Welcome!

Linux Containers Authors: Liz McMillan, Yeshim Deniz, Elizabeth White, Derek Weeks, Patrick Hubbard

Related Topics: Linux Containers

Linux Containers: Article

Version Control with Subversion

A new source control system

Recently I had the opportunity to talk with the authors of Version Control with Subversion. In this interview, they discuss what Subversion is, migrating to Subversion, and, of course, music.

What is Subversion?
Subversion is an open source version control system. It was designed to be a compelling replacement for CVS - preserving the basic workflow and user experience of that system, but providing significant improvements over CVS's model (and its implementation).

Who hosts it and what license is it distributed under? Is the license OSI approved?
Subversion is hosted by CollabNet (www.collab.net), which also funds large parts of Subversion's development. The project calls Tigris.org - an online open source collaborative software development community - its home. Subversion is developed under CollabNet's license, which is a modified version of the Apache license (and fully compliant with the Debian Free Software Guidelines).

Are any large projects using Subversion now?
Absolutely. Subversion is currently being used by many large development teams, both open source and commercial. Some examples of large open source projects using Subversion include the folks at Samba, Zope, and Xiph. Notably, the Apache Software Foundation started using Subversion in early 2003, and started migrating projects to Subversion in earnest when Subversion reached 1.0 last February. Both Apache Geronimo and Apache SpamAssassin are using Subversion, and Apache HTTP Server is preparing to convert any day now.

What was wrong with CVS? Why was a new source control system needed?
CVS works just fine for file-based version control (as does RCS, the system atop which CVS is constructed). As it turns out, most projects typically involve more than one file, and that's when you start noticing creaks in the floors and cracks in the walls. CVS does not provide atomicity for changes across multiple files - does not, in fact, even have a notion of such a change "set." CVS does not do version changes to directory structure, such as file and subdirectory additions or removals, or items that are renamed. It's extremely inefficient in its handling of "binary" (nontextual) files. It was never designed with networks in mind; that support was entirely an afterthought.

Fixing these problems within the constraints of the basic CVS architecture was already a nonviable solution. But when you then examine the state of CVS's source code and lack of a modular, extensible design, you come away without a shadow of doubt - it was time to begin anew.

What are some of the cool new features of Subversion?
Besides fixing most of the major problems found in CVS, Subversion has additional perks. For example, the file and directories you keep under version control can have property lists - arbitrary name/value pairs - attached to them. Subversion itself uses these lists to track stuff like the MIME type, preferred line-ending style, keyword expansion setting, executability, etc. But users can set their own properties willy-nilly, and use them for whatever they would like. The properties themselves are versioned, too.

Another neat feature involves Subversion's network connectivity. Since one of the available server options is an Apache WebDAV module, you have at your fingers all the functionality and extensibility that Apache offers, plus a fair degree of WebDAV interoperability, all for free. This means you can refer directly to a Subversion repository URL when trying to get your grandmother to view the latest version of something you keep under version control, and Apache will just serve up that document like any other Web resource.

Readers should check out the Subversion Web site (http://subversion.tigris.org) for news about the latest and greatest coolness flowing from that community.

What steps should I take to migrate from CVS to Subversion?
Perhaps the biggest decision involved in a migration like this is what to do with all the versioned data you currently have stored in CVS repositories. For some folks, the answer is to just leave that data in CVS, take a "top-skim" of the latest versions of all the files in that repository, and import them into a new Subversion repository. But for those who desire a full migration of their CVS history, the cvs2svn tool (http://cvs2svn.tigris.org/) is the way to go.

Along the way you'll hit other decision-making points (a beautiful side effect of Subversion's modular design). For example, you'll have to choose between a pair of back-end storage mechanisms and decide which of a handful of network access routes you'd like to use with your repository.

Of course, you'll need a copy of Version Control with Subversion by your side! There is a section entitled "How to Read This Book" in the preface, which is perhaps the best launching point for the various audiences of the book, as well as a quick-start guide at the end of Chapter 1 aimed at helping folks get set up with enough of Subversion to start experimenting with it.

So you three helped write Subversion? Why did you get involved?
Ben: In 2000, I was still working as a Unix sysadmin, pining for a chance to code again. My buddy Karl Fogel and I had started writing some free software in our spare time, but then he got the call from CollabNet. Karl wasn't willing to move to San Francisco, so he got permission to pull together a Chicago-area team. Getting paid to write open source software (with your friends) is an almost unbelievable dream come true, so I jumped at the opportunity. Karl and I still joke that we originally thought it would take six months - not four years - to finish a 1.0 product!

Fitz: Back in 2000, Karl Fogel called me up to tell me that Brian Behlendorf had hired him at CollabNet to start work on the successor to CVS. I was very excited about the idea of Subversion (which was actually called "Inversion" back then) and started following Subversion's development and helped out here and there as time permitted. Eventually, I joined CollabNet full-time where I work with Karl, Mike, and Ben on Subversion and other various mind-control, um, I mean version-control related projects. I would like to state for the record that I do not and have never played the banjo.

