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Lab

Lab exercises

You go through each exercise in three steps: the simulator shows the problem, then the same scenario with the solution, and finally you try the change in your own project with a prompt for a coding agent.

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  1. 01Synchronous startFrontend → Mortgage Calculator API → database
  2. 02Calculator Event SourcingEvents as the source of truth, state = fold(events)
  3. 03Projections and replayRead model from events, fixing a bug by recomputation
  4. 04CQRS: commands and queriesCommand → Write model → Event → Projection (Read model) → Query
  5. 05SnapshotShortening the load of a long stream
  6. 06Optimistic concurrencyTwo advisers, one calculation
  7. 07Event schema evolutionIncomeChanged v1 → v2 and upcasting
  8. 08Calculation V1 → V2 and determinismWhat is a promise to the client and what is a recalculation
  9. 09Application submissionDomain vs. integration events and the broker
  10. 10Risk and approvalRiskAssessmentCompleted/Rejected, MortgageApproved/Rejected, eventual consistency
  11. 11Customer Identity: retry and DLQCustomerIdentityCreationRequested → CustomerIdentityCreated
  12. 12Mortgage Account: duplicates and idempotencyMortgageAccountOpeningRequested → MortgageAccountOpened, Inbox
  13. 13Document Service: delivery orderContractGenerationRequested → ContractGenerated → ContractSigned
  14. 14Disbursement: offline service and backlogMortgageDisbursementRequested → MortgageDisbursed
  15. 15Transactional OutboxWrite and publish are not one transaction (dual write)
  16. 16Saga / Process ManagerThe whole process from approval to disbursement, compensation
  17. 17The whole system under pressureAll failures at once and all defences

Training for your team

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We run the training on your code and your domain problem. We agree the scope, dates and format with you.

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