Windows 8: How is a Metro application
Table of contents:
- The interface of a Metro application: the toolbars and navigation
- Beyond Full Screen View
- The Metro Application Execution Model
- The disadvantages: more limitations than traditional applications
- Special Windows 8 In Depth
Windows 8 introduces a new type of applications, Metro or Modern UI-style applications according to the latest Microsoft names. They are not applications that we are used to, at least not on a computer. Therefore, in this installment of our special we are going to delve into what a Metro application is like and how it works.
The interface of a Metro application: the toolbars and navigation
The main concept behind Metro is that the most important thing is the content.For this reason, in Windows 8 the applications will have rather few controls in the interface, which will focus on showing us text, video, images or whatever. However, we still need the controls, we can't go around doing everything with gestures. For this reason, Metro applications have certain common interface elements that help us to do certain tasks: the main one is the App Bar or the toolbar.
This bar contains all the commands that we can use in each of the application screens, and the most important thing about it (and the main difference with that of Windows Phone) is that it is contextual, it is adapts to what we are doing .
The App Bar is hidden when we are using the application and it will not appear until we swipe from the bottom of the screen. The reason? Normally we don't need the commands that are there, and it's less annoying if it's hidden and only brought out when necessary.
However, there are some situations where we do need that slash. For example, when we are selecting several elements, the most likely thing is that we want to do something with them: delete them, add them to a folder... Therefore, when you select several elements, the lower bar automatically appears, which will have the buttons you need.
Applications can also incorporate a top navigation bar , which appears when you swipe from the top of the screen. This bar allows us to go to the different sections of the application or go back if the application has a linear navigation system.
Not all applications implement it in the same way: for example, in Internet Explorer it is used to navigate between tabs, in its Store to go to the different sections... Microsoft does not force a common design, but it does invite that the purpose of that bar is always to move between the different parts of an application.
Beyond Full Screen View
Metro also brings a change of concept when it comes to how applications appear on the screen. When we work normally with them they will be maximized, but we have other possibilities when executing them. For example, we can stick the applications to the side of the screen, occupying only a third of the space.
Keep in mind that it's not just changing the size but also displaying things differently than they are displayed in full screen, and it's the developer who has to implement the interface that best suits to this mode.
"On the other hand, we can also run Metro applications through the charms. Let&39;s say that we are watching a piece of news and we want to share it. Using the share button on the right bar we can choose an application, which will execute a dialog>"
It is also the difference with desktop applications. In Windows 7, to share from one application to another we drag and drop (or copy and paste); a rather crude method from the developer's point of view. In Windows 8 it is the system that allows applications to communicate with each other, thus opening the doors to richer interactions.
On the other hand, Microsoft has marked differences with other mobile systems and tablets. The fact of having several applications on the screen, despite being such a simple concept, is something that neither Android nor iOS had done, and that is really useful when we have a tablet with a sufficient screen. It is one of the advantages of Windows 8 being a system that comes from the desktop and not from the mobile.
The Metro Application Execution Model
When opening a Metro application for the first time, surely the fact that it does not have a close button has caught your attention. It is something more typical of a mobile application than a normal Windows application. You may have also noticed that when the application is not on the screen it does nothing, it stays frozen.
These differences give us the three possible states of a Metro application: running, suspended, and stopped (Not Running). When we first launch the app, it goes into the running state where we can interact with it. If we switch to another application, the state becomes suspended: Windows saves the state of the application in memory but pauses all the processes it has running .
As long as the application is suspended and there is memory, Windows will continue to save its state. When you return to it by changing applications or clicking on its icon again, it will reactivate and recover its previous state. If, on the other hand, there is not enough RAM, Windows will close the application completely. When you run it again, it will not recover its state automatically and will run from the beginning, unless the developer has programmed it to save recovery data on shutdown.
As you can see, this is a model more typical of a mobile than a computer, and it also entails a change of mentality when using these applications.There is no need to kill Metro applications when you have many applications on the computer because the system already does it automatically.
"We don&39;t have to worry about closing an application when we finish using it either. First, because from our point of view a suspended application does not hog system resources, there is nothing wrong with leaving it there. And second, because we can&39;t even do it: there is no kind of option to exit, not even pressing the back button continuously like in Windows Phone."
The disadvantages: more limitations than traditional applications
As I said before, Metro applications bring many interesting mobile concepts. Unfortunately, they also come with limitations that developers have to abide by, sometimes because the WinRT API doesn't give them a choice, and sometimes because they won't accept apps in the Windows Phone Store.
The first is how applications are distributed. They have to be fully contained in the application package, they cannot download additional executable components in order to work. This means no use of frameworks like Java, and applications with multiple binary components (for example, a LaTeX distribution) have to manage to put everything together in a single package, without downloading anything to userspace.
We also have more technical restrictions on accessing low-level system APIs. For example, Sockets cannot be used, which breaks compatibility with many existing libraries, and also prevents creating more complex applications that transmit data over the network.
Metro also enforces the fact that applications are isolated from each other. This prevents application launchers from being created, the features of Metro applications cannot be modified, and they cannot communicate with each other in a way other than sharing files... It closes a lot of possibilities with respect to what we have on the desktop .
And all this together with the restrictions that Microsoft applies to the Windows Store: content that may be offensive to some, security applications that can be detected as malware... If something is found in the review process that violates the rules, the app will be rejected and will not reach users until the bugs are fixed.
These limitations support the idea that Metro applications are not going to serve to do serious work on the computer. Personally, I don't entirely agree (with a Metro application you could create a UML design for a complex application, for example), but it is true that they are not going to be applications with as many possibilities as desktop ones .
On the other hand, since they are simpler applications and with more closed functionalities, they will be much easier for users to use. The crux of the matter is finding a balance between a common interface and behaviors and the freedom given to developers, and I think Microsoft has managed to find the sweet spot with the Metro apps.
