Microservices and pineapple on pizza what do they have in common - dos and don'ts

@mauroservienti
microservices
and
pineapple on pizza
what do they have in common?
dos and don'ts

@mauroservienti
All I wanna do
when I wake up in
the morning is…
Rosanna, Toto. Toto IV

@mauroservienti
Buy a "Banana Protector"

@mauroservienti
Shopping Cart Microservice
[ list-of ]
- Item ID
- Price
- Quantity
- Inventory
- Name
- Description
Shopping Cart

@mauroservienti
please, welcome the
business

@mauroservienti
Business requirements (#1)

@mauroservienti
Products & Shopping Cart Microservices
[ list-of ]
- Item ID
- Price
- Quantity
- Inventory
- Name
- Description
Shopping Cart
- Item ID
- Price
Products

@mauroservienti
[ list-of ]
- Item ID
- Price
- Quantity
- Inventory
- Name
- Description
Shopping Cart
- Item ID
- Price
Products
copy

@mauroservienti

@mauroservienti
[ list-of ]
- Item ID
- Price
- Quantity
- Inventory
- Name
- Description
Shopping Cart
- Item ID
- Price
- Inventory
Products

@mauroservienti
[ list-of ]
- Item ID
- Price
- Quantity
- Inventory
- Name
- Description
Shopping Cart
- Item ID
- Price
- Inventory
Products
copy
copy

@mauroservienti

@mauroservienti
[ list-of ]
- Item ID
- CurrentPrice
- LastPrice
- Quantity
- Inventory
- Name
- Description
Shopping Cart
- Item ID
- Price
- Inventory
Products

@mauroservienti
[ list-of ]
- Item ID
- CurrentPrice
- LastPrice
- Quantity
- Inventory
- Name
- Description
Shopping Cart
- Item ID
- Price
- Inventory
Products
Is item XYZ in a cart?
Swap & Insert Prices
Move to Saved for…
Update XYZ Price

@mauroservienti
service
boundaries
violation

@mauroservienti
Products Microservices
- Item ID
- Price
- Inventory
Products

@mauroservienti
ownership
is lost

@mauroservienti
Suppliers & Products & Shopping Cart
[ list-of ]
- Item ID
- CurrentPrice
- LastPrice
- Quantity
- Inventory
- Name
- Description
Shopping Cart
- Item ID
- Price
- Inventory
Products
- Supplier ID
- Item ID
- Purchase Price
Suppliers
Update XYZ Price
Are we selling?
New Purchase Price

@mauroservienti
autonomy?
puff, it’s gone

@mauroservienti
HTTP all the rage
because it’s the microservices way

@mauroservienti
“the microservices way”
Shopping CartProducts
Suppliers Update XYZ Price
Are we selling?
New Purchase Price
• Incoming “external” HTTP Post
• HTTP Query from Suppliers to Products
• HTTP Post from Suppliers to Products
• HTTP Query from Products to Shopping Cart
• HTTP Post from Products to Shopping Cart

@mauroservienti
Hops 1 2 3 4 10
Latency 100ms 200ms 300ms 400ms 1 second
“the microservices way”
Does not count any processing time!
…

@mauroservienti
Latency Matters
http://highscalability.com/blog/2009/7/25/latency-is-everywhere-and-it-costs-you-sales-how-to-crush-it.html
Amazon found every 100ms of latency cost
them 1% in sales. Google found an extra .5
seconds in search page generation time
dropped traffic by 20%. A broker could lose $4
million in revenues per millisecond if their
electronic trading platform is 5 milliseconds
behind the competition.
“

@mauroservienti
The snowball effect
[ list-of ]
- Item ID
- CurrentPrice
- LastPrice
- Quantity
- Inventory
- Name
- Description
Shopping Cart
- Item ID
- Price
- Inventory
Products
- Supplier ID
- Item ID
- Purchase Price
Suppliers
Update XYZ Price
Are we selling?
New Purchase Price Ooops...

@mauroservienti
temporal
coupling
anyone?

@mauroservienti
distributed
transactions
over HTTP

@mauroservienti
Messaging
temporal coupling and
distributed transactions

@mauroservienti
The snowball effect
[ list-of ]
- Item ID
- CurrentPrice
- LastPrice
- Quantity
- Inventory
- Name
- Description
Shopping Cart
- Item ID
- Price
- Inventory
Products
- Supplier ID
- Item ID
- Purchase Price
Suppliers
New Purchase Price
+ new price details
Business
Logic
Purchase Price Changed
+ new price details
Business
Logic
Sell Price Changed
MovetoSavedfor…

@mauroservienti
The snowball effect
[ list-of ]
- Item ID
- CurrentPrice
- LastPrice
- Quantity
- Inventory
- Name
- Description
Shopping Cart
+ new price details
Business
Logic
Sell Price Changed
MovetoSavedfor…
Ooops...

