1. Concurrent Versions System
Overview of CVS architecture.
Repository structure.
Basic development tasks in WinCvs.
Branching and merging.
Other CVS interfaces
CVS internals

2. CVS Features Concurrent access by multiple developers
Multiple development lines in a single repository
Grouping sources into modules
Symbolic source tagging
Diffs between versions
Configurable logging support
Binary files support
Repository event triggers

3. Client-server architecture
separate server (UNIX or NT)
no shared filesystems
a server process per connection
ewacvs

4. The CVS Repository ewacvs:/data1/cvsroot CVSROOT
shr project1 project2 project3 devkits
ar cgi doc install reports util web
cgipr
unix nt
esapps forms
Resides on a server
No working files inside the repository

5. CVS Usage Model Checkout, Commit, Update
Checkout Makes private copy in working directory Can check out anywhere Check out multiple copies, multiple versions
Commit Commit changes to the repository when finished Working copies must be up to date with repository
Update Brings working copy up to date with repository

6. Checkout does not lock the files in repository
Concurrent checkout
Checkout does not lock the files in repository
Master Repository
foo.c
checkout latest
checkout branch rel_1_fix
checkout
V1.1
checkout
V1.2
checkout latest
Karen
Patrick
Michael
Chris
Brigid
Working
Copy
V1.7
Working
Copy V
Working
Copy V1.1
Working
Copy V1.2
Working
Copy
V1.7
checkin
checkin
checkin X X
V1.8 or 1.9 V
checkin prohibited
V1.8 or 1.9

7. CVS and the Development Cycle
1. Check out source files in working directory.
2. Edit source files.
3. Unit test your code.
4. Update working files to merge in changes from other developers (if necessary).
5. Test again if the sources were merged on step 4.
6. Commit changes.
7. Repeat from step 2 until you have a new release.
8. Tag the release.
9. Submit the module name and release tag for integration build.

8. Ideal development with CVS
Developer A
development
update
checkout
checkin
repository
Developer B

9. Real development with CVS
checkin
Developer A
conflict resolution
update
checkin X
repository
Developer B
conflict

10. WinCVS on your desktop
Configuration
Main screen
Checking out the sources
Viewing source history
Diff
Commit
Update
Tag

11. WinCVS: Configuration
Your UNIX login

12. WinCvs: Main screen revision number branch name state icon file type
file view
modules
status view

13. Checking out the sources

14. Source history & diff

15. Commit, Update & Tag
commit
update
tag

16. When to commit
Commit to mark a working state that you might want to return to later.
Commit related files in a single operation. Use a common log message for all the files.
Commit to backup your sources.
Commit from an office desktop to be able to access the files from home much faster than through filesystem sharing.

17. Working on branches 1.2.2.1 1.2.2.2 patch rel_1_fix
cvs tag -b rel_1_fix
cvs up -r rel_1_fix
1.1
1.2
1.3
1.4
release_2
cvs tag release_2
release_1
cvs tag release_1

18. Branch if you need ... to create sustaining (patch) releases
to have multiple development lines from a single repository
to do experimental development to merge later or forget about it
to keep temporary state of development without affecting builds

19. Common CVS commands cvs [cvs-options] command [cmd-options] [files]
cvs checkout Check out source for editing.
cvs add Add new file/directory to repository.
cvs remove Remove an entry from the repository.
cvs status Show status of checked out files.
cvs log Show revision history for files.
cvs diff Compare working files to version in repository or versions inside the repository.
cvs update Bring working files into sync with repository.
cvs commit check files into the repository
cvs tag Label the sources.

20. Diff between 2 versions of the file
Other CVS clients
Diff between 2 versions of the file
Directory listing
CVSweb

21. Diff between 2 versions of the file
Other CVS clients
Directory listing
Diff between 2 versions of the file
jCVS

22. CVS online Official CVS site: http://www.cyclic.com
CVS Bubbles:
CVS for Web development:
WinCvs:
jCVS:
Netscape’s Mozilla under CVS:
FreeBSD CVS repository:

23. CVS Internals
Server is started via inetd (UNIX) with a process per connection
Client-server protocol has embedded compression
Update sends file’s diff across the line, not the whole file (when possible)
UNIX authentication, optional CVS specific passwords/groups, Kerberos and SSH support
CVS does not have to run as root
SCCI and OLE support are in development
Event triggers are implemented via external programs (Perl, sh, C, anything else)

24. Reserved Checkouts and CVS
Exclusive file locking prevents parallel development and is not recommended for plain text files
advisory locks: implemented via cvs edit and cvs watch. Get notification when someone edits or checks in the file.
all-o-nothing advisory locks: cvs edit does not succeed if files are already edited by someone else. Implemented using a patch to cvs edit
exclusive locks (RCS style): implemented via cvs admin. You cannot commit unless you’ve locked the file. One lock per file per branch.

25. Advisory locks Developer A email alert CVS server edit/watch edit
Developer B
Editors:
Developer A
Developer B
Editors:
Developer A