Steve Smith

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Multi-Demand IT

What is Multi-Demand IT? How does it provide the means to drive a Continuous Delivery programme with incremental investments, according to product demand?

This is Part 3 of the Strategising for Continuous Delivery series


Multi-Demand IT is a transformation strategy that recommends investing in groups of technology value streams, according to their product demand. While Bimodal IT recommends upfront, capital investments based on an architectural division of applications, Multi-Demand favours gradual investments in Continuous Delivery across an IT estate based on product Cost of Delay.

A technology value stream is a sequence of activities that converts product ideas into value-adding changes. A demand group is a set of applications in one or more technology value streams, with a shared throughput target that must be met for Continuous Delivery to be achieved. There may also be individual reliability targets for applications within a group, based on their criticality levels.

Uncover demand groups

An IT department should have at least three demand groups representing high, medium, and low throughput targets. This links to Dr. Nicole Forsgren’s research in The Role of Continuous Delivery in IT and Organizational Performance, and Simon Wardley’s Pioneers, Settlers, and Town Planners model in The Only Structure You’ll Ever Need. Additional demand groups representing very high and very low throughput targets may emerge over time. Talented, motivated people are needed to implement Continuous Delivery within the unique context of each demand group.

Multi-Demand creates a Continuous Delivery investment language. Demand groups make it easier to prioritise which applications are in a state of Discontinuous Delivery, and need urgent improvement. The aim is to incrementally invest until Continuous Delivery is achieved for all applications in a demand group.

Applications will rarely move between demand groups. If market disruption or upstream dependents cause a surge in product demand, a rip and replace migration will likely be required as a higher demand group will have its own practices, processes, and tools. When product demand has been filled for an application, its deployment target is adjusted for a long tail of low investment. The new deployment target will retain the same lead time as before, with a lower interval. This ensures the application remains launchable on demand.

A high or medium demand group should contain a single technology value stream. This means all applications with similar demand undergo the same activities and tasks. This reduces cognitive load for teams, and ensures all applications will benefit from a single flow efficiency gain. A low demand group is more likely to have multiple technology value streams, especially if some of its applications are part of a legacy estate.

Example – MediaTech

Assume MediaTech adopts Multi-Demand for its IT transformation. There is a concerted effort to assess technology value streams, and forecast product demand. As a result, the following demand groups are created:

videogames-ui is in the sole Website Services technology value stream, while videogames-data is in one of the Heritage Applications technology value streams.

Create Multi-Demand policies

A demand group will have a policy set which determines its practices, processes, and tools. Inspired by Cynefin, a policy can be a:

  • Policy Fix: single group, such as heightened permissions for teams in a specific group
  • Policy Rule: multi-group single implementation, such as mandatory use of a central incident management system for all groups
  • Policy Guideline: multi-group multi-implementation, such as mandatory test automation with different techniques in each group

A policy will shape one or more activities and tasks within a technology value stream. Each demand group should have a minimal set of policies, as Little’s Law dictates the higher the throughput target, the fewer activities and tasks must exist. Furthermore, applying the Theory Of Constraints to Continuous Delivery shows throughput in a technology value stream will likely be constrained by the impact of a single policy on a single activity.

At MediaTech, the Multi-Demand lens shows videogames-data is in a state of Continuous Delivery while videogames-ui is in Discontinuous Delivery. This is due to the inheritance of End-To-End Testing, CAB meetings, and central production support policies from Heritage Apps, which has lower product demand and a very different context.

Policy Rules should be treated with caution, as they ignore the context and throughput target of a particular demand group. A Policy Rule can easily incur handoffs and rework that constrain throughput in a high demand group, even if it has existed for lower demand groups for years. This can be resolved by turning a Policy Rule into a Policy Guideline, and re-designing an activity per-demand. For example, End-To-End Testing might be in widespread use for all medium and low demand applications. It will likely need to be replaced with Contract Testing or similar with high demand applications.

This is Part 3 of the Strategising for Continuous Delivery series

  1. Strategising for Continuous Delivery
  2. The Bimodal Delusion
  3. Multi-Demand IT
  4. Multi-Demand Architecture
  5. Multi-Demand Operations


Thanks to Thierry de Pauw for reviewing this series.

The Bimodal delusion

Why is Bimodal IT so fundamentally flawed? Why is it just a rehash of brownfield versus greenfield IT? What is the delusion that underpins it?

