shahidh_k
AWS Community Day
Bangalore
Architecture of scalable and resilient apps with
GraphQL, Amazon RDS and AWS Lambda
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I’m Shahidh

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The Problem
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Traditional architecture
App
Database
API
Payment microservice Restaurant microservice Delivery microservice
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1. Scalable?
2. Resilient?

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Moving towards scale & resilience
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Async architecture
App
Database
API
Event system
Payment processing
Restaurant approval
Delivery assignment
Async microservices
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Serverless
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Serverless 🎉
$ cat index.js
exports.function = (req, res) => {
res.json({"message": "Hello World"});
}
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$ 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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Scalable!
● No OPS
● No VMs to manage
● Don’t need to worry about scaling
● Just write the code
● Deploy
● Scale for “free”
Graphic Source
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Resilient?
● Serverless functions are ephemeral
● No knowledge of state - async
● Trigger them on events
● Add retries to the mix
● We have resiliency
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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
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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
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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
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The cost
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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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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
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However, there’s still one
problem
When stuff happens asynchronously, how do I
get that info back to the app?
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GraphQL
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REST vs GraphQL
Product Brand Category
GET
PUT
POST
PATCH
DELETE
GET
PUT
POST
PATCH
DELETE
GET
PUT
POST
PATCH
DELETE
ProductWithBrand
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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
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GraphQL Subscriptions
Consume async info from the backend without
any worries
It’s as if REST had a WATCH verb
DatastoreApp
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Let’s say I want to build...
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Without GraphQL
● Polling from the client
● Websockets - custom API
● Community fragmentation
● Various patterns in different frameworks
● More work for the developer
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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
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GraphQL Subscriptions
App Datastore
Process
payment
Validate
order
Agent
assignme
nt
Restauran
t approval
New Order
Complete
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However, the cost is...
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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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Traditional
vs
GraphQL + Serverless
Architecture
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Traditional architecture
App
Database
API layer
Payment microservice Restaurant microservice Delivery microservice
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Moving towards scale & resilience
App
Database
API
Event system
Payment processing
Restaurant approval
Delivery assignment
Async microservices
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GraphQL & Serverless architecture
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App
Database
Payment processing
Restaurant approval
Delivery assignment
Mutation/Subscriptions Async serverless functions

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Demo Time!
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Food ordering app
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https://serverless-demo-aws.hasura.app/order-app

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

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

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Thanks
Questions?