Agile Software Development

SOA & WOA Magazine on Ulitzer

WANdisco announced that an increasing number of its customers are implementing Subversion MultiSite and Subversion Clustering to support agile practices across their large distributed development organizations. At the core of agile software development is constant collaboration between developers and continuous build integration. These customers found that a centralized server or even a proxy-server architecture was unable to effectively support agile software development with Subversion.

Agile development’s primary objective is the frequent delivery of working code. In practice this imposes two key requirements on a development organization: (1) there must be constant collaboration between developers and; (2) continuous build integration that is fast, automated and reliable must be in place. Central server or master–slave solutions such as svnsync can’t address these requirements in a large distributed development organization for the following reasons:

• Continuous build integration becomes impractical, because the latest changes are not available from remote sites. This makes it impossible to implement continuous build integration and fully automate the build process.
• Master-slave solutions don’t support parallel build processes at each site if build scripts include write steps. Commits and all other write operations can only be done against a master, resulting in the same limitations imposed by a central server implementation.
• Effective collaboration requires that developers have continual access to each other’s latest changes. Poor and unreliable network performance often leads developers at remote sites into a pattern of holding back their changes as long as possible, often until the end of each work week. Once the build process begins the following week, merge conflicts and other issues are uncovered that result in broken builds.

With Subversion MultiSite each site can perform builds and test locally with the latest code. The delays caused by broken builds and scheduling issues with a centralized build team go away. Merge conflicts and other problems are caught and fixed when they occur. The latest changes are always available everywhere and everything happens at local area network speed. WANdisco’s customers such as SSP have reported significant reduction in their build, test and deploy cycles.

“Subversion MultiSite has transformed our software development process,” said David Stokes, IT Manager, SSP. “We can now run builds at every site immediately which means that nobody is waiting for a build to happen in a different time zone. The bottom line is that we improved build times by over 500% and reduced our development cycles by 40%. We looked at using svnsync, but we found that it wasn’t as stable as it needed to be and wasn’t a fit for what we were trying to accomplish with our build process.”

A recent Forrester Research Total Economic Impact study of Subversion MultiSite found that the ability to access the latest changes and perform builds in parallel at each location eliminated two man-days of developer idle time each day. The number of builds completed on a daily basis also increased by 100%. Forrester found this to be a significant factor contributing to the 167% return on investment and 9 month payback period cited in the study. As a development manager quoted by Forrester said, “…builds were much more real time and people were able to more agilely track what changes are happening in the Subversion source tree, and it made the groups that were distant actually work better together when they didn’t have to wait for things to happen…”

A number of enterprises are also turning to Subversion Clustering to support agile development. Subversion Clustering leverages the same replication technology used by Subversion MultiSite. Build processes can be offloaded from the Subversion server used by the development team, so that their productivity is enhanced. At the same time, the latest changes from the development team are available on the servers where continuous build processes are running. In many cases WANdisco’s customers are implementing Subversion Clustering in combination with Subversion MultiSite. This combined approach allows WAN latency to be eliminated along with the performance bottleneck of a single Subversion server at the largest development sites.

“We are extremely pleased that so many large distributed enterprises are realizing the savings in time and cost that our unique technology brings to the application development lifecycle,” said David Richards, President and CEO of WANdisco. “Successful implementation of agile development practices is a key component of achieving these cost-savings and productivity improvements and our customers tell us that they couldn’t do this without WANdisco products.”