@mauroservienti
palliative
alleviates the symptoms

@mauroservienti
Queries are still a thing: Add item to cart.
[ list-of ]
- Item ID
- Price
- Quantity
- Inventory
- Name
- Description
Shopping Cart
- Item ID
- Price
- Inventory
Products
copy price
copy inventory

@mauroservienti
Data sharing is still a thing
[ list-of ]
- Item ID
- CurrentPrice
- LastPrice
- Quantity
- Inventory
- Name
- Description
Shopping Cart
+ new price details
Business
Logic
Sell Price Changed
MovetoSavedfor…

@mauroservienti
We’re flooding the system…
Shopping CartProducts
Update XYZ inventory
Update XYZ Price
Update XYZ Inventory
Over and over, and over, and over…

@mauroservientihttp://montages.no/2009/09/begrepet-grafisk-likhet/

@mauroservienti
User mental model is misleading
[ list-of ]
- Item ID
- CurrentPrice
- LastPrice
- Quantity
- Inventory
- Name
- Description
Shopping Cart
- Item ID
- Price
- Inventory
Products
- Supplier ID
- Item ID
- Purchase Price
Suppliers

@mauroservienti
Let’s focus on the Shopping Cart
[ list-of ]
- Item ID
- CurrentPrice
- LastPrice
- Quantity
- Inventory
- Name
- Description
- Etc…
Shopping Cart

@mauroservienti
Sales shopping cart
[ list-of ]
- Item ID
- Quantity
- Inventory
- Name
- Description
- Delivery Est.
Shopping Cart
- Item ID
- Price
Sales
[ list-of ]
- Item ID
- CurrentPrice
- LastPrice
- Quantity

@mauroservienti
- Item ID
- Price
Sales
[ list-of ]
- Item ID
- CurrentPrice
- LastPrice
- Quantity
Warehouse shopping cart
[ list-of ]
- Item ID
- Quantity
- Name
- Description
- Delivery Est.
Shopping Cart
[ list-of ]
- Cart ID
- Item ID
- Inventory
- Quantity
Warehouse
- Item ID
- Inventory

@mauroservienti
Shipping shopping cart
[ list-of ]
- Item ID
- Quantity
- Name
- Description
Shopping Cart
[ list-of ]
- Cart ID
- Item ID
- Quantity
- Delivery Est.
- Item ID
- Price
Sales
[ list-of ]
- Item ID
- CurrentPrice
- LastPrice
- Quantity
[ list-of ]
- Cart ID
- Item ID
- Inventory
- Quantity
Warehouse
- Item ID
- Inventory
- Item ID
- Delivery
Type
Shipping

@mauroservienti
Marketing tends to be stable
[ list-of ]
- Item ID
- Quantity
Shopping Cart
[ list-of ]
- Cart ID
- Item ID
- Quantity
- Delivery Est.
- Item ID
- Price
- Item ID
- Name
- Description
Marketing
Sales
[ list-of ]
- Item ID
- CurrentPrice
- LastPrice
- Quantity
[ list-of ]
- Cart ID
- Item ID
- Inventory
- Quantity
Warehouse
- Item ID
- Inventory
- Item ID
- Delivery
Type
Shipping

@mauroservienti
Do we need the Shopping Cart at all?
[ list-of ]
- Item ID
- Quantity
Shopping Cart
[ list-of ]
- Cart ID
- Item ID
- Quantity
- Delivery Est.
- Item ID
- Price
- Item ID
- Name
- Description
Marketing
Sales
[ list-of ]
- Item ID
- CurrentPrice
- LastPrice
- Quantity
[ list-of ]
- Cart ID
- Item ID
- Inventory
- Quantity
Warehouse
- Item ID
- Inventory
- Item ID
- Delivery
Type
Shipping

@mauroservienti
Can Sales be responsible for that concept?
[ list-of ]
- Cart ID
- Item ID
- Quantity
- Delivery Est.
- Item ID
- Price
- Item ID
- Name
- Description
Marketing
Sales
Cart ID
[ list-of ]
- Item ID
- CurrentPrice
- LastPrice
- Quantity
[ list-of ]
- Cart ID
- Item ID
- Inventory
- Quantity
Warehouse
- Item ID
- Inventory
- Item ID
- Delivery
Type
Shipping