This is Part 2 of the Strategising for Continuous Delivery series


Bimodal IT is a notoriously bad method of IT transformation. In 2014, Simon Mingay and Mary Mesaglio of Gartner recommended in How to Be Digitally Agile Without Making a Mess that organisations split their IT departments in two. The authors proposed a Mode 1 for predictability and stability of traditional backend applications, and a Mode 2 for exploration and speed of digital frontend services. They argued this would allow an IT department to protect high risk, low change systems of record, while experimenting with low risk, high change systems of engagement.

Example – MediaTech

For example, a MediaTech organisation has an on-premise application estate with separate development, testing, and operations teams. Product stakeholders demand an improvement from monthly to weekly deployments and from 99.0% to 99.9% reliability, so a commitment is made to Bimodal. Existing teams continue to work in the Mode 1 on-premise estate, while new teams of developers and testers start on Mode 2 cloud-based microservices.

This includes a Mode 2 videogames-ui team, who work on a new frontend that synchronously pulls data from a Mode 1 videogames-data backend application.

Money for old rope

Bimodal is a transformation strategy framed around technology-centric choices, that recommends capital investment in systems of engagement only. It is understandable why these choices might appeal to IT executives responsible for large, mixed estates of applications. Saying Continuous Delivery is only for digital frontend services can be a rich source of confirmation bias for people accustomed to modernisation failures.

However, the truth is Bimodal is just money for old rope. The Bimodal division between Mode 1 and Mode 2 is the same brownfield versus greenfield dichotomy that has existed since the Dawn Of Computer Time. Bimodal has the exact same problems:

  • Mode 1 teams will find it hard to recruit and retain talented people
  • Mode 1 teams will trap the domain knowledge needed by Mode 2 teams
  • Mode 2 teams will depend on Mode 1 teams
  • Mode 2 services will depend on Mode 1 applications

The dependency problems are critical. Bimodal architecture is predicated on frontend services distinct from backend applications, yet the former will inevitably be coupled to the latter. A Mode 2 service will have a faster development speed than its Mode 1 dependencies, but its deployment throughput will be constrained by inherited Mode 1 practices such as End-To-End Testing and heavyweight change management. Furthermore, the reliability of a Mode 2 service can only equal its least reliable Mode 1 dependency.

At MediaTech, the videogames-ui team are beset by problems:

  • Any business logic change in videogames-ui requires End-To-End Testing with videogames-data
  • Any failure in videogames-data prevents customer purchases in videogames-ui
  • Mode 1 change management practices still apply, including CABs and change freezes
  • Mode 1 operational practices still apply, such as a separate operations team and detailed handover plans pre-release

As a result, the videogames-ui team are only able to achieve fortnightly deployments and 99.0% reliability, much to the dissatisfaction of their product manager.

The delusion

This is the Bimodal delusion – that stability and speed are a zero-sum game. As Jez Humble explains in The Flaw at the Heart of Bimodal IT, “Gartner’s model rests on a false assumption that is still pervasive in our industry: that we must trade off responsiveness against reliability”. Peer-reviewed academic research by Dr. Nicole Forsgren et al such as The Role of Continuous Delivery in IT and Organizational Performance has proven this to be categorically false. Increasing deployment frequency does not need to have a negative impact on costs, quality, or reliability.

This is Part 2 of the Strategising for Continuous Delivery series

  1. Strategising for Continuous Delivery
  2. The Bimodal Delusion
  3. Multi-Demand IT
  4. Multi-Demand Architecture
  5. Multi-Demand Operations


Thanks to Thierry de Pauw for reviewing this series.

Strategising for Continuous Delivery

What strategy should an IT department adopt to incrementally and iteratively transform itself? How should different methods of software development, testing, and operations be managed at the same time?


Organisations that wish to remain competitive in the years to come must explore new offerings, expand successful differentiators, and exploit established products. A 21st century, digital first organisational model of IT As A Business Differentiator focussed on cloud computing, smart mobile devices, and big data analytics is required.

This is tremendously difficult when an organisation has the 20th century, pre-Internet IT As A Cost Centre organisational model. This refers to disparate Product and IT departments, in which IT is a cost centre with fixed scope, fixed resource, and fixed deadline projects. Segregated development, testing, and operations teams mired in long-term Discontinuous Delivery are ill-equipped to rapidly build and run products.

