polyglot heaven
DESCRIPTION
A presentation about data and how to build polyglot applications. The key component, as I see it, to build polyglot data applications is to use an event store as the master data storage and then use other types of databases as views of that data. The presentation also touches on Command Query Responsibility Segragation, CQRS, and event sourcing.TRANSCRIPT
POLYGLOT HEAVEN
How to Build an Async, Reactive Application in 2014
NDC London
Tomas Jansson
04/12/2014
POLYGLOT HEAVEN
How to Build an Async, Reactive Application in 2014
NDC London
Tomas Jansson
04/12/2014
And this should probably be 2015
This here, a title to get accept
THIS IS ME
Tomas Jansson
Manager & Practice Lead .NETBEKK Oslo
@[email protected]/mastojblog.tomasjansson.com
AGENDA
WHY ASYNC AND REACTIVE?
LET’S TALK DATA
WHY POLYGLOT?
WHAT CAN WE DO?
DEMO
SUMMARY
WHY ASYNC AND REACTIVE? - ASYNC
Async doesn’t mean unreliable
Async gives you responsiveness
Data will be consistent
WHY ASYNC AND REACTIVE? - REACTIVE
Message based modular
React on changeEventual
consistent
LET’S TALK DATA
Let’s talk Data
LET’S TALK DATA
Are all data the same?
LET’S TALK DATA
What different kinds of data do we have?
LET’S TALK DATA
Changes, state, relations, cache...
”if all you have is a hammer, everything looks like a nail”
Why polyglot?
WHY POLYGLOT? – CHOOSE THE RIGHT TOOLS
Documents
WHY POLYGLOT? – CHOOSE THE RIGHT TOOLS
DocumentsDocument database
WHY POLYGLOT? – CHOOSE THE RIGHT TOOLS
DocumentsDocument database
Changes
WHY POLYGLOT? – CHOOSE THE RIGHT TOOLS
DocumentsDocument database
Changes Event store
WHY POLYGLOT? – CHOOSE THE RIGHT TOOLS
DocumentsDocument database
Changes Event store
Relations
WHY POLYGLOT? – CHOOSE THE RIGHT TOOLS
DocumentsDocument database
RelationsGraph
database
Changes Event store
What can we do?
Change!
3-LAYERED ARCHITECTURE – WHY OH WHY?
3-LAYERED ARCHITECTURE – WHY OH WHY?
You are mixing your domain
with your query model!
What do you think about ”Divide and Conquer?”
COMMAND QUERY RESPONSIBILITY SEGREGATION - CQRS
CQRS is ”Divide and Conquer” applied on a
architecutral level
CQRS WITH EVENT SOURCING - OVERVIEW
ApplicationCommand Events
Events Projection View
CQRS WITH EVENT SOURCING - OVERVIEW
Application: f(x, ys) ys’, x: Command, ys: list of Events
Projection: f(y, ys) z, y: Event, ys: list of Events, z: View
CQRS WITH EVENT SOURCING - OVERVIEW
Application: f(x, ys) ys’, x: Command, ys: list of Events
Projection: f(y, ys) z, y: Event, ys: list of Events, z: View
Your application is a pure function!
How you implement it is secondary, the events are what
matters!
CQRS WITH EVENT SOURCING - TESTS
[Test]public void PlaceOrder_Should_CreateAnOrder() {
var productId = Guid.NewGuid();var customerId = Guid.NewGuid();var orderId = Guid.NewGuid();var orderItems =
Contracts.Helpers.ToFSharpList(new[] {new OrderItem(productId, 20)});
Given(new ProductCreated(productId, "a name", 20),new CustomerCreated(customerId, "John Doe"));
When(new PlaceOrder(orderId, customerId, orderItems));Then(new OrderPlaced(orderId, customerId, orderItems));
}
Pure functions are easy to test
WHAT WILL I SHOW TODAY?
ApplicationCommand Events
Events Projection View
WHAT WILL I SHOW TODAY?
ApplicationCommand Events
Events Projection View
HTTP
THE KEY COMPONENT
This is where the ”truth” is
stored
Demo!
View databases
Web
Application View
CreateCustomer
CreateProduct
PlaceOrder
GetRecommendations
GetCustomer
GetProduct
SUMMARY
Why async and reactive?
• Responsive
• Scalable
• Modular
SUMMARY
Why async and reactive?
• Responsive
• Scalable
• Modular
Why polyglot?
• Not all data is the same
• Not everything is a nail
SUMMARY
Why async and reactive?
• Responsive
• Scalable
• Modular
Why polyglot?
• Not all data is the same
• Not everything is a nail
Event sourcing and CQRS
• CQRS is divide and conquer on an architecture level
• Your application should be a function
• You don’t have to write in a functional language to write functional code (but it might make it easier)
SUMMARY
Why async and reactive?
• Responsive
• Scalable
• Modular
Why polyglot?
• Not all data is the same
• Not everything is a nail
Event sourcing and CQRS
• CQRS is divide and conquer on an architecture level
• Your application should be a function
• You don’t have to write in a functional language to write functional code (but it might make it easier)
http://www.slideshare.net/mastoj/polyglot-heaven
https://github.com/mastoj/PolyglotHeaven
http://open.bekk.no/polyglot-heaven-a-response-to-the-bekk-radar
Questions?
Thank you!
@TomasJansson