Editing Apache Subversion (section)

==Layers==
Internally, a Subversion system comprises several libraries arranged as layers. Each performs a specific task and allows developers to create their own tools at the desired level of complexity and specificity.

; Fs : The lowest level; it implements the versioned filesystem which stores the user data.
; Repos : Concerned with the repository built up around the filesystem. It has many helper functions and handles the various "hooks" that a repository may have, e.g., scripts that run when an action is performed. Together, Fs and Repos constitute the "filesystem interface".
; mod_dav_svn : Provides [[WebDAV]]/Delta-V access through Apache 2.
; Ra : Handles "repository access", both local and remote. From this point on, repositories are referred to using URLs, e.g.
:* {{mono|file:///path/}} for local access,
:* {{mono|<nowiki>http://host/path/</nowiki>}} or {{mono|<nowiki>https://host/path/</nowiki>}} for WebDAV access, or
:* {{mono|<nowiki>svn://host/path/</nowiki>}} or {{mono|<nowiki>svn+ssh://host/path/</nowiki>}} for the SVN protocol.
; Client, Wc : The highest level. It abstracts repository access and provides common client tasks, such as authenticating users or comparing versions. Subversion clients use the Wc library to manage the local working copy.