There are three basic ways to get an app on to your device.
App Store
The most common is probably: going to an app store (eg Google Android store or Apple iPhone), picking one, downloading a file directly to your phone (or to a desktop device and through a USB cable to your phone). The file is in an appropriate “installer” format and includes everything needed to install the app on your phone. That means: the program and also any settings and other files needed. Typically these include the program name, the icon to display, the program id (often used as part of where to install the app), and the program version. It can also include a list of what permissions it needs from the user in order to run (access to: internet, location, sms, etc).
On an Android phone the file ends with “.apk” and the program is always a set of java classes. You can do HTML apps on Android but these seem to ship as a set of resources (files / pages) that the java app uses. Your java app simply calls the built-in web browser and turns on a bunch of normal settings such as javascript support.
A Nokia S60 phone is very similar. It’s file ends with “.wgz”. The same settings, files and permissions are present even though they are in a different format. The program is normally a native executable. That is, it runs directly on the device hardware. However, it can also be a set of HTML pages which the installer will automatically associate the built-in browser with.
On Apple the file ends with “.ipa” in the Apple AppStore (see wikipedia .ipa). This is really a “.app” file with some extra bits for the AppStore. (See wikipedia .app but ignore mention of Symbian and note that iPhone also uses an ARM processor).
The install file is really easy to use.
HTML5
The second way to get an app on your device is actually easier. It is SO easy you probably don’t even know you got it.
HTML5 apps on the web include the ability to be downloaded onto your device for speed / performance / bandwidth reasons. If you’ve used one of these, it is on your phone. Once you’ve got it, you no longer need access to the internet. You no longer have to pay for downloaded data (it’s already downloaded). From a developer’s perspective it is the ultimate in making life easy for the user. It is a zero-click download.
The drawbacks are: you don’t even realize you’ve got it, and – at present – none of the browsers contain an uninstall option for these apps.
Probably this will change with time. I really love the simplicity of the installation but we probably need browsers to: pop up a message saying “Application installed” after it downloads the files in the HTML5 manifest, and list installed apps and provide a “remove” option.
The worst fix, which we get sometimes, would be to ask a thousand questions during the install (Are you sure you want to download file 3 of 17? what about file 4? where would you like to save this? An application is trying to install …, Some files can be harmful …, The internet can be harmful …, Technology can be harmful … and so on).
I already have to tap about eight times to call someone on my phone. Let’s not mess apps up too.
ZIP file
The final way to install an app is the hard way. It is a ZIP file containing the program, icons and settings. You unzip the file and copy the contents to your device. You may still need to do some steps to register the app on the device. With a HTML app this can be: open your browser, point it at your installed index.html file, and click the “save favorite” option.
