Mobile applications

When we talk about a mobile application, we usually mean a program that is designed to run on a mobile device, such as a smartphone. These devices have some special characteristics that we need to consider when writing an application. First, their screen is smaller than a computer monitor. The screen can also be rotated in landscape or portrait orientation. We will also use the touchscreen of the device for input.

The mobile application might also use other features of the device, such as the GPS, sending text messages, or sensing the movement of the device using its accelerometer. These are things we usually can't do if an application runs on a normal computer.

A mobile application can be connected, but it does not have to be. Being connected means that it can communicate with another computer, maybe using the client-server techniques we discussed earlier.

When writing a mobile application, the platform the application will run on is very important. The reason is that the programs we write need to interact with the device more directly. This means is that it can dictate what programming language we will use to write these applications. The developers of the operating systems for mobile devices have some preferred programming languages. For iOS, Apple's operating system for mobile devices uses two languages, the old Objective-C and the new Swift. These are two languages you will hardly ever encounter if you are not creating applications for Apple devices. For the Android operating system, the preferred language used to be Java, but Google, which is the company behind Android, changed this in 2019 and now use a language called Kotlin as the preferred development language.

Having a preferred language for these systems does not mean that we can't use other languages. Still, Apple and Google recommend using these languages, so it is usually easier for us to use these languages when developing mobile applications. The reason is that the tools we use when writing our programs will be better suited to them than any other language.

Next, we look at distributed applications.