events. Denis Rosa Couchbase https://blog.couchbase.com/saga-pattern-implement-business-transactions-using-microservices-part/
- 41. Implementing changes in the process Hotel Flight Car Trip Trip failed Trip requested Hotel booked Car booked Request trip Flight failed Car canceled Hotel canceled We have a new basic agreement with the car rental agency and can cancel for free within 1 hour – do that first!
- 42. Implementing changes in the process Hotel Flight Car Trip Trip failed Trip requested Hotel booked Car booked Request trip Flight failed Car canceled Hotel canceled You have to adjust all services and redeploy at the same time! We have a new basic agreement with the car rental agency and can cancel for free within 1 hour – do that first!
- 43. Photo by born1945, available under Creative Commons BY 2.0 license.
- 44. What we wanted Photo by Lijian Zhang, available under Creative Commons SA 2.0 License and Pedobear19 / CC BY-SA 4.0
- 46. Orchestration Hotel Flight Car Trip Trip booked Request trip Book hotel Hotel booked Car booked Flight booked Book car Book flight We have a new basic agreement with the car rental agency and can cancel for free within 1 hour – do that first! You have to adjust one service and redeploy only this one!
- 47. Thoughts on the state machine | workflow engine market
- 48. For today… OSS Workflow or Orchestration Engines Stack Vendors, Pure Play BPMS Low Code Platforms Homegrown frameworks to scratch an itch Integration Frameworks Cloud Offerings Data Pipelines Camunda, Zeebe, … AWS Step Functions, Azure Durable Functions, …
- 50. Describe orchestration with BPMN Trip Trip booked Request trip
- 52. Think of more complicated scenarios… Including stateful retries
- 53. AWS Step Functions Azure Durable Functions Google Cloud Composer Camunda BPM Zeebe Flow Language JSON Source Code Python, acyclic! BPMN BPMN Visualization Simple, proprietary - Simple, proprietary BPMN BPMN Performance & Scale ~ 1k state transitions / sec* ? ? Depends on RDMS Horizontally scalable License and Distribution Cloud Cloud Cloud + OSS (Apache Airflow) OSS + EE, Cloud planned OSS Pricing model 0,025 $ / 1k state transitions Billed as functions $0.074 / vCPU hour web, $0.125 / vCPU hour db, $0.273 per GB storage / month $0.156 / GB trafiic no managed service yet OSS project Please remember that I am biased!
- 55. Clemens Vasters Architect at Microsoft http://vasters.com/archive/Sagas.html
- 56. Clemens Vasters Architect at Microsoft http://vasters.com/archive/Sagas.html
- 57. Clemens Vasters Architect at Microsoft http://vasters.com/archive/Sagas.html
- 58. BPMN Business Process Model and Notation ISO Standard
- 59. Living documentation for long-running behaviour
- 60. Visual HTML reports for test cases
- 61. BizDevOps
- 62. Thoughts on the state machine | workflow engine market
- 63. Does it support stateful operations? Does it support the necessary flow logic? Does it support BizDevOps? How to operate?
- 64. My personal pro-tip for a shortlist ;-) OSS Workflow or Orchestration Engines Stack Vendors, Pure Play BPMS Low Code Platforms Homegrown frameworks to scratch an itch Integration Frameworks Cloud Offerings Data Pipelines Camunda & Zeebe
- 65. Recap • Function coordination might include orchestration and workflow • Carefully decide about choreography vs. orchestration • Grown ups don‘t use distributed transactions but eventual consistency • Idempotency is super important! • Know Saga / Compensation as strategy
- 66. Thank you!