Strategy is choice

An organisation-wide transformation from IT As A Cost Centre to IT As A Business Differentiator is an arduous, multi-year journey. It is hard to know where to invest in Continuous Delivery when an organisation has a large, mixed estate of well-established on-premise applications and emergent cloud applications. Such applications can act as significant revenue generators, regardless of deployment frequency and runtime environment. This means visionary leadership and a sense of urgency are required from IT executives, and a Continuous Delivery strategy.

A strategy is not a vision, a plan, a list of best practices, or an affirmation of the status quo. A strategy is a unified set of choices including a desire to succeed, a declaration on where to succeed, and a statement of how to succeed. It is a commitment to hard choices, amongst options with asymmetric value.

An effective Continuous Delivery strategy can be used to establish a culture of Continuous Improvement, powered by the Improvement Kata. It allows a programme of radical, far-reaching changes to be built around the choices made. This helps people to understand, and be motivated by changes to how teams work, how they interact, and the processes and tools they use.

On that basis, how can an IT department devise a Continuous Delivery strategy? How can it incrementally and iteratively transform itself?

This is part 1 of the Strategising for Continuous Delivery series

  1. Strategising for Continuous Delivery
  2. The Bimodal Delusion
  3. Multi-Demand IT
  4. Multi-Demand Architecture
  5. Multi-Demand Operations


Thanks to Thierry de Pauw for reviewing this series.

Rebuild The Thing Wrong

What happens when the launch of a software product rebuild is delayed due to feature parity? How can an organisation rebuild a software product the right way, and minimise opportunity costs as well as technology risks?


To adapt to rapidly changing markets, organisations must enhance their established products as well as exploring new product offerings. When the profitability of an existing product is limited by Discontinuous Delivery, a rewrite should be considered a last resort. However, it might become necessary if a meaningful period of code, configuration, and infrastructure rework cannot achieve the requisite deployment throughput and production reliability.

Rebuilding a software product from scratch is usually a costly and risky one-off project, with little attention paid to customer needs. Replicating all the features in an existing product will take weeks or months, and there may be a decision to wait for feature parity before customer launch. It can be a while before Continuous Delivery becomes a reality.

The production cutover will be a big bang migration, with a high risk of catastrophic failure. The probability and cost of cutover failure can be reduced by Decoupling Deploy From Launch, and regularly deploying versions of the new product prior to launch.

The Gamez rebuild

For example, a fictional Gamez retail organisation has an ecommerce website. The website is powered by a monolithic application known as eCom, which is hosted in an on-premise data centre. Recently viewed items, gift lists, search, and customer reviews are features that are often praised by customers, and believed to generate the majority of revenue. eCom deployments are quarterly, production reliability is poor, and data centre costs are too high.

There is a strong business need to accelerate feature delivery, and a rewrite of the Gamez website is agreed. The chosen strategy is a rip and replace, in which the eCom monolith will be rebuilt as a set of cloud-native services, hosted in a public cloud provider. Each service is intended to be an independently testable, deployable, and scalable set of microservices, that can keep pace with market conditions.

There is an agreement to delay customer launch until feature parity is achieved, and all eCom business logic is replicated in the services. Months later, the services are deemed feature complete, the production cutover is accomplished, and the eCom application is turned off.

The feature parity fallacy

Feature parity is a fallacy. Rebuilding a software product with the same feature set is predicated on the absurd assumption that all existing features generate sufficient revenue to justify their continuation. In all likelihood, an unknown minority of existing features will account for a majority of revenue, and the majority of existing features can be deferred or even discarded.

The main motivation for rebuilding a software product is to accelerate delivery, validate product hypotheses, and increase revenues as a result. Waiting weeks or months for feature parity during a rebuild prolongs Discontinuous Delivery, and exacerbates all the related opportunity costs that originally prompted the rewrite.

Back at Gamez, some product research conducted prior to the rebuild is unearthed, and it contains some troubling insights. Search generates the vast majority of website revenue. Furthermore, product videos is identified as a missing feature that would quickly surpass all other revenue sources. This means a more profitable course of action would have been to launch a new product videos feature, replace the eCom search feature, and validate learnings with customers. An opportunity to substantially increase profitability was missed.

Strangler Fig

Rebuilding a software product right means incrementally launching features throughout the rebuild. This can be accomplished with the Strangler Fig architectural pattern, which can be thought of as applying the Expand and Contract pattern at the application level.

Strangler Fig means gradually creating a new software product around the boundaries of an existing product, and rebuilding one feature at a time until the existing product is no more. It is usually implemented by deploying an event interceptor in front of the existing product. New and existing features are added to the new software product as necessary, and user requests are routed between products. This approach means customers can benefit from new features much sooner, and many more learning opportunities are created.

