Types & Best Practices In 2024

Mobile App Architecture: Types, Best Practices & More

Mobile apps have become an integral part of our daily lives. We use apps for communication, entertainment, productivity, health and fitness, and more. With billions of mobile app downloads yearly, mobile apps are big business. But what exactly goes into building a robust, scalable, and successful mobile app? The answer lies in having a well-planned mobile app architecture.

Understanding Mobile App Architecture

Mobile app architecture refers to the underlying design structure of an app. It encompasses the key components that make up an app, how they interact and communicate with each other, the technologies and frameworks used, and the overall infrastructure that allows an app to function efficiently across different platforms and devices. Sound mobile architecture is crucial for building stable, secure, and scalable apps. It also ensures the maintainability of the codebase in the long run.

Why Mobile Architecture Matters

Here are some key reasons why having a clearly defined architecture is essential for mobile app development:

• Facilitates collaboration and scaling of teams: With a modular architecture, multiple developers can work simultaneously on different modules of an app. This parallel workflow enables faster time-to-market.
• Improves quality and robustness: A structured architecture promotes the reuse of standardised components which are thoroughly tested. This improves overall quality and robustness.
• Supports maintainability: A modular design with loose coupling makes the app easier to maintain and build upon in the future without lots of rework.
• Enhances security: Security measures like certificate pinning, token-based authentication, etc., can be incorporated to protect app data and prevent attacks like code injection data leaks through proper architecture.
• Enables scalability: The app can handle growth in users, data volumes, features, etc., in the future through appropriate architecture patterns like microservices.
• Simplifies adding new features: Adding new features becomes more accessible through modular architecture as existing components can be reused and repurposed.

Mobile architecture is not something that can be bolted on as an afterthought. It requires upfront, strategic planning before you write your app’s first line of code!

Elements of Mobile App Architecture

The mobile app architecture can be logically broken down into four key aspects:

1. App infrastructure
2. Navigation structure
3. Data storage strategy
4. Communication protocols

Let’s look at each of these elements briefly:

1. App Infrastructure

The app infrastructure primarily consists of the following:

• Platform: The operating system and hardware environment where the app will run, e.g. iOS and Android, are the dominant mobile platforms.
• Frameworks: The software frameworks and libraries like React Native, Xamarin, Flutter, etc., are used to build the app.
• Cloud services: Any cloud-based functionality like push notifications, remote configuration, etc., enabled through Firebase or AWS.
• Tools: Software tools supporting activities like code repository, tracking issues, continuous testing and integration, e.g. GitHub, Jenkins, etc.

Choosing the right technologies and tools per the app requirements, team skills, and resources is very important upfront.

2. Navigation Structure

The navigation structure defines how different screens or modules of your app are interlinked and sequenced to provide a smooth user flow. Some common mobile navigation patterns are:

• Simple linear flow: Suitable for simple apps having a predefined sequence of screens
• Hierarchical navigation: Complex apps having nested, multi-level flows like email app folders
• Tabbed navigation: For quick navigation between peer app sections through tabs
• Dashboard: For complex apps, providing a central area from where you can reach other sections

3. Data Storage Strategy

Data strategy determines how the app stores, transforms, and syncs data across various tiers, such as devices, servers, databases, or cloud services. Strategies include:

• Local storage: For offline access, use SQLite databases or mobile OS-provided data stores
• Server DB: For heavy, complex data requirements, use relational or NoSQL databases
• Cloud services: For lightweight data security, push notifications, etc., use BaaS like Firebase
• File storage: For multimedia storage like images, audio, videos, etc., use mobile OS-provided mechanisms or cloud buckets.

Choosing optimal storage per access patterns, volume and freshness needs is crucial.

4. Communication Protocols

Standard network communication protocols like HTTP, WebSockets, MQTT, etc., enable the app modules to reliably send, receive or exchange data across distributed components as per the networking constraints of mobile apps. Security is also built on these standard protocols through tokenisation, encryption, etc.

Now that we understand the critical constituents of mobile app architecture let’s look at some common architectural patterns.

Mobile App Architecture Patterns

Specific proven architecture patterns have emerged based on mobile apps’ complexity and specific functional needs. Let’s examine the popular ones:

Monolithic Architecture

This simple, single-tiered software architecture packs all aspects of an app into one software unit. Here’s how it looks:

Key Characteristics:

• All app capabilities are packed into a single software unit
• No modularisation of capabilities
• Direct function calls between modules
• Suited for simple apps with small codebases and teams

Pros: Simple to develop, test and deploy

Cons: Lacks flexibility and scalability for complex apps

Monolithic works best for straightforward apps like simple games, widgets or utilities where all developers work on a single codebase.

