WANdisco Blog

On Achieving Consensus

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“Our life is what our thoughts make it.” M. Aurelius, 121 AD – 180 AD

Since WANdisco is a distributed computing company, you might be thinking this will be another article on the subtleties of obtaining consensus between multiple processors using the Paxos algorithm.

Almost, except without the computers.

Recently we had a kickoff summit for a new product. The core team met here in San Ramon, gathered from Belfast, Sheffield and Massachusetts.  We all have significantly different backgrounds, live in four different places, and came together for a few days to try to sort out a beefy list of major questions about integration points, requirements and architecture for the new product.

The technical chops of the group were without question, the motivation high, and the time short. It seemed clear that this was a challenge primarily of consensus.  We had to resolve our list of open questions efficiently and decisively.

And despite coming into the meeting with many questions still unresolved after long email exchanges, we did! The process was the quickest and most effective I’ve experienced in 25 years building enterprise software, and I started to wonder if WANdisco’s core technology of achieving consensus between computers was bleeding over and helping humans reach consensus as well.

It occurred to me that maybe it has something to do with the language that I overhear from the development teams. They speak constantly of “proposals”, “agreements”, “consensus”.  In my programming days, I recall using words like “cast”, “derive”, “protected”. Could the simple use of highly cooperative language have a beneficial side effect on group decision making?

Absolutely, and it’s variously described as Linguistic Relativity, Sapir–Whorf hypothesis, or Whorfianism.  In short, it’s the theory that the language we employ affects our thoughts and subsequent actions.

Looks like we caught an example of this in action. How might the language you use in your software development process affect your ability to reach consensus on big decisions?

 

 

 

 

 

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About James Creasy

James Creasy is Senior Director Product Management, setting strategic direction and overseeing development for WANdisco's ALM products. As in his previous role as Director of Product Technology at Perforce Software, James explores emerging technologies to identify new approaches to product offerings, competitive positioning, and business architectures.

WANdisco CEO, David Richards, presents at Tech London Advocates Launch as Founding Member

Last week saw the launch of Tech London Advocates, a new advocacy group launched by angel and venture investor Russ Shaw to support London’s technology start-ups into high growth.

 

With a founding membership of 150 comprising international CEOs, CTOs, fund managers and private investors, Tech London Advocates launched with an event featuring presentations by high profile executives, including our own founder and CEO, David Richards.

 

High profile supporters of Tech London Advocates include Saul Klein, partner at Index Ventures; David Richards, founder and CEO of WANdisco; Julie Meyer, founder of Ariadne Capital; Sherry Coutu, co-chair of Silicon Valley comes to the UK; Simon Devonshire, director at Wayra Europe, Dan Crow, CTO of Songkick and Rajeeb Dey, CEO and founder of Enternships.

 

Tech London Advocates will work in partnership with existing groups and initiatives to support ongoing efforts to establish London as a world-class hub for digital and technology businesses. WANdisco is honored to be part of the advocacy group.

 

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About Mand

I look after the WANdisco Community, on svnforum.org, Twitter, Facebook, Linkedin and all the usual places people hang out on the web. I'm also involved with support, documentation, and internal processes.

Understanding SmartSVN’s Revision Graph

SmartSVN, the popular cross-platform client for Apache Subversion, provides all the tools you need to manage your SVN projects out of the box, including a comprehensive Revision Graph.

SmartSVN’s Revision Graph offers an insight into the hierarchical history of your files and directories, by displaying information on:

  • Merged revisions

  • Revisions yet to be merged

  • Whether a merge occurred in a specific revision

  • Which changes happened in which branch

  • When a file was moved, renamed or copied, along with its history

The Revision Graph is useful in several tasks, including identifying changes made in each revision before rolling back to a previous revision, and gathering more information on the state of a project before a merge.

Accessing the Revision Graph

To access the Revision Graph, open the ‘Query’ menu and select ‘Revision Graph.’

revision graph

Understanding the Revision Graph

In the Revision Graph, projects are mainly represented by:

node Nodes – represent a specific entry (file/directory) at a specific revision.

branch 

    Branches – a collection of linked nodes at the same URL.