Mike: Ben made me do it! Seriously, working on Subversion afforded me the opportunity to help design and implement a piece of software that promised to alleviate frustrations I was running into daily using CVS and Visual Source Safe. As my first foray into the open source culture, it gave me a chance to experience firsthand what all the buzz was about. When Ben and Karl called me up to say that they were now a year into their six-month project and needed a hand, I went to work for CollabNet.

In your office, musical instruments outnumber computers two-to-one. Are you really programmers?
No, we're musicians.

Although we're programmers by day, we've all got musical interests to some degree or other.

Fitz: Ben is an amazing musician who plays piano, guitar, and banjo, not to mention the fact that he's quite the barbershop singer too. When he's not programming, writing books, answering e-mail, or helping out Subversion users on IRC, Ben composes musicals and does sound design for theater with his collaborator, Andre Pluess. Quite frankly, I don't think he sleeps. Much to Ben's chagrin, floating around in my head are a handful of songs that he and Andre have written.

Ben: Mike is the "rocker" in our office. He's got a sweet PRS electric at home, but that doesn't prevent him from playing the same songs and progressive-rock licks on his acoustic guitar at the office. Mike plays in a very talented, very tight band called Autumn War. But he also writes and records a lot of his own thoughtful songs in his home studio. Call his cellphone sometime and listen to the outgoing message; it's hilarious. Though Mike's incessant desk drumming sometimes makes Fitz want to jump out the window.

Mike: Fitz grew up in the deep south. So while he claims the high tenor line during office barbershop quartet time (between morning snack and recess), his blues guitar licks are low-down, gritty goodness. In addition, he's the office DJ. He's got more muscle in his "iPod thumb" than the average hacker has on his whole body, and he has a truckload of diverse music to boot.

About Ben Collins-Sussman
Ben Collins-Sussman has been a sysadmin and programmer for 10 years, and is one of the original designers and authors of Subversion. He currently works for CollabNet as a Subversion developer and community leader. When away from his computer, he moonlights as a musical theater composer at theaters around the city of Chicago. He lives with his lovely wife, three cats, and a house full of computer and music gizmos.

About Brian W. Fitzpatrick
Brian W. Fitzpatrick is a member of the Apache Software Foundation and currently works for CollabNet. He has been involved with Subversion in one way or another since its inception in early 2000. Originally from New Orleans, Brian moved to Chicago to attend Loyola University where he received a degree in Latin and Greek.

About C. Michael Pilato
C. Michael Pilato (Mike) is a core Subversion developer, and a leader in the Subversion community. He is currently employed by CollabNet, where he spends his days (and many nights) improving Subversion and other tools with which it integrates. A husband and father, this North Carolina native also enjoys composing and performing music, freelance graphic design work, hiking, and spending quality time with his family. Mike has a degree in computer science and mathematics from the University of North Carolina at Charlotte.

More Stories By Kevin Bedell

Kevin Bedell, one of the founding editors of Linux.SYS-CON.com, writes and speaks frequently on Linux and open source. He is the director of consulting and training for Black Duck Software.

Comments (0)

Share your thoughts on this story.

Add your comment
You must be signed in to add a comment. Sign-in | Register

In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.


