Classes details

The file system transparency improves the package management usability a lot. We are going to examine in depth the PackageFS structure and the technical implementation in order to see how we reach our goals.

As we said PackageFS is written in C++ programming language, and has been developed using Object Oriented Programming paradigm. Thus the whole structure is kept clean, easy to be represented (see figure 5.6) and discussed.

At the moment PackageFS consists of few classes:

• PKGFS that implements the overrider system calls;
• Ventry and Vtree that manage the virtual tree storing the file system data;
• PkgMgr that provides a common interface to low-level package managers;
• PkgDebian that directly interacts with the Debian APT package manager;
• PKGFSCache that saves time during the PackageFS mount operations.

Figura 5.6: The whole PackageFS structure.

• PKGFS
  • Public methods
  • Protected methods
  • Private data
  
  
• Vtree and Ventry
• PkgManager
  • Cache operations
  • Single package operations
  • Real applications execution
  
  
• PkgDebian
  • pkgCacheFile
  • pkgCache::PkgIterator
  • extern Configuration *_config
  • Public methods implementation
  
  
• PKGFSCache