Version Control

With Mercurial and Progress

Introduction What is version control ? Why use version control ? Centralised vs. Distributed Why Mercurial ? Using Mercurial [with Progress]

Examples / Demos Questions

Overview

Julian Lyndon-Smith, dot.r limited Progress developer since v3 Fan of vcs since 1987 Developed, sold Boss (Progress-based vcs) Other vcs systems used include

Roundtable ~1992-1994 SourceSafe ~1994-1998 Cvs ~1998-2004 Subversion ~2004-2011

Introduction

As developers, we write code that changes

over time Bugs

aka “feature” aka “undocumented behaviour” aka “works on my machine”

New functionality Aka “we could charge for this”

Better way of doing something aka “I want to play with this cool new tech”

What is version control?

Everyone uses a version control system

Just not the right one Copy foo.p foo.[x].p (where x=1 to … ) Modify foo.p

What is version control?

Audit trail of changes

Who did what, where, why and when ? Syncronization

Share the same code between developers Backup

Get any version of the file from any time Revert

Throw away local changes

Why use version control?

Centralised vcs

checkout checkin

checkin checko

ut

checkin checko

ut

Centralised vcs

Centralized version control systems Cvs Source safe Rcs Subversion

Single central copy of project / source (aka “repo”)

Committing records changes into central repo Other developers see this change

Centralised vcs

Workflow Pull changes from central repo Make changes Commit changes back to central repo

Disadvantages Only “latest” copy of source available Need to be online / connected All changes to a file have to be in one

changeset

Strengths

Workflow is familiar to most developers Only one place for all source Trunk has latest version

Weaknesses

Poor merging No offline commits Any commit is available to all users

Working or not Breaks build servers Days or weeks between checkins

Commits only apply to selected subdirectory and children (subversion)

Distributed vcs

checkout checkin

checkout checkin

checkin checko

ut

checkin checko

ut

QA Repo Build Repo

Distributed vcs

Distributed version control systems Mercurial Git Arcs Bazaar

Multiple copies of all versions of project / source

Committing records changes into local repo Other developers do not see this change Until pushed back to remote repo

Distributed vcs

Workflow Clone repo Make changes Commit changes back to own repo Push changes up to remote repo

Disadvantages None …

Strengths

All repositories are equal Offline history Offline commit Less chance of merge conflicts “hidden” experimental branches

Weaknesses

Who has the “latest” version ? Large Binary files

Fixed in later releases Mindset

Why mercurial ?

Boiled down to git or mercurial Git

Poor documentation Complicated command lines Gui for eclipse did not work for me

Mercurial Worked first time Gui worked first time

Purely personal choice.

Using mercurial

The basics

Using mercurial

Download from http://http://mercurial.selenic.com/

Update settings

Using mercurial

Download from http://http://mercurial.selenic.com/

Go to your source code directory hg init

There’s now a .hg directory Now “add” the source files to the repository

hg add Now commit the files to the repository

hg commit

Using mercurial

So, what happened in the repository ? hg log

Shows the history of changes User, notes, changeset id and date In reverse order (latest first)

Let’s make a change to a file (h-BinCheck.p) And commit it

hg commit

Using mercurial

Let’s see the log now hg log

What were the changes ? hg diff –r0:1 h-BinCheck.p

Let’s make more changes What is the status of my working directory ?

hg status What were the changes ?

hg diff

Using mercurial

Don’t like what you see ? hg revert (creates .orig file) hg revert –no-backup (no .orig file)

Mercurial Repositories

checkout checkin

checkout checkin

checkin checko

ut

checkin checko

ut

QA Repo Build Repo

Mercurial Repositories

A “Central” repository is useful for Providing a master repo for QA Providing a convenient repo for cloning

Hg serve Starts a webserver on port 8000 Allows a repo to be accessed by other

developers Server or developer machine Generally LAN only

Mercurial Repositories

Bitbucket http://bitbucket.org/ Free for up to 5 users Built-in issue tracking Unlimited repositories (private / public) Available wherever there is an internet

connection Demo: Create a new repository (pugus)

Creates a repository from another repository

hg clone https://bitbucket.org/jmls/pugus pugus Inits the repo Downloads the entire repository Updates the working directory

Add a new file, commit hg add hg commit

Cloning

Repository changesets

n/a

• [empty repository]

Repo @ bitbucket

0

• My initial version

Repo @ my computer

Pushing changes

Now we need to push changes up to remote repo hg push

Rinse, repeat make another change “added comments” commit, push

0

• My initial version

Repo @ bitbucket

0

• My initial version

Repo @ my computer

Pushing changes

Now we have hg push

1• Added comments

0• My initial version

Repo @ bitbucket

1• Added comments

0• My initial version

Repo @ my computer

Another developer ..

Alice has been added to the dev team Needs to clone the repository

hg clone

1• Added comments

0• My initial version

Repo @ bitbucket

1• Added comments

0• My initial version

Repo @ Alice

1• Added comments

0• My initial version

Repo @ my computer

Multiple changes

I add a new file Alice modifies readme.txt Both commit

2• Added install.txt

1• Added comments

0• My initial version

Repo @ my computer

2

• Added copyright message

1• Added comments

0• My initial version

Repo @ Alice

Alice pushes

Alice pushes to remote repo

2

• Added copyright message

1• Added comments

0• My initial version

Repo @ bitbucket

2

• Added copyright message

1• Added comments

0• My initial version

Repo @ Alice

I push

I push to remote repo Fails.

I need to get the updated changesets before I can push hg incoming

Shows all changes hg pull

Now there are 2 heads (mine and Alice’s) Working directory not updated

I push

Merge the two heads hg merge Updates working directory hg commit hg push

Alice doesn’t have the latest version

I push

4• merged changesets

3• Added install.txt

2• Added copyright message

1• Added comments

0• My initial version

Repo @ bitbucket4

• Merged changesets

3• Added copyright message

2• Added install.txt

1• Added comments

0• My initial version

Repo @ my computer

2

• Added copyright message

1• Added comments

0• My initial version

Repo @ Alice

Alice doesn’t have the latest version hg pull

No merge needed, just update hg update

Alice now has the latest version of the repository

Alice pulls

4• Merged changesets

3• Added install.txt

2• Added copyright message

1• Added comments

0• My initial version

Repo @ alice

General workflow

pull

update

Make change

s

commit

PullMerge

Test

Commit

push

Workbench demo

Help => Install new Software

Mercurial Eclipse

Create new Progress project

File => New=>Other

Mercurial Eclipse

To create a Progress view on the project

Select Project Properties Select Project Facets Select Openedge / GUI for .net Apply

Now we have a progress project with a mercurial team No more command line ;)

Mercurial Eclipse

Demos, Questions,Debate