@mauroservienti
We followed the coupling
[ list-of ]
- Cart ID
- Item ID
- Quantity
- Delivery Est.
- Item ID
- Price
- Item ID
- Name
- Description
Marketing
Sales
Cart ID
[ list-of ]
- Item ID
- CurrentPrice
- LastPrice
- Quantity
[ list-of ]
- Cart ID
- Item ID
- Inventory
- Quantity
Warehouse
- Item ID
- Inventory
- Item ID
- Delivery
Type
Shipping

@mauroservienti
What a (micro)service is not
• A service that has only functionality is a function:
• Like calculation, validation, etc.
• A service that has only data is a database:
• Like [create, read, update, delete] entity
• HTTP/WSDL doesn’t change logical responsibility

@mauroservienti
What a (micro)service is
the technical authority
for a specific business
capability
All business rules (& data) reside within the service

@mauroservienti
Full Vertical Slices
MarketingSales Warehouse Shipping
behavior & databehavior & data behavior & databehavior & data

@mauroservienti
UI & ViewModel
Composition
UI & ViewModel
Composition
UI & ViewModel
Composition
UI & ViewModel
Composition

@mauroservienti
UI & ViewModel
Composition
UI & ViewModel
Composition
UI & ViewModel
Composition
UI & ViewModel
Composition
Dedicated
Technology / FX
Dedicated
Technology / FX
Dedicated
Technology / FX
Dedicated
Technology / FX

@mauroservienti
services need to
communicate

@mauroservienti
• Annoy Notify users of 1 week stale carts
• Wipe 1 month stale carts

@mauroservienti
Services communication channel
ViewModel Composition ViewModel Composition ViewModel CompositionViewModel Composition

@mauroservienti
behavior & data
behavior & data
behavior & databehavior & data
ViewModel Composition
ViewModel Composition ViewModel CompositionViewModel Composition
Add Item to Cart

@mauroservienti
behavior & data
behavior & data
Add Item to Cart
1. Set 1 week timeout

@mauroservienti
behavior & data
behavior & data
Add Item to Cart
2. Set 1 month timeout

@mauroservienti
1 week later
behavior & data
behavior & data
Add Item to Cart
Cart Got Stale

@mauroservienti
1 week later
behavior & data
behavior & data
Add Item to Cart
busCart Got Stale

@mauroservienti
1 week later
behavior & data
behavior & data
Add Item to Cart
bus Cart Got Stale

@mauroservienti
1 week later
behavior & data
behavior & data behavior & data
behavior & data
ViewModel Composition ViewModel Composition
Add Item to Cart
bus
Notify User
Cart Got Stale

@mauroservienti
1 month later
behavior & data
behavior & data
Add Item to Cart
bus
Cart Expired

@mauroservienti
busCart Expired
1 month later
behavior & data
behavior & data
Add Item to Cart
Cart Expired

@mauroservienti
1 month later
behavior & data
behavior & data
Add Item to Cart
busCart Expired Cart Expired

@mauroservienti
1 month later
behavior & data
behavior & data
ViewModel Composition ViewModel Composition ViewModel Composition
Add Item to Cart
bus
Wipe cart Wipe cart
Cart Expired Cart Expired

@mauroservienti
cross services events
can be as thin as
event name and identifiers

@mauroservienti
time tyranny
Demo
bit.ly/aperitech-dos-donts

@mauroservienti
Takeaways
• Boundaries are key to success
• Do not bring in more technology to solve non-
technical problems

@mauroservienti
Takeaways
• Mental model can badly influence design
• Users/Business analysts tend to think in term
of data presentation

@mauroservienti
Takeaways
• Do not name things prematurely
• Premature names stick and drive data
aggregation

@mauroservienti
Takeaways
• Behaviors define how to aggregate data
• Group data that change together and that influence each
other
• Use anti-requirements techniques to validate data
grouping
• Follow the coupling

@mauroservienti
Takeaways
• Behaviors define how to aggregate data
• Use messaging to temporally decouple services

@mauroservienti
you don’t need a distributed system
first rule of distributed systems

@mauroservienti
Mauro Servienti
Solution Architect @ Particular Software
the makers of NServiceBus
mauro.servienti@particular.net
@mauroservienti
//milestone.topics.it

@mauroservienti
microservices
pineapple on
pizza sucks… ;)

Microservices and pineapple on pizza what do they have in common - dos and don'ts

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Microservices and pineapple on pizza what do they have in common - dos and don'ts

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