Concurrent Versions System

1
Concurrent Versions System

• Overview of CVS architecture.
• Repository structure.
• Basic development tasks in WinCvs.
• Branching and merging.
• Other CVS interfaces

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
The CVS Repository
ewacvs/data1/cvsroot
CVSROOT
shr project1 project2 project3 devkits
ar cgi doc install reports util
web

unix nt
cgipr
esapps forms

• Resides on a server
• No working files inside the repository

4
CVS Usage ModelCheckout, Commit, Update

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

5
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.

6
Common CVS commands

• cvs cvs-options command cmd-options files
• cvs checkout Check out source for editing.
• cvs update Bring working files into sync with
  repository.
• cvs commit check files into the repository
• 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 tag Label the sources.

7
When to update/commit

• Update frequently so you have the most recent
  changes in your private copy.
• Commit only when you have automated, passing,
  unit tests for the module you are committing.
• You may commit related files in a single
  operation. Use a common log message for all the
  files.

8
Ideal development with CVS
Developer A
checkout
update
checkin
development
repository
Developer B
9
Real development with CVS
Developer A
repository
Developer B
10
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

11
Working on branches
12
Client-server architecture

• separate server (UNIX or NT)
• no shared filesystems
• a server process per connection

ewacvs
13
WinCVS on your desktop

• Configuration
• Main screen
• Checking out the sources
• Viewing source history
• Diff
• Commit
• Update
• Tag

14
CVSweb
Other CVS clients
15
jCVS
Other CVS clients
16
CVS online

• Official CVS site http//www.cvshome.org
• WinCvs http//www.wincvs.org
• jCVS http//www.jcvs.org/
• TortoiseCVS http//www.tortoisecvs.org/

17
OBSOLETE SLIDE!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
Brigid
Michael
Chris
commit
checkin
checkin
X
X
V1.8 or 1.9
V1.2.2.2
checkin prohibited
V1.8 or 1.9