Intro to source control

1. > Source Control
> What you need to know.
Davey McGlade - Kainos

2. > Intro
• Solution Architect ~15 years experience
• In Kainos ~ 4 years
• Focus on:
• .NET
• Dynamics CRM 2011
• SharePoint 2010
• Integration technologies

3. > What is Source Control?
• In essence, a backup repository for your work.
• Two types:
• Centralised: All code on a central server
• Distributed: Everyone gets a copy locally
• Definitely not:
• Google Drive
• Drop Box
• C:
• Email.

4. > Why?
Recoverability Don’t lose work
Communication Easily see team changes
Versioning Compare and contrast
Accountability Who made the change?
Solve Problems Find bugs, try new things
Facilitate Reuse Avoid writing duplicate code

5. > Just code?
No
Anything and everything that is used to build the solution:
– Tools / Installers
– Solution Build Scripts
– Database Build scripts
– Some include Functional Specifications & Design Docs
Aids the transition into support.

6. > Terms
Trunk • The main ‘code line’. Contains the master code.
Branch • A deviation off the main code line.
Fork • Independent development on a copy from original
Commit • ‘Saving’ your code to the local/central repository
Push • Transfer changesets from the local to central
Pull • Retrieving changes from the central repository
Change set • The set of all delta changes
Merge • Combining your code changes with existing code
Tag • Marking a specific event, i.e. release 1.0 etc.

7. > Centralised
• A single ‘master’ copy of your code, held centrally on a server
• Changes are ‘committed’ to this central library.
• Once ‘committed’, other programmers can see the change.
• You can then ‘pull’ this change to your local machine.
• Examples of centralised source control systems
– CVS, Subversion (or SVN) Team Foundation Server, Visual
SourceSafe

8. > Workflow (Centralised)
1. Access the central server and ‘pull’ down the changes others
have made
2. Make your changes, and test them
3. Commit (*) your changes to the central server, so other
programmers can see them.
(*) Work out the merge conflicts (windiff, built in tools etc.)

9. > Example Workflows (Centralised)
• Branch by Release
V1.0 V1.1 V1.2
Release 1
Branch Merge
Release 2
V2.0 V2.1 V2.2
• Branch by Feature / Task
Feature 2 Branch Merge
Main Trunk
Branch Merge
Feature 1

10. > Distributed
• Each developer ‘clones’ a copy of a repository to their own
machine. The full history of the project is on their own hard
drive.
• Two phase commits: You commit first to your local staging
area, and then push to the repository.
• Central Repository is not mandatory, but you usually have one
• Examples of distributed source control systems
– Git, Mercurial, Bazaar

11. > Workflow (Distributed)
• Simple
Init/Clone Add Commit Push
• Branch by Member/ Features
V1.0 V1.1
Main Trunk
Development Trunk
Developer 1
Developer 2

12. > Is DVCS ‘better’?
• It’s extremely quick. No network traffic, only local file lookups.
• You remove the risk of poor networks. Centralised checkouts
typically aren’t atomic. Visual SourceSafe = nightmare.
• You can work locally, without affecting others. You can share work
amongst a select few, without pushing to the team.
• You can work offline, and merge your changes when you’re online
again.
• You have built in redundancy as the work is distributed amongst
team members.

13. > Git / Github demo
Demo Time

14. > Branching & Merging
Antipatterns
Some examples:
• Merge Paranoia—avoiding merging at all cost, usually because of a fear of the
consequences.
• Big Bang Merge—deferring branch merging to the end of the development effort
and attempting to merge all branches simultaneously.
• Never-Ending Merge—continuous merging activity because there is always more
to merge.
• Temporary Branches—branching for changing reasons, so the branch becomes a
permanent temporary workspace.
• Development Freeze—stopping all development activities while
branching, merging, and building new base lines.
Source - http://branchingguidance.codeplex.com/wikipage?title=Branching%20and%20Merging%20Anti-Patterns

15. > Taking it further
• Continuous Integration, Continuous Delivery
• Unit Testing
• Code Styling
• Performance Monitoring
• Broken Build fun
• Feature toggling – Martin Fowler,
http://martinfowler.com/bliki/FeatureToggle.html

16. > Tools
• GitHub & Git
– www.github.com
– http://git-scm.com/
• TortoiseSVN
– http://tortoisesvn.net/
• TortoiseGIT
– http://code.google.com/p/tortoisegit/wiki/Download
• Visual HG
– http://visualhg.codeplex.com/
• Git & SVN together
– http://infotexture.net/2010/02/git-to-svn-and-back-again/

17. > Learning Resources
• Git online interactive course
– http://try.github.com/levels/1/challenges/1
• Free Git Book
– http://git-scm.com/book
• Intro to SVN (Pluralsight Trial)
– http://pluralsight.com/training/Courses/TableOfContents/intro-to-svn
• Mercurial Intro
– http://hginit.com/
• Git to SVN course
– http://git.or.cz/course/svn.html

18. > Contact Details
• Web – daveymcglade.net
• Twitter – @djmcglade
• Slides – Will be up on slideshare / website