Using the Strangler Fig pattern would have allowed Gamez to generate product videos revenue from the outset. At first, a customer router microservice would have been implemented in front of the eCom application. It would have sent all customer requests to eCom bar product videos, which would have gone to the first microservice. Later on, search and customer review services would have been replaced the same eCom functionality.

Case studies

  1. The Road To Continuous Delivery by Michiel Rook details how Strangler Fig helped a Dutch recruitment company replace its ecommerce website
  2. Strangulation Pattern Of Choice by Joshua Gough describes how Strangler Fig allowed a British auction site to replace its ecommerce website
  3. Legacy Application Strangulation Case Studies by Paul Hammant lists a series of product rewrites made possible by Strangler Fig
  4. How to Breakthrough the Old Monolith by Kyle Galbraith visualises how to slice a monolith up into microservices, using Strangler Fig
  5. Estimation Is Evil by Ron Jeffries mentions how incremental launches would have benefitted the eXtreme Programming (XP) birth project Chrysler C3, rather than a yearlong pursuit of feature parity

Build The Right Thing and Build The Thing Right

Should an organisation in peril start its journey towards IT enabled growth by investing in IT delivery first, or product development? Should it Build The Thing Right with Continuous Delivery first, or Build The Right Thing with Lean Product Development?


The software revolution has caused a profound economic and technological shift in society. To remain competitive, organisations must rapidly explore new product offerings as well as exploiting established products. New ideas must be continuously validated and refined with customers, if product/market fit and repeatable sales are to be found.

That is extremely difficult when an organisation has the 20th century, pre-Internet IT As A Cost Centre organisational model. There will be a functionally segregated IT department, that is accounted for as a cost centre that can only incur costs. There will be an annual plan of projects, each with its scope, resources, and deadlines fixed in advance. IT delivery teams will be stuck in long-term Discontinuous Delivery, and IT executives will only be incentivised to meet deadlines and reduce costs.

If product experimentation is not possible and product/market fit for established products declines, overall profitability will suffer. What should be the first move of an organisation in such perilous conditions? Should it invest first in Lean Product Development to Build The Right Thing, and uncover new product offerings as quickly as possible? Or should it invest in Continuous Delivery to Build The Thing Right first, and create a powerful growth engine for locating future product/market fit?

Build The Thing Right first

In 2007, David Shpilberg et al published a survey of ~500 executives in Avoiding the Alignment Trap in IT. 74% of respondents reported an under-performing, undervalued IT department, unaligned with business objectives. 15% of respondents had an effective IT department, with variable business alignment, below average IT spending, and above average sales growth. Finally, 11% were in a so-called Alignment Trap, with negative sales growth despite above average IT spending and tight business alignment.

Avoiding the alignment trap in IT

Avoiding the Alignment Trap in IT (Shpilberg et al) – source

Shpilberg et al report “general ineffectiveness at bringing projects in on time and on the dollar, and ineffectiveness with the added complication of alignment to an important business objective”. The authors argue organisations that prematurely align IT with business objectives will fall into an Alignment Trap. They conclude organisations should build a highly effective IT department first, and then align IT projects to business objectives. In other words, Build The Thing Right before trying to Build The Right Thing.

The conclusions of Avoiding the Alignment Trap in IT are naive, because they ignore the implications of IT As A Cost Centre. An organisation with ineffective IT will undoubtedly suffer if it increases business alignment and investment in IT as is. However, that is a consequence of functionally siloed product and IT departments, and the antiquated project delivery model tied to IT As A Cost Centre. Projects will run as a Large Batch Death Spiral for months without customer feedback, and invariably result in a dreadful waste of time and money. When Shpilberg et al define success as “delivered projects with promised functionality, timing, and cost”, they are measuring manipulable project outputs, rather than customer outcomes linked to profitability.

Build The Right Thing first

It is hard to Build The Right Thing without first learning to Build The Thing Right, but it is possible. If flow is improved through co-dependent product and IT teams, the negative consequences of IT As A Cost Centre can be reduced. New revenue streams can be unlocked and profitability increased, before a full Continuous Delivery programme can be completed.

An organisation will have a number of value streams to convert ideas into product offerings. Each value stream will have a Fuzzy Front End of product and development activities, and a technology value stream of build, testing, and operational activities. The time from ideation to customer is known as cycle time.

