1. Systems Analysis and Design I
Session 11
Version Control

2. Version Control
A Version Control System (VCS) lets you track your files over time
Also known as
Revision Control
Source Control
(Source) Code Management 2

3. Why do you care?
Have you ever saved a file, and then wanted to revert the changes you made? Have you ever wished you could see what a file looked like some time ago?
Do you work in a team? Has it ever happened that you were working on a file, and someone else was working on the same file at the same time? Did you lose your changes to that file because of that?
Have you ever found a bug in your project and wanted to know when (and how) that bug got into your files?
--- Version Control with Subversion. 3

4. A Poor Man's Version Control System
A Poor Man’s VCS
Make a single backup copy (Document.bak).
If we’re clever, we add a version number or date: Document_V1.txt, DocumentMarch2019.txt
We may even use a shared folder so other people can see and edit files without sending them over . Hopefully they re-label the file after they save it.
Does this work for a large-scale development project? 4

5. Version Control Central (Client/Server) Model Distributed Model
Concurrent Versions System (CVS)
Apache Subversion (SVN) …
Distributed Model
Mercurial
Git 5

6. Client/Server Version Control System
--- Version Control with Subversion. 6

7. VCS: The Problem to Avoid
--- Version Control with Subversion. 7

8. VCS: Lock-Modify-Unlock Solution
--- Version Control with Subversion. 8

9. VCS: Copy-Modify-Merge Solution (1)
--- Version Control with Subversion. 9

10. VCS: Copy-Modify-Merge Solution (2)
--- Version Control with Subversion. 10

11. --- A Visual Guide to Version Control.

12. If you don’t like your changes and want to start over, you can revert to the previous version and start again (or stop).
When checking out, you get the latest revision by default. If you want, you can specify a particular revision
--- A Visual Guide to Version Control.

13. Most VCS store diffs rather than full copies of the file.
What’s the diff from r1 to r4?
--- A Visual Guide to Version Control.

14. Pretend you copied your code into a different directory
Branches let us copy code into a separate folder so we can monkey with it separately
Pretend you copied your code into a different directory
--- A Visual Guide to Version Control.

15. --- A Visual Guide to Version Control.

16. When changes overlap and contradict, the VCS may report a conflict and not let you check in — it’s up to you to check in a newer version that resolves this dilemma. 
--- A Visual Guide to Version Control.

17. 19

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