Architecture of scalable and resilient apps with GraphQL & event-driven serverless

Presents an architecture in which asynchronous serverless functions are triggered from an event system listening to database changes, where the functions execute business logic and update the database back with status and a GraphQL server streaming these changes back to client through subscriptions.

Using:
- [Hasura GraphQL Engine](https://github.com/hasura/graphql-engine)
- PostgreSQL on Amazon RDS
- AWS Lambda

Transcript

1. shahidh_k
   AWS Community Day
   Bangalore
   Architecture of scalable and resilient apps with
   GraphQL, Amazon RDS and AWS Lambda
   1
   

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2. shahidh_k 2
   I’m Shahidh
   

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3. shahidh_k
   The Problem
   3
   

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4. shahidh_k
   Traditional architecture
   App
   Database
   API
   Payment microservice Restaurant microservice Delivery microservice
   4
   1. Scalable?
   2. Resilient?
   

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5. shahidh_k
   Moving towards scale & resilience
   5
   

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6. shahidh_k
   Async architecture
   App
   Database
   API
   Event system
   Payment processing
   Restaurant approval
   Delivery assignment
   Async microservices
   6
   

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7. shahidh_k
   Serverless
   7
   

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8. shahidh_k
   Serverless 
   $ cat index.js
   exports.function = (req, res) => {
   res.json({"message": "Hello World"});
   }
   8
   $ serverless functions deploy hello_world --trigger-http
   https://serverless.functions.net/hello_world
   $ curl https://serverless.functions.net/hello_world
   {"message": "Hello World"}
   

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9. shahidh_k
   Scalable!
   ● No OPS
   ● No VMs to manage
   ● Don’t need to worry about scaling
   ● Just write the code
   ● Deploy
   ● Scale for “free”
   Graphic Source
   9
   

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10. shahidh_k
    Resilient?
    ● Serverless functions are ephemeral
    ● No knowledge of state - async
    ● Trigger them on events
    ● Add retries to the mix
    ● We have resiliency
    10
    

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11. shahidh_k
    Example: Food ordering app
    Column | Value
    -------------------+---------------------------------------
    id | a705a43d-c55b-4a8a-ac16-80679bd02404
    created_at | 2018-09-23 13:24:32.159024+00
    user_id | eca786b6-73ae-44c7-b34f-1757af554464
    is_validated | false
    is_paid | false
    is_approved | false
    is_agent_assigned | false
    11
    

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12. shahidh_k
    Order state machine with serverless
    is_validated | false
    is_paid | false
    is_approved | false
    is_agent_assigned | false
    is_validated | true
    is_paid | false
    is_approved | false
    is_agent_assigned | false
    is_validated | true
    is_paid | true
    is_approved | false
    is_agent_assigned | false
    is_validated | true
    is_paid | true
    is_approved | true
    is_agent_assigned | false
    is_validated | true
    is_paid | true
    is_approved | true
    is_agent_assigned | true
    Checks
    payment
    New order
    Validate
    order
    Restaurant
    approval
    Agent
    assignment
    Completed
    12
    

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13. shahidh_k
    Architecture Recap
    ● Microservices became serverless
    functions
    ● Serverless functions are scalable by nature
    ● Database events trigger async serverless
    functions
    ● Resiliency by event source tool instead of
    in the API code
    ● Moved specific failure handling logic to
    generic failure handling
    13
    

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14. shahidh_k
    The cost
    14
    App
    Database
    API
    Event system
    Payment processing
    Restaurant approval
    Delivery assignment
    Generic Event System
    Event system
    Async Serverless Fns
    Payment processing
    Restaurant approval
    Delivery assignment
    

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15. shahidh_k
    High level overview
    Database
    Event system
    Payment
    processing
    Restaurant
    approval
    Delivery
    assignment
    Async serverless
    functions
    A
    Database
    API layer
    Payment
    microservice
    Restaurant
    microservice
    Delivery
    microservice
    Synchronous logic Asynchronous logic
    15
    

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16. shahidh_k
    However, there’s still one
    problem
    

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17. shahidh_k
    GraphQL
    17
    

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18. shahidh_k
    REST vs GraphQL
    Product Brand Category
    GET
    PUT
    POST
    PATCH
    DELETE
    GET
    PUT
    POST
    PATCH
    DELETE
    GET
    PUT
    POST
    PATCH
    DELETE
    ProductWithBrand
    18
    

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19. shahidh_k
    GraphQL changes the way
    we think about UI + API
    ● UI First modelling
    ● Makes API usage more natural
    ● Maps UI components to GraphQL queries
    ● Faster iterations - no back and forth b/n
    frontend-backend
    19
    

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20. shahidh_k
    GraphQL Subscriptions
    Consume async info from the backend without
    any worries
    It’s as if REST had a WATCH verb
    Datastore
    App
    20
    

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21. shahidh_k
    Let’s say I want to build...
    21
    

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22. shahidh_k
    Without GraphQL
    ● Polling from the client
    ● Websockets - custom API
    ● Community fragmentation
    ● Various patterns in different frameworks
    ● More work for the developer
    22
    

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23. shahidh_k
    With GraphQL
    ● Standardised spec
    ● All GraphQL Clients are compatible with all
    GraphQL Servers
    ● Client implementations available for all
    major platforms and frameworks
    ● Subscriptions: access to async info
    ● Less work for the developer
    23
    

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24. shahidh_k
    GraphQL Subscriptions
    App Datastore Process
    payment
    Validate
    order
    Agent
    assignme
    nt
    Restauran
    t approval
    New Order
    Complete
    24
    

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25. shahidh_k
    However, the cost is...
    25
    App
    Database
    API
    Event system
    Payment processing
    Restaurant approval
    Delivery assignment
    Generic Event System
    Event system
    Async Serverless Fns
    Payment processing
    Restaurant approval
    Delivery assignment
    GraphQL Server Subscriptions
    

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26. shahidh_k
    Traditional
    vs
    GraphQL + Serverless
    Architecture
    26
    

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27. shahidh_k
    Traditional architecture
    App
    Database
    API layer
    Payment microservice Restaurant microservice Delivery microservice
    27
    

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28. shahidh_k
    Moving towards scale & resilience
    App
    Database
    API
    Event system
    Payment processing
    Restaurant approval
    Delivery assignment
    Async microservices
    28
    

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29. shahidh_k
    GraphQL & Serverless architecture
    29
    App
    Database
    Payment processing
    Restaurant approval
    Delivery assignment
    Mutation/Subscriptions Async serverless functions
    

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30. shahidh_k
    Demo Time!
    30
    

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31. shahidh_k
    Food ordering app
    31
    https://serverless-demo-aws.hasura.app/order-app
    

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32. shahidh_k
    Food ordering app - scalable
    32
    https://serverless-demo-aws.hasura.app/analytics-app
    

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33. shahidh_k
    Food ordering app - resilient
    33
    https://serverless-demo-aws.hasura.app/console
    

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34. shahidh_k 34
    Thanks
    Questions?
    

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