Flow in a value stream can be improved by:

  • understanding the flow of ideas
  • reducing batch sizes
  • quantifying value and urgency

The flow of ideas can be understood by conducting a Value Stream Mapping with senior product and IT stakeholders. Visualising the activities and teams required for ideas to reach customers will identify an approximate cycle time, and the sources of waste that delay feedback. A Value Stream Mapping will usually uncover a shocking amount of rework and queue times, with the majority in the Fuzzy Front End.

For example, a Value Stream Mapping might reveal a 10 month cycle time, with 8 months spent on ideas bundled up as projects in the Fuzzy Front End, and 2 months spent on IT in the technology value stream. Starting out with Build The Thing Right would only tackle 20% of cycle time.

Reducing batch sizes means unbundling projects into separate features, reducing the size of features, and using Work In Process (WIP) Limits across product and IT teams. Little’s Law guarantees distilling projects into small, per-feature deliverables and restricting in-flight work will result in shorter cycle times. In Lean Enterprise, Jez Humble, Joanne Molesky, and Barry O’Reilly describe reducing batch sizes as “the most important factor in systemically increasing flow and reducing variability”.

Quantifying value and urgency means working with product stakeholders to estimate the Cost Of Delay of each feature. Cost Of Delay is the economic benefit a feature could generate over time, if it was available immediately. Considering how time will affect how a feature might increase revenue, protect revenue, reduce costs, and/or avoid costs is extremely powerful. It encourages product teams to reduce cycle time by shrinking batch sizes and eliminating Fuzzy Front End activities. It uncovers shared assumptions and enables better trade-off decisions. It creates a shared sense of urgency for product and IT teams to quickly deliver high value features. As Don Reinertsen says in the The Principles of Product Development Flow, “if you only measure one thing, measure the Cost Of Delay”.

For example, a manual customer registration task generates £100Kpa of revenue, and is performed by one £50Kpa employee. The economic benefit of automating that task could be calculated as £100Kpa of revenue protection and £50Kpa of cost reduction, so £5.4Kpw is lost while the feature does not exist. If there is a feature with a Cost Of Delay greater than £5.4Kpw, the manual task should remain.

Build The Right Thing case study – Maersk Line

Black Swan Farming – Maersk Line by Joshua Arnold and Özlem Yüce demonstrates how an organisation can successfully Build The Right Thing first, by understanding the flow of ideas, reducing batch sizes, and quantifying value and urgency. In 2010, Maersk Line IT was a £60M cost centre with 20 outsourced development teams. Between 2008 and 2010 the median cycle time in all value streams was 150 days. 62% of ~3000 requirements in progress were stuck in Fuzzy Front End analysis.

Arnold and Yüce were asked to deliver more value, flow, and quality for a global booking system with a median cycle time of 208 days, and quarterly production releases in IT. They mapped the value stream, shrank features down to the smallest unit of deliverable value, and introduced Cost Of Delay into product teams alongside other Lean practices.

After 9 months, improvements in Fuzzy Front End processes resulted in a 48% reduction in median cycle time to 108 days, an 88% reduction in defect count, and increased customer satisfaction. Furthermore, using Cost Of Delay uncovered 25% of requirements were a thousand times more valuable than the alternatives, which led to a per-feature return on investment six times higher than the Maersk Line IT average. By applying the same Lean principles behind Continuous Delivery to product development prior to additional IT investment, Arnold and Yüce achieved spectacular results.

Build The Right Thing and Build The Thing Right

If an organisation in peril tries to Build The Right Thing first, it risks searching for product/market fit without the benefits of fast customer feedback. If it tries to Build The Thing Right first, it risks spending time and money on Continuous Delivery without any tangible business benefits.

An organisation should instead aim to Build The Right Thing and Build The Thing Right from the outset. A co-evolution of product development and IT delivery capabilities is necessary, if an organisation is to achieve the necessary profitability to thrive in a competitive market.

This approach is validated by Dr. Nicole Forsgren et al in Accelerate. Whereas Avoiding The Alignment Trap In IT was a one-off assessment of business alignment in IT As A Cost Centre, Accelerate is a multi-year, scientifically rigorous study of thousands of organisations worldwide. Interestingly, Lean product development is modelled as understanding the flow of work, reducing batch sizes, incorporating customer feedback, and team empowerment. The data shows:

  • Continuous Delivery and Lean product development both predict superior software delivery performance and organisational culture
  • Software delivery performance and organisational culture both predict superior organisational performance in terms of profitability, productivity, and market share
  • Software delivery performance predicts Lean product development

On the reciprocal relationship between software delivery performance and Lean product development, Dr. Nicole Forsgren et al conclude “the virtuous cycle of increased delivery performance and Lean product management practices drives better outcomes for your organisation”.