 

 

The main section of the Revision Graph is the ‘Revisions’ pane, which displays the parent-child relationships between revisions. Revisions are arranged by date, with the newest at the top. In addition to the main ‘Revisions’ pane, the SmartSVN Revision Graph includes several additional views:

  • Revision Info – displays information on the selected revision (such as revision number, date, author who created the revision etc.)

revision info

  • Directories and files – displays modified files in the selected revision. This is useful for pinpointing the revision at what point a particular file changed or disappeared from the project.

From this screen, you can access several additional options:

  • Export – export the Revision Graph as an HTML file by selecting ‘Export as HTML…’ from the ‘Graph’ menu. This file can then be easily shared with other team members.

  • Merge Arrows – select the ‘Show Merge Arrows’ option from the ‘Query’ menu to view the merge arrows. These point from the merge source to the merge target revisions. If the merge source is a range of revisions, the corresponding revisions will be surrounded by a bracket. This allows you to get an overview of merges that have occurred within your project, at a glance.

  • Merge Sources – select the ‘Show Merge Sources’ option from the ‘Query’ menu to see which revisions have been merged into the currently selected target revision.

  • Merge Targets – select ‘Show Merge Targets’ from the ‘Query’ menu to see the revisions where the currently selected target revisions have been merged.

  • Search – if you’re looking for a particular revision, you can save time by using ‘Edit’ and ‘Search.’ Enter the ‘Search For’ term and specify a ‘Search In’ location.

  • Branch Filter – clicking the ‘Branch Filter’ option in the ‘View’ menu allows you to filter the display for certain branches. This is particularly useful if you’re examining a large project consisting of many different branches.

WANdisco Announces SVN MultiSite Plus

We are proud to announce SVN MultiSite Plus, the newest product in our enterprise Subversion product line. WANdisco completely re-architected SVN MultiSite and the result is SVN MultiSite Plus, a replication software solution delivering dramatically improved performance, flexibility and scalability for large, global organizations.

SVN MultiSite Plus enables non-stop performance, scalability and backup, alongside 24/7 availability for globally distributed Apache Subversion deployments. This new product takes full advantage of recent enhancements to our patented active-active replication technology to improve flexibility, scalability, performance and ultimately developer and administrator productivity.

“SVN MultiSite has been improving performance and productivity for global enterprises since 2006 and SVN MultiSite Plus builds on those features for even greater benefits,” said David Richards, WANdisco CEO. “We’re committed to providing organizations with the most robust and flexible solutions possible and we’re confident SVN MultiSite Plus will meet and exceed the requirements of the largest globally distributed software development organizations.”

To find out more, visit our SVN MultiSite Plus product page, download the datasheet, or see how it compares to SVN MultiSite. You can try SVN MultiSite Plus firsthand by signing up for a free trial, or attend the free, online SVN MultiSite Plus demo we’ll be holding on May 1st. This webinar will demonstrate how SVN MultiSite Plus:

  • Eliminates up to 90% of communication overhead at each location

  • Eliminates downtime completely by providing administrators with the ability to add/remove servers on-the-fly

  • Delivers additional savings over SVN MultiSite through tools consolidation and greater deployment flexibility

  • Provides increased efficiency and flexibility with selective repository replication

  • And more.

This webinar is free but register now to secure a spot.

Subversion Tip of the Week

An Apache Subversion working copy can be created quite simply by running the ‘svn checkout’ command. However, sometimes you’ll want to have more control over the contents of your working copy; for example, when you’re working on a large project and only need to checkout a single directory.

In this post, we share two ways to get greater control over your checkout commands.

1. Checkout a particular revision

By default, Subversion performs a checkout of the HEAD revision, but in some instances you may wish to checkout a previous revision, for example when you’re recovering a file or directory that has been deleted in the HEAD revision.

To specify a revision other than HEAD, add the -r switch when performing your checkout:

svn checkout (URL) -r(revision number) (Location)

In this example, we are performing a checkout of the project as it existed at revision 10.

customizing working copy

2. Performing Shallow Checkouts

A standard Subversion checkout copies the entire directory, including every folder and file. This can be too time-consuming if you’re working on a large project, or too complicated if your project contains many different branches, tags and directories. If you don’t require a copy of your entire project, a ‘shallow checkout’ restricts the depth of the checkout by preventing Subversion from descending recursively through the repository.

