This document provides an overview of Subversion, an open-source version control system. It describes Subversion's fundamental concepts like repositories, versioning models using copy-modify-merge, and basic usage such as checking out, updating, committing changes. It also covers topics like properties, locking, branching and merging, best practices, and server configurations. The document aims to explain Subversion's capabilities and how it can be used to track changes to files and work collaboratively on projects.

1. Version Control with
Subversion
PLUG Linux Users Group
Senthil_OR@Dell.com
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2. Subversion
In the world of open-source software, the Concurrent Versions
System (CVS) was the tool of choice for version control for many
years.
Subversion is similar to CVS, but it avoids most of CVS
noticeable flaws.
The most common use for Subversion is to track changes to
source code. But Subversion can be used to manage changes to
any sort of information—images, music, databases,
documentation, and so on. To Subversion, all data is just data.
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3. What is Subversion?
Subversion is a free/open-source version
control system. Subversion manages files
and directories, and the changes made to
them, over time. This allows you to recover
older versions of your data, or examine the
history of how your data changed.
Fosters Collaboration.
Mistakes can be undone.
Is NOT a Software Configuration
Management system. Version control of any
data, perhaps your telephone bills. ?
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4. Subversion provides
Directory versioning.
True version history.
Atomic commits
Versioned metadata.
Choice of Network Layers.
Consistent Data Handling.
Efficient Branching and Tagging
Hackablity
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5. Fundamental Concepts
The kind of a file server.
Repository
Repository is
What makes it special is that it remembers every change ever
written to it: every change to every file, and even changes to the
directory tree itself, such as the addition, deletion, and
rearrangement of files and directories.
When a client reads data from the repository, it normally sees
only the latest version of the filesystem tree. But the client also
has the ability to view previous states of the filesystem. For
example, a client can ask historical questions like, “What did this
directory contain last Wednesday?”
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6. Fundamental Concepts:
Versioning Models
The problem of file sharing:
Problem to Avoid!
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7. Fundamental Concepts: Versioning Models:
The Lock-Modify-Unlock Solution
In this Model, Repository
allows only one person to
change at a time.
Locking may cause
Administrative Problems
Locking may cause
unnecessary serialization.
Locking may create a false
sense of security.
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8. Fundamental Concepts: Versioning Models:
The Copy-Modify-Merge Solution
In this model, each user's client contacts the project
repository and creates a personal working copy—a
local reflection of the repository's files and
directories.
Users then work simultaneously and independently,
modifying their private copies. Finally, the private
copies are merged together into a new, final version.
The version control system often assists with the
merging, but ultimately a human being is
responsible for making it happen correctly.
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9. Fundamental Concepts: Versioning Models:
The Copy-Modify-Merge Solution
Figure 1:
Figure 2:
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10. Fundamental Concepts: Versioning Models:
The Copy-Modify-Merge Solution
What if changes do overlap? This situation is called a conflict,
and it's usually not much of a problem
When Harry asks his client to merge the latest repository
changes into his working copy, his copy of file A is somehow
flagged as being in a state of conflict: he'll be able to see both
sets of conflicting changes, and manually choose between them.
Note that software can't automatically resolve conflicts; only
humans are capable of understanding and making the necessary
intelligent choices. Once Harry has manually resolved the
overlapping changes—perhaps after a discussion with Sally—he
can safely save the merged file back to the repository.
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11. Fundamental Concepts: Versioning Models:
The Copy-Modify-Merge Solution
The copy-modify-merge model may sound a bit chaotic, but in
practice, it runs extremely smoothly.
Users can work in parallel, never waiting for one another
When they work on the same files, it turns out that most of their
concurrent changes don't overlap at all; conflicts are infrequent.
And the amount of time it takes to resolve conflicts is usually far
less than the time lost by a locking system.
In the end, it all comes down to one critical factor: user
communication. When users communicate poorly, both syntactic
and semantic conflicts increase. No system can force users to
communicate perfectly, and no system can detect semantic
conflicts
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12. Fundamental Concepts:
Subversion in Action.
