Subversion and Trac

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Subversion and Trac

• OOSE, Fall 2006
• Matthew Bolitho
• bolitho_at_cs.jhu.edu

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Source Control

• Also known as
• Version Control
• Revision Control
• The management of multiple revisions of the
  same unit of information Wikipedia

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Key Ideas

• Versioning
• Concurrency

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Versioning

• Store all revisions of a unit of information

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Versioning

• Store all revisions of a unit of information
• Time-shifting
• Can revert to an older version
• Can compare different versions

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Concurrency

• User A takes a copy of file X ? XA
• User B takes a copy of file X ? XB
• User A modifies XA ? XA
• User B modifies XB ? XB
• User A updates XA ? X
• User B updates XB ? X

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Concurrency

• User A takes a copy of file X ? XA
• User B takes a copy of file X ? XB
• User A modifies XA ? XA
• User B modifies XB ? XB
• User A updates XA ? X
• User B updates XB ? X

Update XA is lost!
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Concurrency

• How do we prevent lost updates?
• Locking
• Copy / Merge

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Locking

• User A obtains a lock for X
• User A takes a copy of X ? XA
• User A modifies XA ? XA
• User B tries to obtain a lock for X and fails
• User A updates XA ? X
• User A releases lock on X
• User B may now obtain a lock for X

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Copy / Merge

• User A takes a copy of X ? XA
• User A modifies XA ? XA
• User B takes a copy of X ? XB
• User A updates XA ? X
• User B modifies XB ? XB
• User B must merge X XB ? X

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Locking vs. Copy / Merge

• Locking
• Serializes all operations
• No need to merge
• Copy / Merge
• Merge operation is hard
• Maximum concurrency

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Subversion SVN

• Repository on server
• Working Copies on clients
• All groups will use SVN
• Server utrac.cs.jhu.edu

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Defining Terms

• Checkout The process of creating a new working
  copy
• Commit Sending changes made in a working copy,
  back into the repository
• Update Getting changes from the repository
  committed since you last updated the working copy

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Subversion Workflow
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Working Copy States

• A file in a working copy can be
• Unchanged and current
• Locally modified and current
• Unchanged and out-of-date
• Locally modified and out-of-date

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Branching

• Like to maintain concurrent branches of the
  same item
• Take a copy of X ? Y
• Now develop on both X and Y

Y
Y
Y
X
X
X
X
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Merging

• Have two branches with common ancestor
• Want to merge them back together

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Merging

• Each update is defined as a mutation

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Merging

• Each update is defined as a mutation
• Merging Y into X is applying all MY since Y was
  the same as X

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Tagging

• Tag a specific revision with a name

X
X
X
X
X
X
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Tagging

• Tag a specific revision with a name
• Example Tag a milestone

Iteration Two
Iteration One
X
X
X
X
X
X
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Trac

• Wiki
• Timeline
• Roadmap
• Source Browser
• Tickets

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Wiki

• Collaborative Documentation Tool
• Create a set of Topics
• Formatting expressed as plain text markup
• Can attach other files, and then like, eg images

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Wiki

• Collaborative Documentation Tool
• Create a set of Topics
• Formatting expressed as plain text markup
• Can attach other files, and then like, eg images

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Timeline

• Provides a historical summary of all edits,
  tickets, source changes

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Roadmap

• Allows a set of Milestones to be defined
• Milestones have a due date

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Roadmap

• Allows a set of Milestones to be defined
• Milestones have a due date

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Source Browser

• Provides a web-based, read-only interface into
  your source code
• Can view any version of source code
• Can compare between versions

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Source Browser

• Provides a web-based, read-only interface into
  your source code
• Can view any version of source code
• Can compare between versions

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Tickets

• Defines a task that needs to be completed
• Example Usage Use Case, Bug, etc.
• Can provide Description, Attach files (Wiki)
• Due Date, Milestone, Owner,

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Expectations

• ALL groups must use Trac and SVN
• Your grade will depend on how well you use Trac
  and SVN throughout the project
• We will use Trac exclusively to grade your
  projects

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Expectations

• Use Wiki for all project writeups, etc.
• We would like it if you would import your
  Iteration One and Two documents into Wiki format
• Use Milestones
• Should show Iteration Plan
• Use Tickets
• All Use Cases should be tickets
• All Bugs, Enhancements should be tickets

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Expectations

• We expect traceability Link information from one
  part of the SDLC to another
• Eg A bug fix ticket should refer to SVN
  changeset. http//trac.edgewall.org/wiki/TracLink
  s

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Expectations

• We expect traceability Link information from one
  part of the SDLC to another
• Eg A ticket should record the entire lifetime of
  a task. Record what was done to complete it,
  etc.

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Trac Installation

• Trac and SVN are already setup for you
• Trac http//utrac.cs.jhu.edu/groupN/trac
• SVN http//utrac.cs.jhu.edu/groupN/svn
• Need Login and Password will be emailed to you

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Subclipse

• Subversion plug-in for Eclipse
• http//subclipse.tigris.org/install.html

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Reading List

• http//svnbook.red-bean.com/en/1.1/index.html
• http//svn.collab.net/subclipse/help/index.jsp
• http//trac.edgewall.org/wiki/TracGuide