Exapting product development and technology

An organisational ambition to Build The Right Thing and Build The Thing Right needs to start with the executive team. Executives need to recognise an inability to create new offerings or protect established products equates to mortal peril. They need to share a vision of success with the organisation that articulates the current crisis, describes a state of future prosperity, and injects urgency into day-to-day work.

The executive team should introduce the Improvement Kata into all levels of the organisation. The Improvement Kata encourages problem solving via experimentation, to proceed towards a goal in iterative, incremental steps amid ambiguities, uncertainties, and difficulties. It is the most effective way to manage a gradual co-emergence of Lean Product Development and Continuous Delivery.

Experimentation with organisational change should include a transition from IT As A Cost Centre to IT As A Business Differentiator. This means technology staff moving from the IT department to work in long-lived, outcome-oriented teams in one or more product departments, which are accounted for as profit centres and responsible for their own investment decisions. One way to do this is to create a Digital department of co-located product and technology staff, with shared incentives to create new product offerings. Handoffs and activities in value streams will be dramatically reduced, resulting in much faster cycle times and tighter customer feedback loops.

Instead of an annual budget and a set of fixed scope projects, there needs to be a rolling budget that funds a rolling plan linked to desired outcomes and strategic business objectives. The scope, resources, and deadlines of the rolling plan should be constantly refined by validated learnings from customers, as delivery teams run experiments to find problem/solution fit and problem/market for a particular business capability.

Those delivery teams should be cross-functional, with all the necessary personnel and skills to apply Design Thinking and Lean principles to problem solving. This should include understanding the flow of ideas, reducing batch sizes, and the quantifying value and urgency. As Lean Product Development and Continuous Delivery capabilities gradually emerge, it will become much easier to innovate with new product offerings and enhance established products.

It might take months or years of investment, experimentation, and disruption before an organisation has adopted Lean Product Development and Continuous Delivery across all its value streams. It is important to protect delivery expectations and staff welfare by making changes one value stream at a time, by looking for existing products or new product offerings stuck in Discontinuous Delivery.


Thanks to Emily Bache, Ozlem Yuce, and Thierry de Pauw for reviewing this article.

Further Reading

  1. Lean Software Development by Mary and Tom Poppendieck
  2. Designing Delivery by Jeff Sussna
  3. The Essential Drucker by Peter Drucker
  4. Measuring Continuous Delivery by Steve Smith
  5. The Cost Centre Trap by Mary Poppendieck
  6. Making Work Visible by Dominica DeGrandis

IT as a Business Differentiator

How can Continuous Delivery power innovation in an organisation?

When an organisation is in a state of Continuous Delivery, its technology strategy can be described as IT as a Business Differentiator. IT staff will work in one or more product departments, which are accounted for as profit centres in which profits are generated from incoming revenues and outgoing costs. A profit centre provides services to customers, and is responsible for its own investment decisions and profitability.

IT as a Business Differentiator promotes IT to be a front office function. There will be a rolling budget, and a rolling plan consisting of dynamic product areas with scope, resources, and deadlines constantly refined by feedback. Long-lived, outcome-oriented delivery teams will implement experiments to find product/market fit for a particular business capability.

This is in direct contrast to Nicholas Carr’s 2003 proclamation that IT Doesn’t Matter, to which history has not been kind. Carr failed to predict the rise of Agile Development, Lean Product Development, and in particular Cloud Computing, which has commoditised many lower-order technology functions. These advancements have contributed to the ongoing software revolution termed “Software Is Eating The World” by Marc Andreessen in 2011, which has caused a profound economic and technological shift in society.

Continuous Delivery as the norm

IT as a Business Differentiator is an Internet-inspired, 21st century technology strategy in which IT contributes to uncovering new revenue streams that increase overall profitability for an organisation. This means executives and managers are incentivised to maximise revenue generating activities, as well as controlling cost generating activities.

Continuous Delivery is table stakes for IT as a Business Differentiator, as IT executives and managers are accountable for delays between ideation and customer launch. There will be an ongoing investment in technology and organisational change, to ensure deployment throughput meets market demand. There will be a focus on optimising flow by eliminating handoffs, reducing work in progress, and removing wasteful activities. The reliability strategy will be to Optimise For Resilience, in order to minimise failure response time and blast radius.

