Effective Development with... Eclipse, Mylyn, Git, Gerrit and Hudson (Jenkins) Chris Aniszczyk (Red Hat) Principal Software Engineer zx@redhat.com http://aniszczyk.org

About Me Hack on Eclipse, OSGi, Git and other things at Red Hat Member of the Eclipse Board of Directors Member in the Eclipse Architecture Council I like to run! (2 minutes over of Boston qualifying ;/) Co-author of RCP Book (www.eclipsercp.org) Starting a new book on Git and Gerrit... Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

Introduction - Mylyn Reloaded Hudson (Jenkins) and Mylyn Distributed Version Control (DVCS) Code Review with Git, Gerrit and Mylyn Conclusion Q&A Agenda Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

What is Mylyn? Mylyn is the task and application lifecycle management (ALM) framework for Eclipse. It provides... The task-focused interface that realigns the IDE around tasks so that you see only the code that's relevant A task management tool for developers A broad ecosystem of Agile and ALM integrations. There are dozens of extensions integrate Mylyn with ALM and developer collaboration tools Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

Mylyn Integrates within the IDE Mylyn reduces context switching... Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

Mylyn History 2004: Task-focused interface ideas on UBC whiteboard 2006: v1.0, early adopters help evolve the UI 2007: v2.0, API grows from integration needs, increasing 2008: v3.0, API solidifies, extensions increase 2009: v3.3, de facto ALM integration for Eclipse, dozens of extensions 2010: Expansion of participation and new project creation 2011: Mylyn 3.5 Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

Mylyn 3.4 Tasks Bugzilla Trac OSLC Context Versions Docs Java C/C++ CVS WikiText Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

Mylyn 3.5 – Restructured Tasks Bugzilla Trac OSLC Context Reviews Builds Versions Docs Java C/C++ CVS Git Hudson WikiText RichText OSLC OSLC IEEE Tasks Gerrit Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

Introduction Hudson (Jenkins) and Mylyn - What is Hudson (Jenkins) - Mylyn Builds The Rise of Distributed Version Control (DVCS) Code Review with Git, Gerrit and Mylyn Conclusion Q&A Agenda Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

What is Hudson (Jenkins)? Hudson is an extensible continuous integration server Easy to use Tons of plug-ins Very popular within the Java community Recently forked by the community via Jenkins Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

Mylyn Builds “The scope of the Mylyn Builds project is integration of continuous integration and build systems (eg., Hudson) within Eclipse. In addition to the seamless access to software build and assembly technologies. Mylyn users will be able to access continuous integration processes, control build execution and associate build results with tasks and context.” http://eclipse.org/mylyn/builds You'll find yourself leaving Eclipse less! Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

Mylyn Builds Demo Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

Introduction Hudson (Jenkins) and Mylyn Distributed Version Control (DVCS) - Why DVCS? Why Git? - Lessons learned at Eclipse moving to Git - Mylyn Versions and EGit Code Review with Git, Gerrit and Mylyn Conclusion Q&A Agenda Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

Version Control Version Control Systems manage change “The only constant is change” (Heraclitus) Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

Why Version Control? VCS became essential to software development because: They allow teams to collaborate They manage change and allow for inspection They track ownership They track evolution of changes They allow for branching They allow for continuous integration Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

“Hey, get back to work!” … “My code's merging” - remember those days you spent merging in changes in CVS/SVN? Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

Version Control: The Distributed Every client has a copy of the full repository locally All repository operations are local (except sharing) Intelligent network operations when sharing content A very non linear revision history Large online communities to share changes Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

Software Trends and Revolution Most major open source projects use some form of DVCS Git, Hg, Bazaar Linux MySQL OpenJDK Android JQuery Gnome Fedora Bugzilla and so on... But why? Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

Benefits of Distributed Version Control Can collaborate without a central authority Disconnected operations Easy branching and merging Define your own workflow Powerful community sharing tools Easier path to contributor to committer Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

Collaboration Developers can easily collaborate directly without needing a central authority or dealing with server administration costs Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

Disconnected operations rule! Developers can still be productive and not worry about a central server going down... remember the days of complaining that CVS was down and you couldn't work? Also, there's a lighter server load for administrators! Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

Branches everywhere Creating and destroying branches are simple operations so it's easy to experiment with new ideas Very easy to isolate changes Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

Define your own workflow Define your own workflow to meet your team needs. Different workflows can be adopted as your team grows without changing VCS toolsets! Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

DVCS and Building Community Developers can easily discover and fork projects. On top of that, it's simple for developers to share their changes “Distributed version control is all about empowering your community, and the people who might join your community” - Mark Shuttleworth Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

