Corporate Adoption of Distributed Version Control

Slides from my talk at GLSEC 2013.

Transcript

1. Corporate Adoption of Distributed Version Control @JaceBrowning
2. Why are we on this topic? If your company is not in the process of exploring distributed version control, they should start.
3. Major Advantages #1 Collaboration #2 Branching #3 Efficiency #4 Productivity #5 Scalability #6 Affordability Change what you mean to change but keep separate changes separate to work as fast as possible without barriers for any of your teammates without killing your budget.
4. But first, some background...
5. So, what is version control? Storage of all changes Their ownership And explanation What? Who? Why?
6. What version control isn’t. Backup Access Control Workflow Management Metrics Collection Etc. You typically get these things, but that’s not the point.
7. A Brief History Three Generations: Local Networked (Centralized) Decentralized (Distributed) No longer used. (I hope) Status quo for corporations. Adopted for open source, web, and mobile development.
8. Centralized Version Control Systems
9. History Early 1990s Desire for collaboration incorporated the network But, a new architecture was needed 㱺 CVCS
10. Centralized Storage Unit: file revisions Storage: linear histories Repository: central server 1 2
11. Centralized Workflow 1 1 1 2 2 Baseline (File Revision) 2.1
12. Centralized Examples Concurrent Versions Systems (CVS) Apache Subversion (SVN) IBM Rational ClearCase Perforce Microsoft Visual SourceSafe (VSS) Serena Dimensions 2000 1990
13. Distributed Version Control Systems
14. History Mid 2000s Desire for global collaboration added replication But, a new architecture was needed 㱺 DVCS
15. Distributed Storage Unit: changesets Storage: DAG Repository: all computers 2:05a1da06de90f47... 1:c08d9939d76af4e7...
16. Distributed Workflow Tag 2:05a1da06de90f47... (Changeset) 3:17e465a3b4a13a6... 1:c08d9939d76af4e7... 4:076932b4a7c7160...
17. Distributed Tool Examples 2010 2005 Veracity Git Mercurial Bazaar Fossil
18. Distributed Advantages #1 Collaboration #2 Branching #3 Efficiency #4 Productivity #5 Scalability #6 Affordability Change what you mean to change but keep separate changes separate to work as fast as possible without barriers for any of your teammates without killing your budget.
19. #1 Collaboration
20. One Developer 1. Get code 2. Make changes 3. Share them No issues here.
21. But, Multiple Developers 1. Get code 2. Make changes 3. Share them 1. Get code 2. Make changes 3. Share them Problem?
22. CVCS Example 1 1 1 2 2 1 1 1 2 2 Developer A Developer B
23. CVCS Example 1 1 1 2 2 3 2 Developer A’s Change Developer A+B’s Change
24. DVCS Example 1 1 1 2 2 1 1 1 2 2 Developer A Developer B
25. DVCS Example 2:05a1da06de90f47... 3:17e465a3b4a13a6... 4:076932b4a7c7160... 1 1 1 1:c08d9939d76af4e7...
26. #2 Branching
27. Separate Changes When to branch: For releases For features For bug fixes For everything!
28. CVCS Example 1 1 1 2 2 2 1.1 2.1 3 2 2.1 3 1.2
29. DVCS Example 2:05a1da06de90f47... 3:17e465a3b4a13a6... 4:076932b4a7c7160... 5:f55eeed54787979... 1:c08d9939d76af4e7...
30. #3 Efficiency
31. Minimizing Overhead Most actions require access to the repository: Getting code Adding files Removing files Renaming files Saving changes Tagging baselines Comparing tags Creating branches Merging branches Etc.
32. CVCS Example Repository Intranet or Internet Update Add+Remove / Tag Compare / Merge Code Commit
33. DVCS Example Intranet or Internet Update Add+Remove / Tag Compare / Merge Commit Repository Repository Code Sync
34. #4 Productivity
35. CVCS Example Causes of Downtime: Server upgrades or crashes Network connectivity loss Customer/supplier site network access Travel, home, etc.
36. DVCS Example During Downtime: Nearly all operations are available Effective merging means swift recovery Code is also implicitly backed up on every computer
37. #5 Scaleability
38. CVCS Example Options: 1. Get a bigger server (scale up) Impact: Downtime Non-linear cost growth $ $$ $$$
39. Options: 1. Get a bigger server (scale up) 2. Scale out DVCS Example $ $ $ $ $ $ $ $ $ $ $ $
40. #6 Affordability
41. CVCS Example 100 Developers and 50 Projects Fixed License Cost: $4125, $2930, $3520, $1880 $2000 × 100 Developers = $200k
42. DVCS Example Free Local Hosting Scalable Cloud Hosting: $20/developer/month $200k ÷ (100 developers × $20/month) = 8+ years
43. Summary
44. Distributed > Centralized Atomic storage of logical changes Local history is branch and merge friendly Efficient synchronization between repositories Limited hardware and network dependencies Flexible network architecture and scalability Cost-effective hosting options
45. So, what’s next? Free Downloads: Git, Mercurial, Veracity, etc. Gradual Exploration: Tools + Scripts 㱺 Tests 㱺 New Projects Cloud Hosting and Communities: GitHub, SourceForge, Bitbucket, onVeracity, etc.
46. Questions?