IT as a Business Differentiator and Continuous Delivery were validated by Dr. Nicole Forsgren et al, in the 2018 book Accelerate. Surveys of 23,000 people working at 2,000 organisations worldwide revealed:

  • Continuous Delivery results in high performance IT
  • High performance IT leads to simultaneous improvements in the stability and throughput of IT delivery, without trade-offs
  • High performance IT means an organisation is twice as likely to exceed profitability, market share, and productivity goals
  • Continuous Delivery also results in less rework, an improved organisational culture, reduced team burnout, and increased job satisfaction

Leaving IT As A Cost Centre

If an organisation has institutionalised IT as a Cost Centre as its technology strategy, moving to IT as a Business Differentiator would be difficult. It would require an executive-level decision, in one of the following scenarios:

  • Competition – rival organisations are increasing their market share
  • Cognition – IT is recognised as the engine of future business growth
  • Catastrophe – a serious IT failure has an enormously negative financial impact

If the executive leadership of the organisation agree there is an existential crisis, they should publicly commit to IT as a Business Differentiator. That should include an ambitious vision of success that explains the current crisis, describes a state of future economic prosperity, and injects a sense of urgency into the day-to-day work of personnel.

There is no recipe for moving from IT as a Cost Centre to IT as a Business Differentiator. As a complex, adaptive system, an organisation will have a dispositional state of time-dependent possibilities, rather than linear cause and effect. A continuous improvement method such as the Improvement Kata should be used to experiment with different changes. Experiments could include:

  • co-locating IT delivery teams with their product stakeholders
  • removing cost accounting metrics from IT executive incentives
  • creating a Digital department of product and IT staff, as a profit centre

This leaves the open question of whether an IT department should adopt Continuous Delivery before, during, or after a move from IT as a Cost Centre to IT as a Business Differentiator.

Further Reading

  1. The Principles Of Product Development Flow by Don Reinertsen
  2. Measuring Continuous Delivery by the author
  3. Lean Enterprise by Jez Humble, Joanne Molesky, and Barry O’Reilly
  4. Utility vs. Strategic Dichotomy by Martin Fowler
  5. Products Not Projects by Sriram Narayan


Thanks to Thierry de Pauw for his feedback.

IT as a Cost Centre

Why does Continuous Delivery encounter resistance from IT executives and managers in so many organisations, and why is it so difficult to implement? Why does IT as a Cost Centre results in long-term Discontinuous Delivery?


When an organisation is in a state of Discontinuous Delivery, its organisational model can usually be described as IT as a Cost Centre. There will be a functionally segregated IT department, that is accounted for as a cost centre in which costs can be incurred but profits cannot be generated. The IT department will provide services to product departments, which are accounted for as profit centres responsible for investment decisions and profitability.

IT as a Cost Centre relegates IT to a back office function. Each year, the IT department will be allocated a fixed budget to deliver a set of projects required by the product departments. Each project will represent a large batch of pre-agreed requirements. Short-lived project teams will try to deliver those requirements with scope, resources, and deadlines all fixed in advance.

This dovetails with the traditional view of IT as a universal commodity, popularised by Nicholas Carr in IT Doesn’t Matter in 2003. Carr argued IT was merely an infrastructural technology, and concluded it was merely a cost of doing business that could not provide a sustained competitive advantage.

Cost accounting suzerainty

IT as a Cost Centre is a pre-Internet organisational model from the mid-20th century, that still persists today. The world is now reliant on, and connected by technology, yet in a 2014 survey of 700+ organisations by CIO 48% of organisations still had IT as a cost centre.

In The Cost Centre Trap, Mary Poppendieck traces the popularity of IT cost centres back to the ubiquity of cost accounting. Poppendieck describes how the performance of an IT cost centre is measured solely in terms of cost management. This means accounting metrics percolate into the performance metrics of IT executives and managers, creating a culture of cost control with little regard for product development or organisational performance. These incentives will be markedly different to those of product executives and managers, and usually contribute to an adversarial relationship between product departments and IT.

In cost accounting, inventory is tracked as an asset, maximum resource utilisation is encouraged, and development work is capitalised until production launch. These factors create a hidden bias towards the institutionalisation of large projects, due to their perceived economies of scale. In reality, the project delivery model is an ineffective, inefficient vehicle that impedes value, quality, and flow.

