1. Revision Control Systems Amin Tootoonchian Kian Mirjalali

2. August 5, 2006Revision Control Systems2 Outline  Revision Control Systems  Samples Subversion ClearCase

3. August 5, 2006Revision Control Systems3  An SCM activity  Controlled and incremental changes  Revision control/Version control/Source control  Management of multiple revisions of the same unit of information  Uses Engineering Software development

4. August 5, 2006Revision Control Systems4 Storage Models  Models Centralized  Shared server  SVN, ClearCase, … Distributed  Changes shared between distributed repositories  No network connection required  TeamWare, GNU arch, …  Compression Delta compression  differences are retained

5. August 5, 2006Revision Control Systems5 Concurrent access  Locking and granting modification access to one developer at a time Protection against difficult merge conflicts (in the case of radical changes possibly) Release of lock!  Allow multiple editing at the same time Facilities to merge changes later Reserved edit  Optional operation to provide exclusive access (by locking)

6. August 5, 2006Revision Control Systems6 Integration  Integration with software engineering process and other tools  Deeper integration with IDEs by using plugins to provide easy access to revision control system Plugins for Eclipse, Visual Studio, Netbeans  e.g. subversion plugin for eclipse

7. August 5, 2006Revision Control Systems7 Terms  Repository  Working copy  Check-out  Commit  Change  Change List  Update  Merge/Integration  Revision/Version  Import  Export  Conflict  Resolve  Baseline

8. August 5, 2006Revision Control Systems8 Subversion  Open Source instance of a version control system Abbreviated to svn in reference to the name of its CLI  Modern replacement for CVS Shares a number of the same key developers

9. August 5, 2006Revision Control Systems9 Subversion – Features  Atomic commits  Renamed/copied/moved/removed files retain full revision history  Versioned directories, renames, and file metadata Entire directory trees can be moved around and/or copied very quickly, and retain full revision history  Versioning of symbol links  Full MIME support

10. August 5, 2006Revision Control Systems10 Subversion – Features (cont’d)  Native support for binary files Space-efficient binary-diff storage  Apache HTTP server as network server  Costs proportional to change size, not the data size  Parsable output, including XML log output  Open Source licensed  File locking for unmergeable file Reserved checkouts

11. August 5, 2006Revision Control Systems11 Subversion – Repository access  Local or network file system, accessed directly  WebDAV/DeltaV (over http or https) mod_dav_svn module for apache2  Custom svn protocol Plaintext Over SSH

12. August 5, 2006Revision Control Systems12 Subversion – Layers  Fs Lowest level Versioned file system which stores the user data  Repos Repository built up around the file system Helper functions/handles various hooks File system interface = Fs + Repos  mod_dav_svn

13. August 5, 2006Revision Control Systems13 Subversion – Layers (cont’d)  Ra Handles repository access both local and remote  Client, Wc Highest level Abstracts repository access Provides common client tasks Wc library used by the client to mange the working copy

14. August 5, 2006Revision Control Systems14 Subversion – File System  Three dimensional Two dimension  Tree structure Third dimension  Each revision has its own root  Files Links to the most recent changes made  Compactness  Transactions used to keep changes atomic

15. August 5, 2006Revision Control Systems15 ClearCase  Rational Software  Large and medium sized projects  Two types: UCM base ClearCase

16. August 5, 2006Revision Control Systems16 ClearCase – Views  Versioned Object Base (VOB)  Multi-version File System (MVFS)  Dynamic views  Snapshots  View-private files  Branch hierarchy

17. August 5, 2006Revision Control Systems17 ClearCase – Configuration Specifications  For each view  Collection of rules: Visible elements in a view Which versions of these elements  “include” statement

18. August 5, 2006Revision Control Systems18 ClearCase – Features  Configuration Record Read files during the build are recorded. Dependency information Use:  Making other views  Applying labels  Build Avoidance Copying over derived objects If they have the same configuration record

19. August 5, 2006Revision Control Systems19 ClearCase – Features (cont’d)  Unix/Windows interoperability Windows clients access by views *nix clients access by snapshot views  Integration with other products Rational Software  ClearQuest, Rational Rose, … Microsoft Visual Studio Eclipse IDE

20. August 5, 2006Revision Control Systems20 References  Wikipedia, the free encyclopedia  Version Control with Subversion - 1.2, O’Reilly Media  IBM Software – Rational ClearCase Documentation

21. August 5, 2006Revision Control Systems21 The END… Questions? Comments? Points of view?