Client-Server Architecture

This segregates an app into a thin client running on the mobile device and the bulk of the app logic encapsulated in a server.

Key Characteristics:

• Stateless client for UI and validation logic
• Stateful server for business logic and data access
• Communication over network protocols

Pros: Easier to scale and maintain. Client complexity reduced.

Cons: Network dependency. Increased latency.

This architecture is the starting point towards modularising complex enterprise apps with extensive server-side logic.

MVC Architecture

The Model-View-Controller (MVC) is another flavour of client-server architecture tailored to apps with sophisticated UI.

Here’s what each component focuses on:

• Model: Manages data, business logic and state
• View: Renders UI and outputs to display
• Controller: Handles inputs and delegates requests between View and Model

Key Characteristics:

• Strict separation of UI layer from business logic and data access logic
• Suited for complex, interactive UI needs
• Popular variants like MVVM also exist

Pros: Promotes modularity, parallel workflows

Cons: Complex to implement for more superficial apps

MVC is great for e-commerce and workplace apps with rich, dynamic UIs but leaner mobile clients.

Microservice Architecture

In this distributed architecture style, an app is built as an ecosystem of finer-grained, independently deployable microservices:

Key Characteristics:

• Functionalities split into autonomous services
• Services can be independently developed, tested, deployed
• Individual scaling capability per service
• Communication via APIs

Pros: Highly scalable. Enables continuous delivery.

Cons: Complex to create, orchestrate, test and monitor

Microservices shine for internet-scale apps needing extreme performance, availability and scaling needs. Examples include Netflix, Amazon, and Uber.

Offline-First Architecture

For apps expecting flaky networks or needing offline access, sensitive data is stored locally on-device while external connectivity is used judiciously.

Key Tenets:

• Local central data store
• Critical app logic on the device
• Graceful handling of offline states
• Background sync with the server

Pros: Unfettered offline access maximises engagement

Cons: Tricky race conditions between local and cloud data

Offline-first is excellent for apps used in remote areas or needing always-available data access like personal health monitoring, industrial internet, etc.

This covers the major architecture styles used for mobile apps. The optimal choice depends on app objectives, functional complexity, target devices, networking needs and team composition.

Now, let’s look at best practices for crafting resilient mobile architectures.

Best Practices for Mobile Architecture

Here are some essential best practices to create smooth, scalable mobile app architectures:

Practice Modularity

Decompose the app into loosely coupled modules that group related capabilities and dependencies. For example, break down modules across screens, business capabilities like order management or payments, utilities like notifications or logging, data layers, etc.

Benefits of modularity:

• Parallel development of modules speeds up delivery
• Reduces complexity by abstracting implementation details
• Improves reusability across apps
• It is more straightforward to test modules in isolation
• Changes can be isolated to minimise the impact
• Mix-and-match modules to create variants

Build Resilient Communication

Standard protocols decouple interconnected modules:

Choose standard network protocols like REST, GraphQL or streaming protocols like MQTT WebSockets for communication:

• Reduce direct dependencies between app modules
• Enable modules to be developed and scaled independently
• Effortless integration with external services
• Easier to maintain and extend communication contracts

Complement protocols with:

• Timeouts, retry logic for transient network issues
• Caching frequently accessed data where freshness allows
• Queueing requests to smooth out peaks

Design for Offline Access

Allow critical functionality without connectivity:

• Store relevant data locally for offline access, e.g. using SQLite
• Queue requests for later submission to the network
• Handle offline exceptions gracefully, e.g. alerts
• Enable background sync to reestablish server state

This avoids frustrating users when networks are poor.

Incorporate Security Best Practices

Address security early into architecture:

• No hard-coded secrets or keys
• Encrypt local file storage
• Token-based stateless auth with short validity
• Validate all inputs and sanitise outputs
• Certificate pinning from client to servers

This reduces attack surfaces like injection attacks, leaks, etc.

Plan for Scalability

• Horizontal scaling through small single-responsibility services
• Database sharding read replicas
• Asynchronous processing through message queues
• Load testing for capacity planning

This allows cost-effective growth in transaction volumes.

