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Re: Subversion Vision and Roadmap Proposal

From: Hyrum K. Wright <hyrum_wright_at_mail.utexas.edu>
Date: Sat, 10 Apr 2010 23:27:16 +0100

While there has been lots of discussion about aspects of the following,
there really hasn't been any dissent about the core vision and other ideas
presented below. Given that, I propose that we massage this into a public,
web-facing statement, and put it on the website somewhere. I can start
working on that next week, if nobody beats me to it.


On Fri, Apr 2, 2010 at 4:28 PM, C. Michael Pilato <cmpilato_at_collab.net>wrote:

> Last week, five of Subversion's developers -- myself, Hyrum Wright (who
> helped me author this lengthy mail), Greg Stein, Stefan Sperling, and Karl
> Fogel ("we", henceforth) -- met in New York City to evaluate Subversion's
> current trajectory as a project and to jointly develop suggestions for any
> course correction deemed necessary. The unfortunate impetus for the
> meeting
> was feedback from representatives of some very large installations of
> Subversion that, from where they sat, the Subversion project was
> stagnating.
> This is a somewhat fair assertion. It's not that the community is or has
> ever been in danger of doing nothing. But even when we march in step
> towards a goal, we don't do a good job of communicating outwardly about
> that
> fact, leading to the appearance of inactivity. And lately, our ongoing
> efforts have been less like a team of folks working in concert towards a
> common vision, and more like the individual piddlings common to mature open
> source software.
> Make no mistake: Subversion is mature open source software. It works well
> for open source projects and -- in one of the biggest software coups of the
> last decade -- we've found that it's also good enough to supplant other
> well-established version control systems, open-source or otherwise, inside
> the highly structured walls of the enterprise. Unfortunately, "good
> enough"
> still leaves the enterprise user base frustrated at the most inopportune
> times (like, say, when managing branches near releases). And if you judge
> success by mindshare, it's now clear the DVCS tools have rendered our "good
> enough" somewhat obsolete when it comes to serving many open source
> projects, even.
> Subversion has no future as a DVCS tool. Let's just get that out there.
> At
> least two very successful such tools exist already, and to squeeze another
> horse into that race would be a poor investment of energy and talent.
> What's more, huge classes of users remain categorically opposed to the very
> tenets on which the DVCS systems are based. They need centralization.
> They
> need control. They need meaningful path-based authorization. They need
> simplicity. In short, they desperately need Subversion. It's this class
> of
> user -- the corporate developer -- that stands to benefit hugely from what
> Subversion brings to the party. And it's that class of user which we
> believe Subversion should cater to, ideally without ostracizing the open
> source volunteers who remain our largest source of development investment.
> Corporate developers come in all shapes and sizes, from self-administering
> 10-person teams to geographically-distributed organizations of thousands of
> developers on hundreds of teams serviced by dedicated IT departments.
> Subversion can't be all things to all people, but it can be a well-defined
> subset of things to most people. It shouldn't sacrifice its trademark
> simplicity when growing the features most likely to be used in large-scale
> deployments; it shouldn't optimize for the large enterprise in a way that
> will alienate the long tail composed of much smaller deployments. By
> defining the subset of things Subversion is and those it is not, we
> recognize our own boundaries and prevent years of wandering through the
> proverbial wilderness of feature creep.
> Someone wiser than I once said, "Where there is no vision, the people
> perish." So recognizing the benefits that Subversion already offers, and
> projecting a bit into the future what we'd like to see Subversion become,
> we
> offer the following vision statement for your review:
> Subversion exists to be universally recognized and adopted as an
> open-source, centralized version control system characterized by its
> reliability as a safe haven for valuable data; the simplicity of its
> model and usage; and its ability to support the needs of a wide variety
> of users and projects, from individuals to large-scale enterprise
> operations.
> A shorter, business-card-sized motto (offered as a replacement to the
> obsolete "A compelling replacement for CVS") might be: "Enterprise-class
> centralized version control for the masses".
> With that vision in mind, we identified a number of high-value improvements
> which Subversion should gain in coming releases. Then we took a casual
> pass
> at assigning some technical "plumbing" dependencies for each of these.
> Here's what we came up with, in the form "FEATURE: [DEPENDENCY ...]", where
> "FS-NG" = major FS backend overhaul, "WC-NG" = WC-NG, and "Ev2" =
> svn_editor_t:
> * Obliterate: FS-NG
> * Shelve/Checkpoint: WC-NG
> * Repository-dictated Configuration: WC-NG (?)
> * Rename Tracking: WC-NG, Ev2, FS-NG (?)
> * Improved Merging: WC-NG
> * Improved Tree Conflict Handling: WC-NG, Ev2, Rename Tracking
> * Enterprise Authentication Mechanisms:
> * Forward History Searching: FS-NG (?)