Subversion Repository URLs.
svn checkout http://svn.example.com:9834/repos
svn checkout file:///path/to/repos
Working Copies.
.svn directory in the working copy contains administrative files.
To get a working copy, you checkout from the repository:
$ svn checkout http://svn.example.com/repos/calc
A calc/Makefile
A calc/integer.c
A calc/button.c
Checked out revision 56.
$ ls -A calc
Makefile integer.c button.c .svn/
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13. Fundamental Concepts:
Subversion in Action
The act of publishing your changes is more
commonly known as committing (or checking
in) changes to the repository.
$svn commit filename –m “log”
#collaborator will do:
#svn update
$svn commit operation publishes changes to
the any number of files and directories as a
single atomic transaction.
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14. Fundamental Concepts:
Subversion in Action
Repository Structure.
Single Global Revision.
Unlike most version
control systems,
Subversion's revision
numbers apply to entire
trees, not individual
files
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The Repository
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15. Fundamental Concepts:
Subversion in Action
Inside .svn directory keeps track as files
working revision and timestamp of update.
Unchanged, and Current.
Locally Changed, and Current.
Unchanged and Out of date
Locally Changed and Out of date.
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16. Basic Usage
Getting data into Repository – svn import
Recommended Repository layout.
/trunk
/branches
/tags
Initial checkout: svn checkout repopath
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17. Basic Work Cycle
Update your woking copy.
svn update
Make changes.
svn add
svn delete
svn copy
svn move
Examine your changes
svn status
svn diff
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18. Basic Work Cycle
Possibly undo some changes.
svn revert
Resolve Conflicts ( Merge others changes)
svn update
svn resolved
Commit your changes.
svn commit
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19. Examining History
svn log
svn diff
svn cat
svn list
svn cleanup
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20. Revision Specifiers
HEAD
The latest (or “youngest”) revision in the repository.
BASE
The revision number of an item in a working copy. If the item has
been locally modified, the “BASE version” refers to the way the
item appears without those local modifications
COMMITTED
The most recent revision prior to, or equal to, BASE, in which an
item changed.
PREV
The revision immediately before the last revision in which an item
changed. Technically, this boils down to COMMITTED-1.
Revision Dates
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21. Properties
In addition to versioning your directories and files,
Subversion provides interfaces for adding,
modifying, and removing versioned metadata on
each of your versioned directories and files. We
refer to this metadata as properties.
Custom revision properties are also frequently used.
One common such use is a property whose value
contains an issue tracker ID with which the revision
is associated, perhaps because the change made in
that revision fixes a bug filed in the tracker issue
with that ID.
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22. Property setting
svn propset license -F /path/to/LICENSE
calc/button.c property 'license' set on
'calc/button.c'
svn:eol-style
svn:executable
svn:keywords
svn:mime-type
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23. Keyword substitution
Subversion has the ability to substitute
keywords—pieces of useful, dynamic
information about a versioned file—into the
contents of the file itself
Date, Revision, Author, HeadURL, Id
Set the svn:keyword property of any of the
above
Use the $Date$, $Author$ notation in the
versioned file. The values will get
automatically substituted.
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24. Locking
Locking concept supported by svn.
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25. Branching and Merging
Branches are svn copy
operation on the
Repository.
Branches of Development
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26. Branching and Merging
After Branching
Start point
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27. Best practises of merging
Tracking Changes Manually.
Previewing merges.
Noticing and ignoring ancestry
Merges and Moves
Creating a Tag, same as Branch
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28. SVN Server configuration
Svnserve Server
Svnserve over ssh
The Apache HTTP server
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29. Comparision of the Repositories
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30. That’s all Folks
Lundblad is a leading
contributor to the
Subversion open source
code project, which has
produced a widely
implemented code
management system. He
was among five leaders of
open source code
recognized in August at the
O'Reilly Open Source
Conference. Unlike the
others, Lundblad is blind.
Amazing!
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