let's not rewrite it all

LET’S NOT REWRITE IT ALLMICHELLE BRUSH

I’M TIRED OF BUILDING METAPHORS.

BUT I’M GOING TO USE ONE…

VIVALAS VEGAS!

TEXTDidier B, CC 2004https://commons.wikimedia.org/wiki/File:Boardwalk-Casino.jpg

https://commons.wikimedia.org/wiki/File:Boardwalk-Casino.jpg

1200 BRAND NEW ENGINEERS

HOME OF THE VDARA HOTEL

DEATH RAY

$1.84 million

free

- OR -

$9.2 Billion

EVOLUTIONARY ARCHITECTURE

OR TWO…

"Almost no buildings adapt well. They're designed not to adapt..."

"When we deal with buildings we deal with

decisions taken long ago for remote reasons."

"In wider use, the term architecture always means 'unchanging deep structure'“

How Buildings Learn

PURPOSE, NOT MODERNIZATION, DRIVES CHANGE

SHEARING LAYERS OF CHANGE TYPES OF REWRITES

LANGUAGE

ARCHITECTURE USER INTERFACE

DESIGNAPI/FRAMEWORK

CODE

PARADIGM…

REFACTOR BAD CODE, DON’T REWRITE IT

RULE 0:

for(int i = 0; i < count1; ++i) { for(int j = 0; j < count2; ++j) { for(int k = 0; k < count3; ++k) { for(int l = 0; l < count4; ++l) { for(int m = 0; m < count5; ++m) { for(int n = 0; n < count6; ++n) { for(int o = 0; o < count7; ++o) { for(int p = 0; p < count8; ++p) { for(int q = 0; q < count9; ++q) { for(int r = 0; r < count10; ++r) { for(int s = 0; s < count 11 for(int t = 0; t < count for(int u = 0; for(int v = 0 for(int w for(i fo

FOR-NADO?

LANGUAGE


DESIGNAPI/FRAMEWORK

CODE


DESIGNAPI/FRAMEWORK

CODE

LANGUAGE


DESIGNAPI/FRAMEWORK

CODE

VIRTUAL MACHINE

HOW TO MIGRATE SOFTWARE

HOW SOFTWARE LEARNS

MINIMIZE THE SCOPERULE 1:

?

core business logic

core business logic

core business logic

WHAT WERE WE REALLY TRYING TO DO?

GET RID OF THIS

DEFINE AND STICK TO A SMALL SET OF OBJECTIVES.

COROLLARY 1.1:

EXAMPLE OBJECTIVES

Improve the time it takes for data to be available in applications.

EXAMPLE OBJECTIVES


Increase resiliency of pipeline to system failures.

EXAMPLE OBJECTIVES



Reduce overall memory utilization of core algorithms.

EXAMPLE OBJECTIVES




Increase responsiveness of application during key workflows.

EXAMPLE OBJECTIVES





Reduce time to implement new workflows.

EXAMPLE OBJECTIVES





Reduce time to implement new workflows.

Eliminate unsupported or unmanageable technical dependencies.

EXAMPLE OBJECTIVES

CREATE A TECHNICAL VISIONRULE 2:

THE POWER OF HEURISTICS


BREADTH-FIRST SEARCH



DJIKSTRA’S ALGORITHM



DJIKSTRA’S ALGORITHM

A*

MAKE EVERYONE UNDERSTANDS IT.

COROLLARY 2.1:

We will never cross the streams.

We monitor everything.

Assume nothing about connectivity.

ENFORCE IT.

COROLLARY 2.2:




REDUCE COMPLEXITYRULE 3:

LOOK FOR OPPORTUNITIES TO ELIMINATE WASTE.

150

130 components

75 essential

LOOK FOR OPPORTUNITIES TO ELIMINATE WASTE.

150

130 components

75 essential

black list

WORK IN THIN SLICESRULE 4:

UNBOUNDED QUEUE OF CHANGE REQUESTS


“THE REWRITE”

“THE REWRITE”

3 YEAR REWRITE COST 7 YEARS OF FEATURE DEVELOPMENT


“THE REWRITE”


“THE REWRITE”

MIGRATION

MIGRATION

MIGRATION

WHAT IS MOST LIKELY TO CHANGE?

SLICES

SLICESSupports continued development of unaffected layers.

Minimizes opportunities for cross-layer improvements.

SLICESAligns with functional

understanding of the system.

Allows testing of full stack assumptions more quickly.

SLICESDATA SETS

SLICES

IDENTIFY PATTERNS

& RISKS.

RAPIDLY MIGRATE LAYERS.

EACH COMPONENT IS STYLED

CONSISTENTLY.

