modular architectures: what they are why do they matter now

MODULAR ARCHITECTURES

By Param Rengaiah (@its_param)

March 18, 2014

What they are and why do they matter now.

PROLOGUEHistory matters, at least to me.

This is a three part story.

PART IDefinition, Sort of.

What is

Software Architecture?

The word software architecture intuitively denotes the high level structures of a software system.

- Wikipedia

“

1STRUCTUREOF THE SYSTEM

2PROCESSOF CREATING SUCH STRUCTURES

3RECORDOF THIS STRUCTURE

STYLESArchitecture are indicated in terms of their

MANY STYLES

An useful system always uses

LAYEREDSTYLE 1

PHYSICAL LAYOUT

Focuses on

SERVICE ORIENTED

STYLE 2

INTEGRATION & CUMMINICATION

Focuses on

What is

Modular Architecture?

GOING ONE STEP FURTHER

Modular Architecture is

SMALLER MODULES

Dividing a layer or a service into

deployable, manageable, natively reusable, composable, stateless unit of software that provides a concise interface to consumers. - Kirk Knoernschild

MODULE IS A

“

CHARACTERISTICSOf a module are

1PHYSICALSHOULD BE

2SCOPECLEAR BUSINESS

3 LAYERSCONFINES WITHIN EXISTING

4CONTEXTWORKS WITHIN ITS

5RATE OF CHANGE

SCOPED BY

6 INTERFACEEXPRESSED THROUGH PUBLIC

7STATELESSMODULE INTERFACES ARE

JARA module in Java can be expressed as

COMPOSITION & COMPREHENSION

Focuses on

BENEFITSOf Modular Architectures

1UNDERSTANDHELP US

2EXTENDINGMAKES IT EASY FOR

3DEPENDENCYHELP US MANAGE

Enabling us to

ARCHITECT ALL THE WAY DOWN

Provide us with

DESIGN TIME MODULARITY

RUNTIME MODULARITY

But my system is already modular.

FRAMEWORKDOES NOT MAKE CODE MODULAR

A NEW LANGDOES NOT MAKE CODE MODULAR

SOADOES NOT MAKE CODE MODULAR

PRETTY DIAGRAMDOES NOT MAKE CODE EASY TO UNDERSTAND

PHYSICAL DESIGNIS THE ONLY THING THAT HELP YOU UNDERSTAND, EXTEND AND MANAGE.

PART IIPrerequisites, Sort of.

But why would we want to restructure in the first place?

VISIONARCHITECTS

RESULT IS?

REALITY ISAfter a year or so,

SPAGHETTI

Complicated, difficult to understand,and impossible to maintain is

BRIAN FOOTE JOSEPH YODER

[ Big ball of mud / spaghetti ] systems show unmistakable signs of unregulated growth and repeated, expedient repair.

“

DESIGN ROT

Tightly coupled code with excessive dependencies is known as

ROBERT C. MARTIN (UNCLE BOB)

There are four primary symptoms that tell us that our designs are rotting : rigidity, fragility, immobility, and viscosity.

“

TECHNICAL DEBT

When you choose to defer internal things that will impede future development, you incur

MARTIN FOWLER

Development organizations let their debt get out of control and spend most of their future development effort paying crippling interest payments.

“

Restructuring addresses

1 LOGICALDESIGN FLAWS

MARTIN FOWLER

I see refactoring as a very specific technique to do the more general activity of restructuring.

Restructuring is any rearrangement of parts of a whole.

“

The physical architecture is the skeleton of the system – if it is malformed, there is no cosmetic remedy for alleviating its unpleasant symptoms.

“

JOHN LAKOS

2PHYSICAL& STRUCTURAL DESIGN FLAWS

Restructuring to Modularity.

I was fortunate to have these …

1MODULARITY PATTERNS

A BOOK ON

2 UI MODULESEPERATE

GWT

3 DOMAIN MODEL

SEPERATE

Ubiquitous Language

4 EXTERNAL INTEGRATION

ISOLATED

Clear business context. Explicit boundary. Physical adapters.

5 RULES & WORKFLOW

GROOVY BASED

Essential ComplexityVsAccidental Complexity

Choice between

6DESIGN & ARCH REVIEWS

PERIODIC

Making choices under given context and constraints.

Architecture is about

7 TRUST & FAITH

STAKEHOLDERS SHOULD HAVE

Trusting is one thing, but keeping you on the toe is another.

8 IMPL TEAMROCK STAR

Willing to unlearn what you have known for years.

PART IIIThe works, if you say so.

16 to 82Number of JAR modules

How did we do it?

Arrive at a “Ubiquitous Language” for the domain model.

Simply the lifecycle of managed resources.

Catalog the lifecycle events, triggers, contexts and swim-lanes.

Refactor the domain model to confer to the new ubiquitous language.

Extract core domain model and reference models as separate modules.

Create a separate module to manage each stage of lifecycle for each resource.

Divide the modules further consider rate of change, rate of reuse and for removing cyclical dependencies.

Create a contract module for each external system as it relates to your business

For each of above logical modules, create two physical modules - a spec and an implementation.

Manage physical dependencies through spec modules.

Create deployable modules as a composition of smaller modules (WAR).

Deployed module endpoints are exposed as stateless REST APIs.

Composition provides runtime inter-module integrations.

Composition essentially addresses time and space.

Scalability is baked into composition.

You will arrive at an event-driven, message-driven, comprehensible, extensible, scalable

and maintainable system.

EPILOGUEWhy does it matter now? Finally.

Have you been asked to do any of this?

LETS ADD A MOBILE SKIN

WE SHOULD SUPPORT TOUCH

DEVICES

PUT IT ON THE CLOUD

100% SOA

ITS A SAAS APP BABY!

WE SUPPORT BIG DATA

WE DID “RESPONSIVE WEB

DESIGN”

Modular Architecture prepares you for the future.

Talking about new trends..

REACTIVE ARCHITECTURE

Modular Architecture is an essential facet of RESPONSIVE ARCHITECTURE.

Thank You.Follow me at @its_param