Version Control at Eclipse Eclipse defined a roadmap to move to Git in 2009 CVS/SVN are deprecated now Each project is moving to Git on its own timeline... So why did Eclipse.org choose Git? Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

#1: Git-related projects at Eclipse.org … both the core Git library (JGit) and tooling (EGit) are actively developed at Eclipse.org by a diverse set of committers and contributors with a common goal Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

#2: Git is fast … Git is fast and scales well *whyisgitbetterthanx.com Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

#3: Git is mature and popular … Git is widely used and is the most popular distributed version control system Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

#4: Git community tools … interested in taking advantage of such Git tools like Gerrit Code Review (used by the Android community) and GitHub Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

Convincing management and peers was tough - At first, everyone is resistant to change The learning curve of DVCS systems is high - Initially, the Eclipse tooling was “alpha” - People refuse to drop to the CLI Legacy is a pain in the ass! - 200+ projects at Eclipse used CVS/SVN - The existing VCS tooling was high quality Eclipse.org: Challenges moving to a DVCS Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

No free lunch! … trust me, the only way to learn DVCS is to start using it... there is a learning curve, you need to rewire your brain! Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

EGit Demo Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

Introduction Hudson (Jenkins) and Mylyn Distributed Version Control (DVCS) Code Review with Git, Gerrit and Mylyn - What is Code Review? - Introduction to Gerrit - Mylyn Reviews Demo (Gerrit) Conclusion Q&A Agenda Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

What is Code Review? When one developer writes code, another developer is asked to review that code A careful line-by-line critique Happens in a non-threatening context Goal is cooperation, not fault-finding Often an integral part of coding process Debugging someone else's broken code – Involuntary code review: Not so good; emotions may flare [1] http://code.google.com/p/rietveld/downloads/detail?name=Mondrian2006.pdf Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

Code Review Benefits Four eyes catch more bugs § Catch bugs early to save hours of debugging Enforce coding standards § Keep overall readability & code quality high Mentoring of new developers § Learn from mistakes without breaking stuff Establish trust relationships § Prepare for more delegation Good alternative to pair programming § asynchronous and across locations [1] http://code.google.com/p/rietveld/downloads/detail?name=Mondrian2006.pdf Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

Gerrit Code Review Gerrit is a Code Review system based on JGit http://code.google.com/p/gerrit/ Also serves as a git server adding access control and workflow Used by • Android https://review.source.android.com/ • JGit, EGit http://egit.eclipse.org/r/ • Google, Red Hat, SAP, … Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

History: Google and code review tools Mondrian (Guido van Rossum) • based on Perforce, Google infrastructure • Google proprietary Rietvield (Guido van Rossum) • based on Subversion • Open Source hosted on GoogleApp Engine Gerrit (Shawn Pearce) • started as a fork of Rietvield • based on JGit and GWT • Open Source (Android) • Apache 2 license Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

One Branch One Feature Master branch contains only reviewed and approved changes • master moves from good to better state after each (approved) change Each feature branch is based on master branch • stable starting point A change can really be abandoned because • no other approved change can depend on a not yet approved change • Gerrit will automatically reject a successor change of an abandoned change Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

Gerrit – Lifecycle of a Change a master topic 1 • create local topic branch • commit change • push it for review • do review • automated verification Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

Gerrit – Lifecycle of a Change c b a 1 2 master topic 3 a master topic 1 • create local topic branch • commit change • push it for review • do review • automated verification • refine based on review • push new patchsets until review votes ok Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

Gerrit – Lifecycle of a Change c b a 1 2 master topic 3 a master topic 1 • create local topic branch • commit change • push it for review • do review • automated verification • refine based on review • push new patchsets until review votes ok c b a 1 2 master topic 3 d • Submit may lead to server-side merge • or merge / rebase before push Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

Gerrit Workflow Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

Gerrit http://egit.eclipse.org/r/ - change,825 Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

Gerrit and Mylyn Reviews Demo http://egit.eclipse.org/r/ - change,825 Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

History of Version Control (VCS) Hudson (Jenkins) and Mylyn Distributed Version Control (DVCS) Code Review with Git and Gerrit Conclusion Q&A Agenda Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

Conclusion The Mylyn project restructuring is a sign of maturity The future of version control is distributed! Mylyn Builds works great with Hudson (Jenkins) Gerrit enables a nice code review workflow Mylyn Reviews integrates with Gerrit Developing with Mylyn saves time! Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

Git Resources http://git-scm.com/documentation is your friend Watch Linus' talk at Google http://www.youtube.com/watch?v=4XpnKHJAok8 Read the Pro Git book - http://progit.org/book/ Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk

Q&A Evolution of Version Control in Open Source | © 2010 by Chris Aniszczyk Effective Development with Mylyn, Hudson, Git and Gerrit | © 2011 by Chris Aniszczyk