Optimising the Performance of Mobile Apps

Performance is a make-or-break criterion for mobile apps. Users expect fast-launching apps, quick navigation, instant visual feedback and crisp response times. Here are vital considerations for performance-tuning apps:

Reduce App Size

Large app sizes lead to higher download times and consume device storage:

Tips to reduce app size:

• Code minification to remove whitespaces, comments
• Eliminate unused resources like images, libraries
• Split optional components, games, and modules for on-demand downloads
• Compress image and media assets without affecting quality

Optimise Data Transfer

Unoptimised network calls lead to slow page loads and high latency:

Tips to optimise data transfer:

• Image compression/resizing to reduce payload
• Caching frequently needed data locally
• Batching multiple requests into a single network call
• Compressing API response payloads
• Throttling update frequency of dynamically updating screen data

Choose Efficient Data Structures

• Favour array lists over vectors when iterating over entire data sets
• Use object pools instead of creating new objects
• Pre-allocate capacities to avoid runtime resizing for structures like arrays, maps

Analyse Critical Paths

• Measure execution times of critical user journeys using profiling
• Identify heavy operations executing on the main/UI thread
• Shift-blocking operations like fetching data from databases or networks to background threads

Benchmark Regularly

Assess key metrics like app size, data usage, battery drain, network requests, etc., regularly using Android Studio or Xcode profiling. This pinpoints regressions before they impact users.

By meticulously following these coding best practices, mobile apps can deliver slick experiences even on mid- or low-end mobile devices.

Testing Mobile App Architecture

Given the complex environments in which mobile apps operate, rigorous testing is imperative to ensure a high-quality bar. Let’s see how testing fits into the mobile architecture.

Scope of Testing Mobile Apps

Due to the diversity of devices and platforms mobile apps support, testing has to cover multiple dimensions:

• Unit Tests: Validate logic within individual classes/functions
• Integration Tests: Verify interactions between integrated modules end-to-end
• API or Interface Tests: Validate application interface behaviours independently
• System Tests: Test complete systems encompassing devices, native OSs, networks
• Acceptance Tests: Confirm apps meet user stories across real-world conditions
• Compatibility Tests: Verify compatibility across target iOS and Android OS versions and device models
• Localisation Tests: Check functionality across intended languages & regional data formats
• Compliance Tests: Certify policy compliance, e.g. accessibility, security, privacy

As you can see, testing mobile apps requires a multi-layered approach spanning multiple test dimensions.

Implementing Test Automation

While manual testing plays an initial role, test automation is critical to keep pace with rapid iterations during agile mobile app development:

Key enablers of test automation:

• Test frameworks like Appium, Espresso, XCTest
• CI/CD pipelines to trigger automated testing suites
• Cloud testing labs for on-demand testing across vast device grids
• Visual scripting tools to enable coding-free test creation

Benefits of test automation:

• Accelerates testing by 10X or more
• Enables extensive test scenarios challenging via manual testing
• Consistent tests unaffected by human errors
• Effortless regression testing with overnight test runs
• Quantifiable metrics to track quality over time

Specialised testing tools can test security, performance, data usage, etc. Leverage multiple tools aligned to your needs for round-the-clock testing.

Case Study: Ecommerce App Architecture

Let’s see a case study on architectural design decisions in developing a shopping app for selling household goods to consumers.

App Capabilities

The ecommerce app must enable the following:

• Browse and search product catalogs with filters
• Add products to cart and manage cart
• Check-out ordering workflow
• Payment integration
• Order history and status tracking

Additionally, the app requires:

• Persisting product inventory statuses in real-time
• Consistency between web and mobile views
• High performance for product images and interactive catalogue
• Offline support for orders

App Infrastructure

• Platform: Native apps for Android and iOS with maximum code reuse
• Frameworks: React Native for device OS integration; NodeJS for server
• Cloud: AWS for deployment; S3 for storing images
• Tools: Git; Jest for Testing; Fastlane for iOS builds; AppCenter for monitoring

Navigation Design

Tab-based navigation allows access to modules through tabs:

• Home: Landing screen for promotions; Search entry
• Browse: To explore the catalogue organised by categories
• Cart: For checkout workflow
• Account: Order history and account management

Hierarchical views display product drill-downs.

Data Storage

Multiple data storage options are required owing to diverse data access needs:

• Server MySQL DB: For inventory, order data requiring reliability and complex querying
• On-Device SQLite: For customer data security and offline needs
• Cloud Storage: For storing product images in AWS S3 for high performance
• In-Memory Caching: For better response times to catalogue queries

Communication Protocols

• REST APIs: For all server communications
• WebSocket: For real-time order status pushed from the server to clients
• Message Queues: To smooth order request peaks

Offline Support

• Catalogue product data is synced weekly to a device for browsing without connectivity.
• Orders saved locally and synced on reconnect automatically

The ecommerce architecture uses patterns like tabbed navigation, optimised data tiering and communication middleware to satisfy the app’s performance, scalability and offline usage demands.

FAQs on Mobile Architecture

Here are some additional common questions about mobile architecture: