Common Revision Control Practices with Subversion

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Common Revision Control Practices with Subversion

• Inland Empire ColdFusion User Group
• Brian LeGros
• http//www.brianlegros.com/blog

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me

• Co-founder of the Adobe Developers of Greater
  Orlando (http//adogo.us)
• ColdFusion 7 years
• Flex/Actionscript 1 year
• Technical Lead for the Web Team at CFI

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terminology
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repository

• Administrable container for all Resources needing
  revisioning.

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repository - Subversion

• Stored in a Berkley DB or the file system
• Has hooks to execute scripts when an action
  occurs in the Repository (i.e. post-commit).
• File backups occur on the Repository level.
• Can be exposed via HTTP or SVN protocol.
• User authentication at Repository level.
• User authorization granular to the directory.

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resource

• Artifacts stored within the Repository, typically
  shown as directories and files.

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resource - Subversion

• Directories and files are used as Resources in a
  simple file system.
• Directories are separate resources from files
  even though they are containers for files.
• Files are identified as binary and non-binary
  which will determine how they are stored.

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project

• Grouping of like Resources contained within a
  Repository
• Usually multiple Projects per Repository

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project - Subversion

• No formal notion of a Project
• Project usually created as a named directory with
  the following structure

• project
• branches
• tags
• trunk

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revision

• A version number associated with a chain of
  changes to the contents of a single or multiple
  Resources in the Repository

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revision - Subversion

• project
• branches
• tags
• trunk
• src
• index.cfm

• Revision Snapshot of Repository

Revision 13

• project
• branches
• tags
• trunk
• src
• layout

• project
• branches
• tags
• trunk
• src
• layout
• index.cfm

Revision 15
Revision 14
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checkout

• To retrieve a Resource from the Repository to
  view and/or edit the Resource.

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checkout - Subversion

• Working copy
• Created when you checkout a directory and/or its
  contents from a Repository.
• Cannot checkout individual files.
• Contains hidden files on your file system which
  keep track of the changes you make on your local
  machine and how they differ from the latest
  Revision for a Resource in the Repository.

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check-in

• Saving the latest set of changes as a Revision
  for a single or group of Resources.
• Subversion Commit
• File/directory changes must be contained in a
  working copy to be detected

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HEAD

• Most recent Revision that a a group of Resources
  or an individual Resource was changed, added, or
  removed.
• Subversion
• HEAD is the last Revision of the Repository in
  which the file or directory was touched.

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HEAD

• project 105
• branches 100
• tags 100
• trunk 105
• src 105
• layout 101
• index.cfm 105

project HEAD 105, index.cfm HEAD 105,
branches HEAD 100
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trunk

• Unique line of development specific to a Project

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branch

• A unique line of development based on a copy of
  the Trunk or another Branch.

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tag

• A labeled snapshot of the Trunk, or a Branch, at
  a particular Revision.

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branch / tag - Subversion

• Copy Makes a copy of one directory into a newly
  named directory.
• Branches, Tags, Trunk are all directories with
  semantic meaning
• Copy command in some clients will add metadata
  showing the intent of the copy

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merge

• Process of integrating the change set associated
  with a Branch into another Branch or the Trunk.

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merge - Subversion

• 2 step process
• Build change set from Branch needing integration
  (svn diff)
• Integrate change set into Branch or Trunk (apply
  svn diff to working copy)

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patch

• Process of creating an artifact representative of
  the change set associated with a Branch or the
  Trunk.

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patch - Subversion

• 1st step of the merge process placed into a file
  external to the Repository.
• Can only work on non-binary files.

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take a look at Subversion
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concurrency models
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what?

• Control mechanisms for concurrently editing
  Resources in the Repository

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lock / edit / watch
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Basic Flow
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Basic Flow
2. Checkout
1. Checkout
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Basic Flow
2. Checkout

• 1. Checkout
• Lock
• 4. Edit

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Basic Flow
2. Checkout 5. Lock

• 1. Checkout
• Lock
• 4. Edit

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Basic Flow
2. Checkout 5. Lock 6. Watch

• 1. Checkout
• Lock
• 4. Edit

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Basic Flow
2. Checkout 5. Lock 6. Watch

• 1. Checkout
• Lock
• 4. Edit
• 7. Check-in
• 8. Unlock

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Basic Flow
2. Checkout 5. Lock 6. Watch 9. Notify

• 1. Checkout
• Lock
• 4. Edit
• 7. Commit
• 8. Unlock

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Basic Flow
2. Checkout 5. Lock 6. Watch 9. Notify 10.
Lock 11. Rinse/Repeat

• 1. Checkout
• Lock
• 4. Edit
• 7. Commit
• 8. Unlock

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Alternative Flow - Highjack
2. Checkout 5. Lock

• 1. Checkout
• Lock
• 4. Edit

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Alternative Flow - Highjack
2. Checkout 5. Lock 6. Hijack

• 1. Checkout
• Lock
• 4. Edit

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Alternative Flow - Highjack
2. Checkout 5. Lock 6. Hijack 7. Edit

• 1. Checkout
• Lock
• 4. Edit

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Alternative Flow - Highjack
2. Checkout 5. Lock 6. Hijack 7. Edit

• 1. Checkout
• Lock
• 4. Edit
• 8. Check-in

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Alternative Flow - Highjack
2. Checkout 5. Lock 6. Hijack 7. Edit

• 1. Checkout
• Lock
• 4. Edit
• 8. Check-in
• 9. Watch

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lock / edit / watch

• Benefits
• No conflict resolution needed
• Small learning curve
• Challenges
• Sequential development creep
• Managing hijackers

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checkout / update / check-in
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Basic Flow
45
Basic Flow
3. Checkout 4. Edit
1. Checkout 2. Edit
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Basic Flow
3. Checkout 4. Edit
1. Checkout 2. Edit 3. Update
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Basic Flow
3. Checkout 4. Edit
1. Checkout 2. Edit 3. Update 4. Check-in
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Basic Flow
3. Checkout 4. Edit 6. Update
1. Checkout 2. Edit 3. Update 5. Check-in
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Basic Flow
3. Checkout 4. Edit 6. Update 7. Resolve
1. Checkout 2. Edit 3. Update 5. Check-in
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Basic Flow
3. Checkout 4. Edit 6. Update 7. Resolve 8.
Check-in
1. Checkout 2. Edit 3. Update 5. Check-in
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Alternate Flow - Overwrite
3. Checkout 4. Edit 6. Update
1. Checkout 2. Edit 3. Update 5. Check-in
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Alternate Flow - Overwrite
3. Checkout 4. Edit 6. Update 7. Ignore
1. Checkout 2. Edit 3. Update 5. Check-in
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Alternate Flow - Overwrite
3. Checkout 4. Edit 6. Update 7. Ignore 8.
Check-in
1. Checkout 2. Edit 3. Update 5. Check-in
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checkout / update / check-in

• Benefits
• Concurrent development
• Project management friendly
• Challenges
• Integrity of potentially complex conflict
  resolutions
• Potentially difficult learning curve

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branching strategies
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what?

• Patterns that teams of developers can use to
  coordinate concurrent development efforts.

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unstable trunk
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unstable trunk
Trunk
Time
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unstable trunk
Feature 1,2, and 3
Trunk
Time
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unstable trunk
Release 1.0
Branch/Tag
Feature 1,2, and 3
Trunk
Time
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unstable trunk
Fix 1
Release 1.0
Merge
Feature 1,2, and 3
Trunk
Time
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unstable trunk
Fix 1
Release 1.0
Feature 1,2, and 3
Feature 4
Trunk
Time
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unstable trunk
Fix 1
Fix 2
Release 1.0
Merge
Feature 1,2, and 3
Feature 4
Trunk
Time
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unstable trunk
Release 1.1
Branch / Tag
Fix 1
Fix 2
Release 1.0
Feature 1,2, and 3
Feature 4
Trunk
Time
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unstable trunk
Release 1.1
Fix 1
Fix 2
Release 1.0
Feature 1,2, and 3
Feature 4
Feature 5
Trunk
Time
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unstable trunk
Release 1.1
Fix 1
Fix 2
Release 1.0
Release 2.0
Branch / Tag
Feature 1,2, and 3
Feature 4
Feature 5
Trunk
Time
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unstable trunk

• Benefits
• Simple administration
• Small learning curve
• Challenges
• Encourages a sequential release process
• Potential difficulty coordinating large of
  developers
• Release planning required

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stable trunk
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stable trunk
Trunk
Time
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stable trunk
Branch 1
Branch
Trunk
Time
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stable trunk
Feature 1, 2, and 3
Branch 1
Trunk
Time
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stable trunk
Feature 1, 2, and 3
Branch 1
Trunk
Branch
Branch 2
Time
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stable trunk
Feature 1, 2, and 3
Branch 1
Trunk
Feature 4
Branch 2
Time
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stable trunk
Feature 1, 2, and 3
Branch 1
Merge
Trunk
Feature 4
Branch 2
Time
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stable trunk
Feature 1, 2, and 3
Branch 1
Release 1.0
Tag
Trunk
Feature 4
Branch 2
Time
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stable trunk
Feature 1, 2, and 3
Fix 1
Branch 1
Release 1.0
Trunk
Feature 4
Branch 2
Time
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stable trunk
Feature 1, 2, and 3
Fix 1
Branch 1
Release 1.0
Trunk
Feature 4
Feature 5
Branch 2
Time
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stable trunk
Feature 1, 2, and 3
Fix 1
Fix 2
Branch 1
Release 1.0
Trunk
Feature 4
Feature 5
Branch 2
Time
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stable trunk
Feature 1, 2, and 3
Fix 1
Fix 2
Branch 1
Release 1.0
Merge
Trunk
Feature 4
Feature 5
Branch 2
Time
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stable trunk
Feature 1, 2, and 3
Fix 1
Fix 2
Branch 1
Release 1.0
Release 1.1
Tag
Trunk
Feature 4
Feature 5
Branch 2
Time
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stable trunk
Feature 1, 2, and 3
Fix 1
Fix 2
Branch 1
Release 1.0
Release 1.1
Trunk
Merge
Feature 4
Feature 5
Branch 2
Time
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stable trunk
Feature 1, 2, and 3
Fix 1
Fix 2
Branch 1
Release 1.0
Release 1.1
Trunk
Merge
Feature 4
Feature 5
Branch 2
Time
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stable trunk
Feature 1, 2, and 3
Fix 1
Fix 2
Branch 1
Release 1.0
Release 1.1
Release 2.0
Tag
Trunk
Feature 4
Feature 5
Branch 2
Time
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stable trunk

• Benefits
• Parallel releases
• Large team friendly
• Challenges
• High administration costs
• Larger learning curve than unstable trunk
• Release planning required

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promotional strategies
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what?

• Using snapshots of a code base to create
  artifacts that correlate to a software
  development lifecycle.

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common sdlc
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agile promotion
Trunk
Time
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agile promotion
Branch 1
Branch
Trunk
Time
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agile promotion
Feature 1
Branch 1
Trunk
Time
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agile promotion
Feature 1
Branch 1
Branch 2
Branch
Trunk
Time
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agile promotion
Feature 1
Branch 1
Feature 2
Branch 2
Trunk
Time
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agile promotion
Feature 1
Branch 1
Feature 2
Branch 2
Trunk
Branch
Branch 4
Time
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agile promotion
Feature 1
Branch 1
Feature 2
Branch 2
Branch 3
Branch
Trunk
Branch 4
Time
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agile promotion
Feature 1
Branch 1
Feature 2
Branch 2
Feature 3
Branch 3
Trunk
Branch 4
Time
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agile promotion
Feature 1
Branch 1
Feature 2
Branch 2
Merge
Feature 3
Branch 3
Trunk
Branch 4
Time
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agile promotion
Feature 1
Branch 1
Test 1
Feature 2
Branch 2
Feature 3
Branch 3
Tag
Trunk
Branch 4
Time
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agile promotion
Feature 1
Branch 1
Test 1
Feature 2
Branch 2
Test 2
Feature 3
Branch 3
Tag
Trunk
Branch 4
Time
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agile promotion
Feature 1
Branch 1
Test 1
Feature 2
Branch 2
Test 2
Feature 3
Branch 3
Trunk
Merge
Branch 4
Time
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agile promotion
Feature 1
Branch 1
Test 1
Feature 2
Branch 2
Test 2
Release 1.0
Feature 3
Branch 3
Tag
Trunk
Branch 4
Time
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agile promotion
Feature 1
Branch 1
Test 1
Feature 2
Branch 2
Test 2
Release 1.0
Feature 3
Branch 3
Trunk
Fix 1
Branch 4
Time
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agile promotion
Feature 1
Branch 1
Test 1
Feature 2
Branch 2
Test 2
Release 1.0
Feature 3
Branch 3
Trunk
Fix 1
Fix 2
Branch 4
Time
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agile promtion

• Benefits
• Artifacts to pair with SDLC stages for auditing
• Easier for non-developers to work with snapshots
  (i.e. deployers, reviewers, etc.)
• No release planning necessary
• Challenges
• Requires adherence to an SDLC
• Potentially large administration costs (e.g. -
  tag clean up)

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references

• SVN Online Book - http//svnbook.red-bean.com/
• Wikipedia Revision control - http//en.wikipedia
  .org/wiki/Scm
• CollabNet SVN 1.5 Branching Preso -
  http//www.collab.net/webinar21/

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thanks