Mobile App Architecture: Coding Standards, State Management, and APIs

Vocabulary flashcards covering core mobile software architecture, visual block programming standards, state management, exception handling, data persistence, and hardware sensor versus web API integration.

Spaghetti Blocks

A messy tangle of unstructured visual block programming logic that becomes difficult to read, test, or debug as mobile applications scale.

Standardized Naming Convention

An engineering rule requiring a 3-letter component prefix (such as btn_, txt_, or lbl_) paired with a camelCase functional name for predictability and maintainability.

Global Scope

A variable scope that remains accessible across the entire application lifecycle and should be used sparingly to prevent accidental data overwrites.

Local Scope

A variable scope strictly confined within an executing block stack that releases its memory immediately upon completion of the block.

Guard Clause

A programming design pattern that evaluates invalid conditions first and exits early before main business logic executes, avoiding deeply nested conditional code.

Fail Fast Principle

The architectural practice of checking for bad or invalid user inputs at the very top of a block stack to halt execution before calculations occur.

DRY Principle

An acronym for 'Don't Repeat Yourself,' stating that if a visual block stack appears more than once, it must be converted into a parameterized procedure.

Void Procedure ('do')

An AppInventor procedure type that executes a designated series of actions without returning an output value.

Function Procedure ('return')

An AppInventor procedure type that executes calculations or data transformations and returns a result value.

Reliability

The probability that software will perform its intended function without failure for a specified duration, anticipating unexpected conditions without crashing.

Efficiency

The degree to which software uses device resources optimally, executing smoothly without unnecessarily consuming memory, battery, or data limits.

State Management

The process of preserving application status, user data, and UI conditions across lifecycle events such as pausing, screen rotation, and app switching.

Transient State

Temporary data (such as active search box text or scroll position) that must survive UI disruptions like screen rotations, but clears when the app is closed.

Persistent State

Long-term data (such as login tokens, preferences, or high scores) stored in non-volatile storage that persists even after the app or device shuts down.

TinyDB

An on-device, non-volatile local storage mechanism offering zero latency and 100% offline access, but whose data is permanently lost if the app is uninstalled.

WebDB

A cloud storage mechanism hosted on remote servers accessible via the internet that facilitates multi-user sync, but requires active connectivity and introduces network latency.

Hardware Sensor

A local physical device component that detects environmental changes or movement and converts them into electrical signals without requiring internet connectivity.

Web API

Application Programming Interface; a software intermediary functioning as a digital waiter that transmits client requests to a remote server and brings data back.

JSON

JavaScript Object Notation; a lightweight, standard text data format utilized by web APIs to return structured information to an application.

API Endpoint

The specific web address (URL) an application queries to retrieve or transmit targeted data via an API.

Motion Sensors

Hardware sensors—specifically the accelerometer and gyroscope—that measure physical tilt, orientation, and device shake.

Position Sensors

Hardware sensors—including GPS and magnetometer—that measure geographic location coordinates and compass heading.

Request-Response Lifecycle

The four-stage API communication flow comprising Request (calling an endpoint), Process (authorization and retrieval), Response (returning JSON), and Parse (UI decoding).