Lublin Startup Festival - Mobile Architecture Design Patterns

MOBILE APP DEVELOPMENT ARCHITECTURE & DESIGN PATTERNS

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EXPERIENCE

ABOUT ME

Karol Szmaj

[email protected]

VP, CTO

+48 725 787 006

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Agenda

Out of the box approach

MVVM

Inversion of Control

Command and Query Responsibility Segregation

Tools & Tips

1

2

3

4

5

6 Questions

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DESIGN PATTERNS ARE SET OF GUIDELINES NOT RULES

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Can be overkill for very simple application

Requires more time to bootstrap app

architecture

Disadventages

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Design Pattern Overview

Simplify maintenance

Separation of concerns

Minimize logic needed in UI

Enable testability

Reduce development time

Easy to customize apps

Adventages

OUT OF THE BOX APPROACHCODE BEHIND

1

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Fast app prototyping

No time required for bootstraping application

Simple design: action + handler

Easy access to visual tree

Pros

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Out of the box approach

Code Behind

Large view classes

Breaks Single Responsibility Pattern

Hard to mantain in future

Poor code readability

UI customization can break logic inside view

Cons

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Out of the box approach

Code Behind

Creating small MVP of your product if there is an opportunity to refactor

Testing features

Small apps

When you should use it?

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When you shouldn’t use it?

Creating MVP without time to refactor

Enterprise apps

For apps with long-term support

Out of the box approach

Code Behind

MVVM –MODEL VIEW VIEWMODEL

2

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MVVM

Model-View-ViewModel

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Notifications

Data Binding

Commands

View ViewModel Model

UI Logic

Code Behind

Presentation

LogicBussiness Logic

And Data

Creating long term-support apps

When considering unit testing

When we need better code mantainability

When you should use it?

MVVM

approach

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When you shouldn’t use it?

For app testing purpose

When we don’t need testable bussines logic

When project is very simple (avoid architecture overengineering)

Lightweight

Developer controls everything

Implements: Command Patern, ViewModelBase, Messenger

Has IoC Container

MVVMLight

MVVM

frameworks

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WinRT focused

Support C#, C++/CX and HTML/JS

Validation, Conventions, Attached Events, Messenger, Logging

Very modular

Has IoC – Grace Container

StyleMVVM

MVVM

frameworks

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More complex, harder bootstrap

Better support for View Composition

Event aggregator

Conventions, Coroutines

Stable!

CaliburnMicro

MVVM

frameworks

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IOC – INVERSION OF CONTROL

3

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It’s not a library, framework or tool

It’s like a way of thinking, designing code and general guidelines

Dependency Injection is a set of practices that allow to build loosely coupled

applications

DI & IOC

What is it?

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Small components that are: independent, reusable, interchamgeable

We gain such benefits like: small classes (SRP), easy maintenance,

extensibility and testability

Dependency Injection is a set of practices that allow to build loosely coupled

applications

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DI & IOC

What is it?

IoC

Classic design

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ClassA ClassB

ClassC

ClassD

creates

IoC design

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ClassA ClassB

ClassC

ClassD

requires

Container

Model

Instance of ClassA

GetInstance

CQRS

4

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Query stands for reading

Commands stands for writing

Command/Query Responsibility Segregation (CQRS) is the idea that you

can use a different model to update information than the model you use to

read information (web experience).

CQRS

What is it?

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CQRS

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ALL OF THIS TO PROVIDE SCALABILITY & A CONSISTENT

VIEW OF THE DATA.[WEB]

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Classes are responsible for doing one particural job

Easy testability, extensibility and readability

Easy to mantain

Can be shared via multiple projects (portable)

Adventages of CQRS in mobile application:

CQRS

Why do we need it?

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TOOLS & TIPS

5

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MrAdvice – AOP tool

MethodTimer – decorates method with a timer

NullGuard – useful for Defensive Programming

Visualize – DebuggerDisplay weaver

Fody is a extensible tool for weaving .net assemblies

Tools - Fody

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Polly is a .NET 3.5 / 4.0 / 4.5 / PCL (Profile 259) library that allows

developers to express transient exception handling policies such as Retry,

Retry Forever, Wait and Retry or Circuit Breaker in a fluent manner.

Tools - Polly

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await Policy .Handle<SqlException>(ex => ex.Number == 1205) .Or<ArgumentException>(ex => ex.ParamName == "example") .RetryAsync()

.ExecuteAsync(() => DoSomethingAsync());

Cimbalino Toolkit is a set of useful and powerful tools that will help you build

your Windows Platform applications.

Tools - Cimbalino

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Supports:

Windows Phone Silverlight 8.0+

Windows Phone / Windows Store 8.0 (WinRT)

Universal App Platform (Windows 10)

What do we get?

Tools - Cimbalino

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Behaviors

Converters

Extension classes

Services

Helpers

What do we get?

Tools - Resharper

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Better IntelliSense

Great refactor tool

XAML Support

R# just rocks!

Better to:

Tip #1 – Universal Apps 8.1

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Separate styles and templates using stalellite libraries

Add ViewModels to portable library NOT to shared project

Design your app architecture to support multiple platforms like Xamarin

Design your project to support adapter pattern

Throwing exceptions from layers is not the best way to handle errors

What do we get?

Tip #2 – Windows 10 XAML

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Improved XAML performance

x:Bind – faster compiled binding

Adaptive design

.Net Native

App design guidelines

Tip #3 – Xamarin

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Design your code logic to be not dependant on specific platform

Test your code on each platform

Don’t code without thinking about the problem

Design your code to be simply and readable.

Don’t overengineer your app

QUESTIONS?

Karol Szmaj

[email protected]

VP, CTO

+48 725 787 006

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