> * Log Message Templates: Repository-dictated Configuration
> By examining this dependency chain, factoring in the development momentum
> which will exist around WC-NG, and admitting that some of the major
> plumbing
> overhauls not currently underway may prove to be just as costly as the
> work (if not more so), we believe that the following feature roadmap is one
> which will serve Subversion users well:
> 1.7: WC-NG; HTTPv2; 'svn patch'; typical slew of various bug fixes
> 1.8: repository-dictated configuration; tree conflicts improvements;
> WC-NG-enabled stuff (rename tracking, compressed pristines,
> shelving/checkpointing, ...)
> 1.9: Editor v2 (for server->client rename handling improvements)
> [...]
> 2.0: FS-NG (ideally a parallelized task), with some (to-be-identified)
> FS-NG enabled features.
> That last item is likely to be contentious, so it bears explaining. We
> believe that our current two filesystem offerings are stifling innovation.
> On the one hand we have the BDB backend which is a breeze to develop for
> but
> is only occasional used; on the other is the far-more-popular FSFS backend
> whose fundamental principles so constrain the system as to destroy much
> hope
> of serious design overhaul; and in the middle lies the feature parity
> requirement we've been living under thus far which binds Subversion to the
> union of the two backends' weaknesses. We confidently assert that to break
> system-wide compatibility with a so-called 2.0 release will be Subversion's
> great overall detriment, both from the perspective of efficient use of
> development energy and in user adoption. So we propose that an
> as-yet-fictional Subversion 2.0 be allowed to break compatibility with the
> 1.x line only in ways which can be mitigated using the RA layer as a
> compatibility shim. Additionally, we believe that merely releasing a 2.0
> with a new FS backend but without new user-visible features enabled by that
> overhaul will be ill-received.
> We also discussed matters of communication and community. Subversion has
> historically had a very tight-knit community of developers, and we've
> provided a resource for communicating with users through the various
> mailing
> lists. With the increase in corporate involvement, and the changing roles
> (and employers!) of committers, the Subversion ecosystem can at times seems
> a bit fractured. To an enterprise manager responsible for thousands of
> users, and millions of dollars of investment, and billions of bytes of
> data,
> this fracturing appears as a liability when considering an investment in
> Subversion. Most corporations understand the open source nature of
> Subversion's development method (indeed, this very thing has driven
> Subversion adoption), but they still want a unified face when it comes to
> communication, planning, and project feedback.
> One proposed solution is a Subversion "planet", to be hosted at a
> re-purposed subversion.org. The planet would aggregate feeds from
> individual contributors, as well as the various corporate entities
> interested in Subversion development. While various commercial interests
> (CollabNet, WANdisco, elego, etc.) may compete in some areas, they are all
> committed to improving Subversion as a whole. Enterprise users need to see
> this unity across Subversion's corporate sponsors, and a communication
> stream which interleaves these corporate voices works toward that end.
> Whatever the solution, we need a defined plan which we then communicate to
> the end users and customers who are deploying Subversion installations.
> But communication alone isn't enough. We need to find ways to grow our
> developer community itself. Attendance at the recent Subversion
> Corporation
> Annual Members Meeting was low (by design and recommendation, of course),
> but a startling realization was made there. When the agenda item for
> voting
> new full committers into membership was on the table, there were no
> candidates. Think about that: no new full committers for Subversion in
> the
> past year. This is a bad thing. We need to find a way to embrace and
> empower would-be Subversion contributors. Telling them to troll through
> the
> issue tracker looking for bite-sized issues is not the way to do that -- it
> communicates "we can't be bothered to mentor you". When somebody wants to
> start making contributions, our community must recognize the value of that
> contributor and mentor him or her toward full committership, for the good
> of
> that contributor and of the community. Further, our public roadmap needs
> to
> highlight the items that we really wish we could be working on but lack the
> manpower to handle. This would provide those looking for ways to
> accelerate
> Subversion's roadmap with some cues for doing that in harmony with the Big
> Picture.
> I've covered a lot of ground here, but decisions in this community have
> always been and will be made on this mailing list, and they deserve to be
> made with as much information as possible. You now know where a small
> contingent of developers stand on these issues. I'd like to publicize on
> our project website a *community-endorsed* vision and roadmap ASAP, and
> then
> get to the business of moving Subversion forward along those lines.
> So what say you?
> -- C-Mike, for the NYC conference attendees
> --
> C. Michael Pilato <cmpilato_at_collab.net>
> CollabNet <> www.collab.net <> Distributed Development On Demand
Received on 2010-04-11 00:27:42 CEST

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