@ThingsExpo Stories
DX World EXPO, LLC., a Lighthouse Point, Florida-based startup trade show producer and the creator of "DXWorldEXPO® - Digital Transformation Conference & Expo" has announced its executive management team. The team is headed by Levent Selamoglu, who has been named CEO. "Now is the time for a truly global DX event, to bring together the leading minds from the technology world in a conversation about Digital Transformation," he said in making the announcement.
SYS-CON Events announced today that DXWorldExpo has been named “Global Sponsor” of SYS-CON's 21st International Cloud Expo, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Digital Transformation is the key issue driving the global enterprise IT business. Digital Transformation is most prominent among Global 2000 enterprises and government institutions.
SYS-CON Events announced today that Datera, that offers a radically new data management architecture, has been named "Exhibitor" of SYS-CON's 21st International Cloud Expo ®, which will take place on Oct 31 - Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Datera is transforming the traditional datacenter model through modern cloud simplicity. The technology industry is at another major inflection point. The rise of mobile, the Internet of Things, data storage and Big...
While the focus and objectives of IoT initiatives are many and diverse, they all share a few common attributes, and one of those is the network. Commonly, that network includes the Internet, over which there isn't any real control for performance and availability. Or is there? The current state of the art for Big Data analytics, as applied to network telemetry, offers new opportunities for improving and assuring operational integrity. In his session at @ThingsExpo, Jim Frey, Vice President of S...
"We provide IoT solutions. We provide the most compatible solutions for many applications. Our solutions are industry agnostic and also protocol agnostic," explained Richard Han, Head of Sales and Marketing and Engineering at Systena America, in this SYS-CON.tv interview at @ThingsExpo, held June 6-8, 2017, at the Javits Center in New York City, NY.
"We've been engaging with a lot of customers including Panasonic, we've been involved with Cisco and now we're working with the U.S. government - the Department of Homeland Security," explained Peter Jung, Chief Product Officer at Pulzze Systems, in this SYS-CON.tv interview at @ThingsExpo, held June 6-8, 2017, at the Javits Center in New York City, NY.
"We are focused on SAP running in the clouds, to make this super easy because we believe in the tremendous value of those powerful worlds - SAP and the cloud," explained Frank Stienhans, CTO of Ocean9, Inc., in this SYS-CON.tv interview at 20th Cloud Expo, held June 6-8, 2017, at the Javits Center in New York City, NY.
The financial services market is one of the most data-driven industries in the world, yet it’s bogged down by legacy CPU technologies that simply can’t keep up with the task of querying and visualizing billions of records. In his session at 20th Cloud Expo, Karthik Lalithraj, a Principal Solutions Architect at Kinetica, discussed how the advent of advanced in-database analytics on the GPU makes it possible to run sophisticated data science workloads on the same database that is housing the rich...
Internet of @ThingsExpo, taking place October 31 - November 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with 21st Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world. The Internet of Things (IoT) is the most profound change in personal and enterprise IT since the creation of the Worldwide Web more than 20 years ago. All major researchers estimate there will be tens of billions devic...
"The Striim platform is a full end-to-end streaming integration and analytics platform that is middleware that covers a lot of different use cases," explained Steve Wilkes, Founder and CTO at Striim, in this SYS-CON.tv interview at 20th Cloud Expo, held June 6-8, 2017, at the Javits Center in New York City, NY.
SYS-CON Events announced today that Calligo, an innovative cloud service provider offering mid-sized companies the highest levels of data privacy and security, has been named "Bronze Sponsor" of SYS-CON's 21st International Cloud Expo ®, which will take place on Oct 31 - Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Calligo offers unparalleled application performance guarantees, commercial flexibility and a personalised support service from its globally located cloud plat...
"MobiDev is a Ukraine-based software development company. We do mobile development, and we're specialists in that. But we do full stack software development for entrepreneurs, for emerging companies, and for enterprise ventures," explained Alan Winters, U.S. Head of Business Development at MobiDev, in this SYS-CON.tv interview at 20th Cloud Expo, held June 6-8, 2017, at the Javits Center in New York City, NY.
SYS-CON Events announced today that DXWorldExpo has been named “Global Sponsor” of SYS-CON's 21st International Cloud Expo, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Digital Transformation is the key issue driving the global enterprise IT business. Digital Transformation is most prominent among Global 2000 enterprises and government institutions.
In his opening keynote at 20th Cloud Expo, Michael Maximilien, Research Scientist, Architect, and Engineer at IBM, discussed the full potential of the cloud and social data requires artificial intelligence. By mixing Cloud Foundry and the rich set of Watson services, IBM's Bluemix is the best cloud operating system for enterprises today, providing rapid development and deployment of applications that can take advantage of the rich catalog of Watson services to help drive insights from the vast t...
SYS-CON Events announced today that EnterpriseTech has been named “Media Sponsor” of SYS-CON's 21st International Cloud Expo, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. EnterpriseTech is a professional resource for news and intelligence covering the migration of high-end technologies into the enterprise and business-IT industry, with a special focus on high-tech solutions in new product development, workload management, increased effic...
SYS-CON Events announced today that Massive Networks, that helps your business operate seamlessly with fast, reliable, and secure internet and network solutions, has been named "Exhibitor" of SYS-CON's 21st International Cloud Expo ®, which will take place on Oct 31 - Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. As a premier telecommunications provider, Massive Networks is headquartered out of Louisville, Colorado. With years of experience under their belt, their team of...
SYS-CON Events announced today that Cloud Academy named "Bronze Sponsor" of 21st International Cloud Expo which will take place October 31 - November 2, 2017 at the Santa Clara Convention Center in Santa Clara, CA. Cloud Academy is the industry’s most innovative, vendor-neutral cloud technology training platform. Cloud Academy provides continuous learning solutions for individuals and enterprise teams for Amazon Web Services, Microsoft Azure, Google Cloud Platform, and the most popular cloud com...
SYS-CON Events announced today that Cloudistics, an on-premises cloud computing company, has been named “Bronze Sponsor” of SYS-CON's 21st International Cloud Expo, which will take place on Oct 31 - Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Cloudistics delivers a complete public cloud experience with composable on-premises infrastructures to medium and large enterprises. Its software-defined technology natively converges network, storage, compute, virtualization, and ...
SYS-CON Events announced today that CHEETAH Training & Innovation will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct. 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. CHEETAH Training & Innovation is a cloud consulting and IT training firm specializing in improving clients cloud strategies and infrastructures for medium to large companies.
SYS-CON Events announced today that Datanami has been named “Media Sponsor” of SYS-CON's 21st International Cloud Expo, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Datanami is a communication channel dedicated to providing insight, analysis and up-to-the-minute information about emerging trends and solutions in Big Data. The publication sheds light on all cutting-edge technologies including networking, storage and applications, and thei...