Nexus is a framework for developing and sustaining large software development projects. The Nexus Guide can be used next to the Scrum Guide to scale Scrum and support the integrated effort of multiple software development teams.
Earlier this year InfoQ published a Q&A with Gunther Verheyen on Scaled Professional Scrum and the Nexus Framework. Gunther Verheyen will talk about Scaled Professional Scrum at the Agile Greece Summit 2015; InfoQ will cover this conference.
InfoQ interviewed Ken Schwaber, author of the Nexus Guide and one of the original authors and signatories of the Agile Manifesto, about the Nexus framework and guide, how Nexus adds on to Scrum, the Nexus integration team, scrum of scrums and the Nexus daily scrum, aligning retrospectives and improvement actions over teams, and how Nexus relates to other scaling approaches.
InfoQ: Can you briefly describe the Nexus guide? What made you decide to publish it?
Schwaber: The Nexus guide is the companion, in all respects, to the Scrum Guide. Free, online, available to everyone, describing the clip-on scaling framework that facilitates employing three to nine Scrum teams (usual) in an integrated effort to develop software.
InfoQ: Scrum is described as a framework, as it contains the basic rules, not practices or tactics to apply within Scrum. Nexus however has been announced as having 40+ practices. Is it then still a framework in the same sense as Scrum is?
Schwaber: These practices and the tools that automate them represent what is needed to run scaled Scrum development projects. The practices and tools are used to describe scaled software development in the Nexus workshop. However, any equivalent practices or tools can be used by the scaled effort. For instance, we have practices for adding attributes to the Product Backlog. Organizations that are using automated requirements tools probably already have an answer to this need that they will employ instead.
InfoQ: What other roles and events, compares to Scrum, were added in Nexus?
Schwaber: A Nexus Integration Team, Product Backlog refinement, Nexus Sprint Planning, Nexus Sprint Goal, Nexus Daily Scrum, Nexus Sprint Review, and Nexus Sprint Retrospective. All resting on and encapsulating similarly named Scrum mechanisms.
InfoQ: Doesn’t these additions confirm that Scrum is not enough in itself?
Schwaber: Confirm that Scrum isn’t enough for what? Developing a self-driving car, developing the next space shuttle? (sarcasm)
Scrum is a very simple framework that describes a one iteration, one increment, one team software development effort. I made no attempt to describe more because I knew that every use would be different and unique. I left the more complex application of Scrum to the user. Indeed, many, many organizations have devised their own processes, standards, frameworks, etc. with which they apply Scrum to a wide-range of development challenges.
However, the appearance of enterprise methodologies such as SAFe and DaD motivated me. Large traditional organizations are purchasing and implementing these methodologies believing that they are silver-bullets, that the money they pay will guarantee a working solution. Unfortunately, these methodologies dump the users into single team Scrum development processes. We have developed Nexus so these large organizations know what to do when their release train (or whatever) gets to software development work.
InfoQ: The Nexus Guide states that "If their primary responsibility is satisfied, Nexus Integration Team Members may also work as Development Team members in one or more Scrum Teams." In agile you normally want to have people full time in one team only. Why does Nexus deviate from this?
Schwaber: We have found that people are more productive when they work full-time on full-time teams. However, we also apply common sense. If the Scrum Teams are very skilled at the scaling requirements of refinement and integration, there is no need for the Nexus Integration Team members to sit around trying to look busy. They are encouraged to be productive.
InfoQ: Projects or products with multiple teams sometimes use a "Scrum of Scrums" to align and synchronize their activities. I don’t see this mentioned in the Nexus Guide, is that on purpose?
Schwaber: Scrum of Scrums was an idea that I put forward in several of my books. It never rose to the status of a Scrum mechanism in the Scrum Guide. The Scrum of Scrums is now subsumed formally in the Nexus Daily Scrum in the Nexus Guide.
InfoQ: Can you elaborate how Nexus supports the alignment of retrospectives and improvement actions over teams?
Schwaber: We run a sandwich. Firstly the Scrum Teams meet and conduct a short retrospective to identify issues that arose while trying to integrate and scale their work. Secondly, members from the Scrum Teams meet with the members of the Nexus Integration Team and conduct a full retrospective, whose primary goal is to identify what needs to be changed in the upcoming Sprint to make the scaling effort more productive and effective. Thirdly, the members of the Scrum Teams go back to their team retrospectives with this information and complete the retrospective.
InfoQ: Are there already organizations adopting Nexus? Do you have some examples and cases?
Schwaber: Yes, it is being used worldwide. We are gathering, editing, and will publish examples and case studies on out website, www.scrum.org, as soon as they are ready. The good, the bad, and the ugly.
InfoQ: Can you describe how Nexus relates to the other scaling approaches that were launched over the past years (SAFe, DAD, LeSS).
Schwaber: Nexus is different both in scope, approach, and cost.
Nexus only addresses scaling software development, starting with a Product Backlog, budget, goal, and scope.
Nexus also is only a framework within which an organizations unique approach to software development operates. Nexus does not guarantee success and is not formulaic. The people doing the software development do so to be successful in the most appropriate manner available. Individuals and interactions over processes and tools.
Oh, also, Nexus is free, available online as the Nexus Guide.
InfoQ: If readers want to know more about Nexus, where can they go?
Schwaber: www.scrum.org, right on the front banners.
