基本概念🔗
Flatpak can be understood through a few key concepts. Familiarizing yourself with these will be useful for learning to use Flatpak from the command line or building applications with it.
运行时（runtime）🔗
Runtimes provide the basic dependencies used by applications. Each application must be built against a runtime, and this runtime must be installed on the host system for the application to run. (Flatpak can automatically install the required runtime for an application.) Multiple runtimes and different versions of the same runtime can be installed alongside each other.
Runtimes are distribution agnostic and do not depend on a particular distribution version. This means that they provide a stable, cross-distribution base for applications and allow applications to work irrespective of operating system updates.
捆绑库🔗
If an application requires dependencies that aren't in its runtime, they can be bundled with the application. This gives application developers flexibility in their choice of dependencies, allowing them to use:
libraries that aren't available in a runtime
different versions of libraries from those available in a runtime
某个库的补丁版本
沙箱🔗
With Flatpak, each application is built and run in an isolated environment called the 'sandbox'. Each sandbox contains the application and its runtime. By default, the application can only access the contents of its sandbox. Access to user files, network, graphics sockets, subsystems on the bus, and devices have to be explicitly granted. Access to other resources, such as other processes, is deliberately not possible.
By necessity, some resources inside the sandbox need to be exported outside to be used by the host system. These are known as 'exports' and include resources such as the application's desktop file and its icon.
门户🔗
Portals are a mechanism through which applications can interact with the host environment from within the sandbox. They enable access to data, files and services without requiring additional static sandbox permissions.
Examples of capabilities that can be accessed through portals include opening files through a file chooser dialog or printing. Interface toolkits can offer transparent support for portals, ensuring secure and out-of-the-box access to resources outside the sandbox.
更多关于门户的学习资源可以在 沙箱权限 找到
仓库🔗
Flatpak applications and runtimes are typically stored and published using repositories, which behave very similarly to Git repositories: a Flatpak repository can contain a single object or multiple objects, and each object is versioned, allowing for upgrades and even downgrades.
Each system using Flatpak can be configured to access any number of remote repositories. Once a system has been configured to access a 'remote', the remote repository's content can be inspected, searched, and used as a source of applications and runtimes.
When an update is performed, new versions of installed applications and runtimes are downloaded from the relevant remotes. Like Git, only the parts that have changed between versions are downloaded, making the process very efficient.