PLAN TO BUILD ADAPTERS & ABSTRACTIONS

COROLLARY 3.1:

ACCEPT YOU MAY HAVE TO WRITE THROWAWAY CODE

COROLLARY 3.2:

SLICES

PURPOSE, NOT MODERNIZATION, DRIVES

CHANGE

BUILD YOUR TESTS FIRSTRULE 5:

WHAT’S YOUR BETTER THAN NOTHING?

pieces that are constantly changing

BOUNDARY THAT IS FIXED AND UNCHANGING

(for each slice)



(for each slice)

INPU

T

OUTP

UT



(for each slice)

INPU

T

OUTP

UTTESTS

shortest pathfinding algorithm

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375,000 RANDOMLY GENERATED ROUTES

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DATA ACCESS

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DATA ACCESS

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DATA ACCESS

JAVA SERVER

SERVICE SERVICE SERVICE JAVA

SERVER


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SERVICE SERVICE SERVICE

JDBC

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DATA ACCESS

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SERVICE SERVICE SERVICE

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(Yes, it’s a monolith.)

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DATA ACCESS

TRY NOT TO MESS WITH YOUR INTERFACES.

COROLLARY 5.1:

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Oracle'

DATA ACCESS

PRIORITIZE BUG FIXES.

COROLLARY 5.2:

EMBRACE OPERATIONS EARLYRULE 6:

SHEARING LAYERS OF CHANGE TYPES OF REWRITES

LANGUAGE


DESIGNAPI/FRAMEWORK

CODE

PARADIGM…

v v

Stream

Batch

NO MODIFICATION TO THE INTERFACES.

WELL-ENCAPSULATED BUSINESS LOGIC.

CLEAR OBJECTIVE: REDUCE LATENCY.

STRATEGY FOR INCREMENTAL VALUE

SLICESSupports continued development of unaffected layers.

Minimizes opportunities for cross-layer improvements.

OPERATIONS

Dashboards and reports that relied on older forms of operational data had to be rewritten.

OPERATIONS

Engineers were addicted to rebuilding the world when pseudo-reference data changed.

OPERATIONS

Performance expertise was lacking.

OPERATIONS

Our definition of “good” needed radical adjustment.

OPERATIONS

WE HAD TO TOUCH EVERYTHING.

OPERATIONS


SUPPORT CULTURE

DEPLOYMENT STRATEGY

TESTING STRATEGY

MONITORING BEHAVIOR

RISK TOLERANCE

TEAM EXPERTISE

PERFORMANCE MEASUREMENTS

JARGON

CAPACITY PLANNING

DISASTER RECOVERY

ESTIMATION


COROLLARY 6.1:DOCUMENT OPERATIONAL RISKS AND ASSUMPTIONS AS YOU GO

INVEST IN LEARNINGRULE 7:

JUST IN TIME

MULTIMODAL

OBJECTIVE-BASED

LAYERED

WHAT DO WE WANT PEOPLE TO GET OUT OF THIS?

JUST IN TIME

MULTIMODAL

OBJECTIVE-BASED

LAYERED

IS IT AVAILABLE JUST BEFORE THEY

NEED IT?

JUST IN TIME

MULTIMODAL

OBJECTIVE-BASED

LAYERED

DOES IT COVER MULTIPLE VIEWS OF THE SYSTEM?

JUST IN TIME

MULTIMODAL

OBJECTIVE-BASED

LAYERED

DOES IT COME IN VARIOUS SHAPES

AN SIZES?

CREATE LEARNING MATERIALS AS YOU GO.

COROLLARY 7.1:

/** * Documentation is an obvious example of this. * Create and gather assets like: * @param blogs * @param diagrams * @param snippets * @param principles */

http://www.oracle.com/technetwork/java/javase/documentation/index-137868.html#@param




CURATE LEARNING MATERIALS REGULARLY.

COROLLARY 7.2:

/** * Documentation is an obvious example of this. * Create and gather assets like: * @param blogs * @param diagrams * @param snippets * @param principles */








MAKE THE RIGHT THING EASYRULE 8:

PEOPLE CAN BE LAZY.

PEOPLE CAN BE LAZY.ACCEPT IT

MAKE THE WRONG THING HARDRULE 8:

150

55 components

75 essential

black list

EVOLUTIONARY ARCHITECTURE

HOME OF THE VDARA HOTEL

DEATH RAY

Engineering Director, Cerner Corporation Chapter Leader, Kansas City Girl Develop It Conference Organizer, Midwest.io

@michellebrush

MICHELLE BRUSH

Population Health

55 million unique people.

3 petabytes of healthcare data

processing on an 800 node Hadoop cluster

more data is always arriving

let's not rewrite it all

Software