Strategic software design

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Strategic software design

context

common results

system becomes more & more

unstable

unreliable

refactor

goes on for ever

concepts just copied rather than reworked

old legacy is more complex than expected

never gets finished

common solutions

hack

Subtopic

refactor legacy

system 2.0

replace legacy with new system

problem

new features don't map to legacy system

irresponsible hero's

much credit

even though

their solution

has a high cost of delivery

which usually remains invisible

caused instability

is fixed by people

competent

responsible

quite

because they work in

close to business needs

CORE domain

4th solution

Model the elephant

model of elephant

in the context of a single BoCo

an elephant

can be described accuratley enough as a tree

could be a wall

supported by 4 trees

withe a snake

and a rope attached on either end: -)

describes the elephants features needed in a certain context

is NOT the elephant

hindu story

blind people try to describe an elephant

touching trunk

elephant is a snake

touching tail

elephant is a rope

touching knee

elephant is a tree

touching side

elephant is a wall

create Bounded Contexts (BoCo)

start with platform

then build on top of that

the Core Domain

(or within its safe border)

anti corruption layer

often an ugly layer

alternative is

introducing even more mudd in the ball of mud

translates

interfaces with

the big ball of mud

and stay consistent in this context only

eg allow duplication between BoCo's

Focus on CORE domain

don't fix 'everything'

Domains

Core domains

usually relatively small

need to be developed

colocated & close to business

by best & most responsible developers

directly relates to

and how software is used to leverage that strategy

strategy of the company

which often needs to change

due to market conditions

eg: seller rating by users/buyers

Supporting domains

eg: amazon book rating by users/readers

if needed

can be outsourced

specific to your business but not core

Generic Domains

should be

produced as cheap as possible

outsourcing

bought

not specific to your business

understood by other companies as well

eg : accounting