Blowing Up the Monolith: Adopting a Modern API Strategy for Hybrid, Multi-Cloud Architectures, Marco Palladino, Co-Founder & CTO, Kong

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Blowing up the monolith

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My name is Marco Palladino
CO-FOUNDER / CTO of Kong
konghq.com
@thekonginc

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This is how most software used to be built

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And this is how we used to scale it

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Growing codebase = Growing pain
Team 1 Team 2 Team 3
Team 4

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Making a change?
Team 4
● The entire system needs to be re-deployed
● They need coordination with other teams
● Higher chances of failure
● Not scalable as the codebase and the team grows

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Monolith vs Microservices
https://martinfowler.com/articles/microservices.html

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Why are Microservices happening now?

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Tooling

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Microservices are replacing local APIs with remote APIs

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A monolith uses primarily function calls.
Order.class
Function createOrder() {
..
// Create Invoice
}
Invoice.class
Function createInvoice() {
..
}
Incoming Request
Api.class
Function request() {
checkAuthentication()
checkRateLimit()
checkParameters()
createOrder()
return result
}
API
Orders Invoice
Monolith
... ...North-South Traffic
“East-West” function call
“East-West” function call
Nobody really calls them this way, but I will
use this terminology to help my narrative
Monolith

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Order.class
Function request() {
checkAuthentication()
checkRateLimit()
checkParameters()
doCreateOrder()
createInvoice()
Return result
}
Invoice.class
Function request() {
checkAuthentication()
checkRateLimit()
checkParameters()
doCreateInvoice()
Return result
}
Network Request
HTTP, gRPC, etc
East-West Traffic
Orders InvoiceIncoming Request
North-South Traffic
Microservices

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Should you blow up the Monolith?

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Microservices are harder, not easier.
Moving to Microservices is slow, not fast.

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Approaching the transition
Clear understanding of
what the Monolith does
and does not
Understanding of
clients that are
consuming the
monolith
Tests, Tests, Tests.

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Strategies
Ice Cream Scoop Lego Strategy Nuclear Strategy

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Build an API and move clients outside
For example: decouple the
frontend from the monolith

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Identify and extract boundaries
How do we handle routing? How do we handle storage and state propagation?

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Database

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Synchronous vs Asynchronous
Microservices and clients
directly consume and invoke
other microservices.
Microservices and clients
push event into an event
collector that’s being
consumed by other
microservices.
Ideal for clients that require an
immediate response or need
to aggregate multiple services
together.
Ideal for
microservice-to-microservice
communication for changing
state without requiring an
immediate response.
Done via HTTP, TCP/UDP,
gRPC,etc.
Done via Kafka, RabbitMQ,
AWS SQS, etc.
Example: Making a request to
retrieve an immediate
response of some sort (ie,
retrieve list of users).
Example: Making a request
that doesn’t require an
immediate response (ie,
“orderCreated” event that
triggers an invoice creation by
another microservice).
Synchronous Asynchronous

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Routing and Versioning
For North-South traffic: For East-West traffic:

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Libraries can help with the transition

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At scale, many moving parts
Orders
Invoice
Orders
Orders
Orders
Orders
Orders
Orders
Orders
Orders
Orders
Invoice
Invoice
Invoice
Invoice
East-West Traffic
Invoice
Invoice
Invoice
Invoice
Service X
Invoice
Invoice
Invoice
Invoice
Service Y
Invoice
Invoice
Invoice
Invoice
Service X
Invoice
Invoice
Invoice
Invoice
Service X

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Service Mesh
Orders
Proxy
Invoices
The speed of each one of these requests
becomes very important in east-west traffic.
Reverse Proxy
The assumption is that the
request Microservice <>
Proxy are basically
instantaneous. Why?
Because they are on
localhost (because sidecar
proxy)

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Observability, routing and error handling are features
shared
by both traditional API Gateways and sidecar proxies

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Common Feature Set
■ Advanced Routing
■ Circuit Breaking and Health-Checks
■ Monitoring and Observability
■ Extensibility
Proxy
Microservice
Proxy
Microservice
Sidecar
Proxy
Client
Proxy
API
Sidecar
ProxyClient Proxy
API
Sidecar
Monolithic
API
In Service Mesh the client is
another microservice inside
the organization.
SERVICE MESH
API GATEWAY / INGRESS
In API GW / Ingress the
client is a third-party entity.
API Request
API Request
API Request
ORG or DEPT EDGE

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The end. But two more things...

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#1 - We are hiring

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