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Version Control
CS 370 SE Practicum, Cengiz Günay
(Some slides courtesy of Eugene Agichtein and the Internets)
CS 370, Günay (Emory) Version Control Spring 2014 1 / 15
Agenda
Make-up lecture:
Diagrams useful for your project designsWatch it and do survey by Thursday 3/27
Project milestone:
4/10 functional prototype opens for testing
Other news:
May collect some experienced entrepreneurs/venture capitalists to seeyour projects at the end of semester
Today: Version control
Centralized: Subversion
Distributed: GIT
CS 370, Günay (Emory) Version Control Spring 2014 2 / 15
Agenda
Make-up lecture:
Diagrams useful for your project designsWatch it and do survey by Thursday 3/27
Project milestone:
4/10 functional prototype opens for testing
Other news:
May collect some experienced entrepreneurs/venture capitalists to seeyour projects at the end of semester
Today: Version control
Centralized: Subversion
Distributed: GIT
CS 370, Günay (Emory) Version Control Spring 2014 2 / 15
Agenda
Make-up lecture:
Diagrams useful for your project designsWatch it and do survey by Thursday 3/27
Project milestone:
4/10 functional prototype opens for testing
Other news:
May collect some experienced entrepreneurs/venture capitalists to seeyour projects at the end of semester
Today: Version control
Centralized: Subversion
Distributed: GIT
CS 370, Günay (Emory) Version Control Spring 2014 2 / 15
Agenda
Make-up lecture:
Diagrams useful for your project designsWatch it and do survey by Thursday 3/27
Project milestone:
4/10 functional prototype opens for testing
Other news:
May collect some experienced entrepreneurs/venture capitalists to seeyour projects at the end of semester
Today: Version control
Centralized: Subversion
Distributed: GIT
CS 370, Günay (Emory) Version Control Spring 2014 2 / 15
Why Version Control?
It's a must in today's computing industry
I Mt. Gox, a company that don't use VC and lost almost a billiondollars. . .
I Other painful stories without VC
You can even version control documents, class �les, �nancial �les, . . .
Also called source control, code management, concurrent versioning,revision control, . . .
Advantages:
I Track changes, keep logs of past developmentI Automatic backups/safety netI Concurrent versions: XP vs. Win8I Allows teamwork
CS 370, Günay (Emory) Version Control Spring 2014 3 / 15
Why Version Control?
It's a must in today's computing industry
I Mt. Gox, a company that don't use VC and lost almost a billiondollars. . .
I Other painful stories without VC
You can even version control documents, class �les, �nancial �les, . . .
Also called source control, code management, concurrent versioning,revision control, . . .
Advantages:
I Track changes, keep logs of past developmentI Automatic backups/safety netI Concurrent versions: XP vs. Win8I Allows teamwork
CS 370, Günay (Emory) Version Control Spring 2014 3 / 15
Teamwork on the same codebase: How?Seriously, how?
CS 370, Günay (Emory) Version Control Spring 2014 4 / 15
Teamwork on the same codebase: How?Seriously, how? No control? Overwrite chaos!
CS 370, Günay (Emory) Version Control Spring 2014 4 / 15
Teamwork on the same codebase: How?Seriously, how? Locking
CS 370, Günay (Emory) Version Control Spring 2014 4 / 15
Teamwork on the same codebase: How?Seriously, how? Merging
CS 370, Günay (Emory) Version Control Spring 2014 4 / 15
Each commit/check-in increments version
What is Subversion?
• A centralized version control system
• Not the newest form of configuration management, but easy to use and popular– Founded in 2000– Successor to widely used CVS
• Aka SVNSlide 6
Repository
Centralized version control: Subversion (SVN)
Documentation
http://svnbook.red-bean.com/
Common SVN usage scenario:
