Visual Studio project files, i.e. .csproj and .vbproj files, are MSBuild scripts. When Visual Studio 2005 builds
a project it actually calls MSBuild.exe and passes it the project file. The project files are the starting point of your builds,
and they provide the main entry point for extending the build process
Everything that happens when a project builds is defined in some MSBuild build script.
It follows that every step can be altered, overwritten or removed. In other words,
you could go ahead and write the whole default build process yourself, using MSBuild and the provided tasks.
Most projects use project items that represent files;
The IDE instructs the project to save itself or a project item.
The IDE calls the IPersistFileFormat interface on the project
to indicate that the project should persist its project items as appropriate.
Therefore, the object owns all aspects of its file and format.
This includes the name of the format of the object.
Extension
To determine file name extensions,
projects implement the IPersistFileFormat interface, which provides information enabling the client of an object
to implement the Save As dialog box—that is, to fill in the Save As Type drop-down list and manage the initial file name extension.
Commit model
in a file-based model with local files, each project can be saved autonomously.
In a repository model, you can save several items in one transaction.
When data objects are opened in direct mode,
changes that were made to the data are incorporated immediately or when the user manually saves the file.
When data objects are opened by using transacted mode, changes are saved to a temporary location in memory
and are not committed until the user manually chooses to save the file.
At that time, all changes must occur together or no changes will be made.
Will persisted data objects be opened in direct mode or transacted mode?
How items are saved
IDE examines the running document table (RDT) and
the hierarchy passes the commands to the IVsPersistHierarchyItem and the IVsPersistHierarchyItem2 interfaces.
The IsItemDirty method is implemented to determine whether the item has been modified.
If the item has, the SaveItem method is implemented to save the modified item.
The methods on the IVsPersistHierarchyItem2 interface are used to determine whether an item can be reloaded
and, if the item can be, to reload it. Additionally, the IgnoreItemFileChanges method
can be implemented to cause changed items to be discarded without being saved.