To perform a shallow checkout, run the ‘svn checkout’ command with one of the following switches:

  • –depth immediates: checkout the target and any of its immediate file or children. This is useful if you don’t require any of the children’s contents.

  • –depth files: checkout the target and any of its immediate file children.

  • –depth empty: checkout the target only, without any of the files or children. This is useful when you’re working with a large project, but only require the contents of a single directory.

In this example we are performing a shallow checkout on a ‘bug fix branch’ located within the branches folder, and specifying that only the immediate file children should be included (–depth files):

customizing working copy 2

Looking for a cross-platform Subversion client? Get a free trial of SmartSVN Professional at www.smartsvn.com/download

WANdisco Releases New Version of Hadoop Distro

We’re proud to announce the release of WANdisco Distro (WDD) version 3.1.1.

WDD is a fully tested, production-ready version of Apache Hadoop 2 that’s free to download. WDD version 3.1.1 includes an enhanced, more intuitive user interface that simplifies Hadoop cluster deployment. WDD 3.1.1 supports SUSE Linux Enterprise Server 11 (Service Pack 2), in addition to RedHat and CentOS.

“The number of Hadoop deployments is growing quickly and the Big Data market is moving fast,” said Naji Almahmoud, senior director of global business development, SUSE, a WANdisco Non-Stop Alliance partner. “For decades, SUSE has delivered reliable Linux solutions that have been helping global organizations meet performance and scalability requirements. We’re pleased to work closely with WANdisco to support our mutual customers and bring Hadoop to the enterprise.”

All WDD components are tested and certified using the Apache BigTop framework, and we’ve worked closely with both the open source community and leading big data vendors to ensure seamless interoperability across the Hadoop ecosystem.

“The integration of Hadoop into the mainstream enterprise environment is increasing, and continual communication with our customers confirms their requirements – ease of deployment and management as well as support for market leading operating systems,” said David Richards, CEO of WANdisco. “With this release, we’re delivering on those requirements with a thoroughly tested and certified release of WDD.”

WDD 3.1.1 can be downloaded for free now. WANdisco also offers Professional Support for Apache Hadoop.

Apache Subversion Team Releases 1.7.9 and 1.6.21

The Apache Subversion team has announced two new releases: Subversion 1.7.9 and 1.6.21.

Subversion 1.7.9 improves the error messages for svn:date and svn:author props, and it improves the logic in mod_dav_svn’s implementation of lock, as well as a list of other features and fixes:

  • Doxygen docs now ignore prefixes when producing the index

  • Javahl status api now respects the ignoreExternals boolean

  • Executing unnecessary code in log with limit is avoided

  • A fix for a memory leak in `svn log` over svn://

  • An incorrect authz failure when using neon http library has been fixed

  • A fix for an assertion when rep-cache is inaccessible

More information on Apache Subversion 1.7.9 can be found in the Changes file.

Meanwhile, Subversion 1.6.21 improves memory usage when committing properties in mod_dav_svn, and also improves logic in mod_dav_svn’s implementation of lock, alongside bug fixes including:

  • A fix for a post-revprop-change error that could cancel commits

  • A fix for a compatibility issue with g++ 4.7

More information on Apache Subversion 1.6.21 can be found in the Changes file.

Both versions can be downloaded free via the WANdisco website.

Free Webinar: Enterprise-Enabling Hadoop for the Data Center

We’re pleased to announce that WANdisco will be co-hosting a free Apache Hadoop webinar with Tony Baer, Ovum’s lead Big Data analyst. Ovum is an independent analyst and consultancy firm specializing in the IT and telecommunications industries.

This webinar, ‘Big Data – Enterprise-Enabling Hadoop for the Data Center’, will cover the key issues of availability, performance and scalability and how Apache Hadoop is evolving to meet these requirements.

“This webinar will discuss the importance of availability, performance and scalability,” said Ovum’s Tony Baer. “Ovum believes that for Hadoop to become successfully adopted in the enterprise, that it must become a first class citizen with IT and the data center. Availability, performance and scalability are key issues, and also where there is significant innovation occurring. We’ll discuss how the Hadoop platform is evolving to meet these requirements.”