1 svn checkout gets working copy from repo
2 Make local changes in working copy
3 svn update gets latest changes from repo to sync
4 svn commit (or checkin) sends your changes to repo
Investigating the past
svn diff shows your changes from last repoversion
svn diff -cX shows changes in version X
svn log [filename] shows all commit logs
Example: How to �nd a bug
1 You have been messing with the code
2 Suddenly you realized you broke the program
3 How do you �nd when was the bug introduced?
4 Hint: Can go back with svn update -rX
Investigating the past
svn diff shows your changes from last repoversion
svn diff -cX shows changes in version X
svn log [filename] shows all commit logs
Example: How to �nd a bug
1 You have been messing with the code
2 Suddenly you realized you broke the program
3 How do you �nd when was the bug introduced?
4 Hint: Can go back with svn update -rX
Investigating the past
svn diff shows your changes from last repoversion
svn diff -cX shows changes in version X
svn log [filename] shows all commit logs
Example: How to �nd a bug
1 You have been messing with the code
2 Suddenly you realized you broke the program
3 How do you �nd when was the bug introduced?
4 Hint: Can go back with svn update -rX
Advanced concepts: tags, branches, and merging
svn tag <name> [-rX] marks a version(e.g., release)
svn copy clones current version as branch
svn merge reintegrates branch to main trunk
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Trunks
Branches
Merges
Tags
Discontinueddevelopment
branch
CS 370, Günay (Emory) Version Control Spring 2014 9 / 15
Advanced concepts: tags, branches, and merging
svn tag <name> [-rX] marks a version(e.g., release)
svn copy clones current version as branch
svn merge reintegrates branch to main trunk
What is it good for?
Tags for beta test releases, main releases,patches
Branches for experimental development
See the SVN book for more info
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Trunks
Branches
Merges
Tags
Discontinueddevelopment
branch
CS 370, Günay (Emory) Version Control Spring 2014 9 / 15
Limitations of centralized version control
Tell me!
Obvious: it's centralized! Needs network for:
1 making commits2 getting updates3 inspecting revision history (logs, di�, etc)
What if you're coding on a plane?
I Enter distributed version control
CS 370, Günay (Emory) Version Control Spring 2014 10 / 15
Limitations of centralized version control
Tell me!
Obvious: it's centralized! Needs network for:
1 making commits2 getting updates3 inspecting revision history (logs, di�, etc)
What if you're coding on a plane?
I Enter distributed version control
CS 370, Günay (Emory) Version Control Spring 2014 10 / 15
Limitations of centralized version control
Tell me!
Obvious: it's centralized! Needs network for:
1 making commits2 getting updates3 inspecting revision history (logs, di�, etc)
What if you're coding on a plane?
I Enter distributed version control
CS 370, Günay (Emory) Version Control Spring 2014 10 / 15
Get your own repo!
Can do all VC operations locally now!
Thus you need to clone a repo
Get your own repo!
Can do all VC operations locally now!
Thus you need to clone a repo
So what is local and what is remote?
Local operations (same as previous):
update/commit
tag/branch
log/di�
Remote operations (new concepts):
Pull: Get all changesets fromorigin repo
Push: Send your changesets toorigin
Still has origin repo to communicate between team members
In Git, pull can be divided into fetch+merge (like SVN branch merge)
So what is local and what is remote?
Local operations (same as previous):
update/commit
tag/branch
log/di�
Remote operations (new concepts):
Pull: Get all changesets fromorigin repo
Push: Send your changesets toorigin
Still has origin repo to communicate between team members
In Git, pull can be divided into fetch+merge (like SVN branch merge)
So what is local and what is remote?
Local operations (same as previous):
update/commit
tag/branch
log/di�
Remote operations (new concepts):
Pull: Get all changesets fromorigin repo
Push: Send your changesets toorigin
Still has origin repo to communicate between team members
In Git, pull can be divided into fetch+merge (like SVN branch merge)
We will use Github
We have educational account with private repositories
Open accounts on GitHub and send us your account ids!
Example GitHub project
Git documentation: http://git-scm.com/documentation
History of version control software
Revision Control System (RCS):
Provided ci, co (checkin, checkout) commands underUNIX.Create revisions for each �le invidually
Concurrent Version System (CVS):
Like RCS, but systemic for directoriesCollects revision �les into repos
Subversion (SVN):
Allows renaming directories easilyRevisions not in �les, but kept in database
GIT:
Because somebody called Linus Torvald a git
Developed to keep track of changes in Linux kernel
Others:
Microsoft SourceSafe, Mercurial, . . .
CS 370, Günay (Emory) Version Control Spring 2014 15 / 15