Topics include:

  • How Hadoop is becoming a first class, enterprise-hardened technology for the data center
  • Hadoop components and the role of reliability and performance in those components

  • Disaster recovery challenges faced by globally distributed organizations and how replication technology is crucial to business continuity

  • The importance of seamless Hadoop migration from the public cloud to private clouds, especially for organizations that require secure 24/7 access with real-time performance

Big Data – Enterprise-Enabling Hadoop for the Data Center’ will be held on Tuesday, April 30th at 10:00 am Pacific / 1:00 pm Eastern. Register for this free webinar here.

Introduction to SmartSVN

SmartSVN is a powerful and easy-to-use graphical client for Apache Subversion. There are several clients for Subversion, but here are just a few reasons you should try SmartSVN:

  • It’s cross-platform – SmartSVN runs on Windows, Linux and Mac OS X, so you can continue using the operating system (OS) that works the best for you. It can also be integrated into your OS, via Mac’s Finder Integration or Windows Shell.

  • Everything you need, out of the box – SmartSVN comes complete with all the tools you need to manage your Subversion projects:

  1. Conflict solver – this feature combines the freedom of a general, three-way-merge with the ability to detect and resolve any conflicts that occur during the development lifecycle.

  2. File compare – this allows you to make inner-line comparisons and directly edit the compared files.

  3. Built-in SSH client – allows users to access servers using the SSH protocol. This security-conscious protocol encrypts every piece of communication between the client and the server, for additional protection.

  • A complete view of your project at a glance – the most important files (such as conflicted, modified or missing files) are placed at the top of the file list. SmartSVN also highlights which directories contain local modifications, which directories have been changed in the repository, and whether individual files have been modified locally or in the central repo. This makes it easy to get a quick overview of the state of your project.

  • Fully customizable – maximize productivity by fine-tuning your SmartSVN installation to suit your particular needs: Change keyboard shortcuts, write your own plugin with the SmartSVN API, group revisions to personalize your display, create Change Sets, and alter the context menus and toolbars to suit you. You can learn more about customizing SmartSVN at our ‘5 Ways to Customize SmartSVN’ blog post.

  • Comprehensive bug tracker support – Trac and JIRA are both fully supported.

Multitude of support options – SmartSVN users have access to a range of free support, from refcards to blogs and documentation, the SmartSVN forum and a Twitter account maintained by our open source experts. If you need extra support with your SmartSVN installation, expert email support is included with SmartSVN Professional licenses.

Want to learn more about SmartSVN? On April 18th, WANdisco will be be holding a free ‘Introduction to SmartSVN’ webinar covering everything you need to get off to a great start with this popular client:

  • Repository basics

  • Checkouts, working folders, editing files and commits

  • Reporting on changes

  • Simple branching

  • Simple merging

This webinar is free so register now.

Subversion Tip of the Week

Tagging and Branching with SmartSVN’s ‘Copy Within Repository’

SmartSVN’s ‘Copy Within Repository’ command allows users to perform pure repository copies, which is particularly useful for quickly creating tags and branches.

To create a repository copy within SmartSVN:

1) Open the ‘Modify’ menu and select ‘Copy within Repository’.

2) From the ‘Copy From’ dropdown menu, select the repository where the source resides.

3) In the ‘Copy From’ textbox, specify the directory being copied. In ‘Source Revision,’ tell SmartSVN whether it should copy the HEAD revision (this is selected by default) or a different revision. Use the ‘Browse’ button if you need more information about the contents of the different directories and/or revisions that make up your project.

copy within repo

4) Select either:

  • Copy To – source is copied into the ‘Directory’ under the filename specified by ‘With Name’

  • Copy Contents Into – the contents of the source are copied directly into the ‘Directory’ under ‘With Name.’

5) Enter the copy’s destination in the ‘Directory’ textbox. You can view the available options by clicking the ‘Browse’ button.

6) Give your copy a name in the ‘With Name’ textbox.

7) The copy is performed directly in the repository, so you’ll need to enter an appropriate commit message.

8) Once you’re happy with the information you’ve entered, hit ‘Copy’ to create your new branch/tag.

Try SmartSVN Professional free today! Get a free trial at http://www.smartsvn.com/download.