Discontinuous Delivery as the norm

A Continuous Delivery programme is an unending journey of continuous improvement, that requires a substantial investment in order to achieve a time to market that can improve product/market fit and increase revenues.

This is likely to be a hard sell in an organisation with IT as a Cost Centre. IT executives and managers will be incentivised to reduce costs wherever possible, while delivering projects that are supposedly on time, on scope, and on budget. As a result, there will be resistance to the idea of spending money on an internal programme with an explicit goal of improving organisational performance and no fixed end date.

Delivery teams will be short-lived, which encourages people to prioritise short-term feature work over long-term architectural work, which restricts the deployability and testability of different services. The reliability strategy will be to Optimise For Robustness, which increases lead times and failure blast radius. Furthermore, the lack of a mandate beyond development work will make it difficult to work with operations teams to establish consistent toolchains for deployments, logging, monitoring, and alerting.

In short, Dr. Eli Goldratt was right when he said in The Goal “if it comes from cost accounting, it must be wrong”.

Further Reading

  1. The Principles Of Product Development Flow by Don Reinertsen
  2. Measuring Continuous Delivery by the author
  3. Lean Enterprise by Jez Humble, Joanne Molesky, and Barry O’Reilly
  4. Utility vs. Strategic Dichotomy by Martin Fowler
  5. No Projects by the author


Thanks to Thierry de Pauw for his feedback

Deployment pipeline design and the Theory Of Constraints

How should you design a deployment pipeline? Short and wide, long and thin, or something else? Can you use a Theory Of Constraints lens to explain why pipeline flexibility is more important than any particular pipeline design?


  • Past advice from the Continuous Delivery community to favour short and wide deployment pipelines over long and thin pipelines was flawed
  • Parallelising activities between code commit and production in a short and wide deployment pipeline is unlikely to achieve a target lead time 
  • Flexible pipelines allow for experimentation until a Goldilocks deployment pipeline can be found, which makes Continuous Delivery easier to implement


The Deployment Pipeline pattern is at the heart of Continuous Delivery. A deployment pipeline is a pull-based automated toolchain, used from code commit to production. The design of a deployment pipeline should be aligned with Conway’s Law, and a model of the underlying technology value stream. In other words, it should encompass the build, testing, and operational activities required to launch new product ideas to customers. The exact tools used are of little consequence.

Advice on deployment pipeline design has remained largely unchanged since 2010, when Jez Humble recommended “make your pipeline wide, not long… and parallelise each stage as much as you can“. A long and thin deployment pipeline of sequential activities is easy to reason about, but in theory parallelising activities between build and production will shorten lead times, and accelerate feedback loops. The trade-off is an increase in toolchain complexity and coordination costs between different teams participating in the technology value stream.

For example, imagine a technology value stream with sequential activities for automated acceptance tests, exploratory testing, and manual performance testing. This could be modelled as a long and thin deployment pipeline.

If those testing activities could be run in parallel, the long and thin deployment pipeline could be re-designed as a short and wide deployment pipeline.

Since 2010, people in the Continuous Delivery community – including the author – have periodically recommended short and wide deployment pipelines over long and thin pipelines. That advice was flawed.

The Theory Of Constraints, Applied

The Theory Of Constraints is a management paradigm by Dr. Eli Goldratt, for improving organisational throughput in a homogeneous workflow. A constraint is any resource with capacity equal to, or less than market demand. Its level of utilisation will limit the utilisation of other resources. The aim is to iteratively increase the capacity of a constraint, until the flow of items can be balanced according to demand. The Theory Of Constraints is applicable to Continuous Delivery, as a technology value stream should be a homogeneous workflow that is as deterministic and invariable as possible.

When a delivery team is in a state of Discontinuous Delivery, its technology value stream will contain a constrained activity with a duration less than the current lead time, but too large for the target lead time. The duration might be greater than the target lead time, or the largest duration of all the activities. A short and wide deployment pipeline will not be able to meet the target lead time, as the duration of the parallel activities will be limited by the constrained activity.

In the above example, assume the current lead time is 14 days, and manual performance testing takes 12 days as it involves end-to-end performance testing with a third party.

Assume customer demand results in a target lead time of 7 days. This means the delivery team are in a state of Discontinuous Delivery, and a long and thin deployment pipeline would be unable to meet that target.

A short and wide deployment pipeline would also be unable to achieve the target lead time. The parallel testing activities would be limited by the 12 days of manual performance testing, and future release candidates would queue before the constrained activity. An obvious countermeasure would be for some release candidates to skip manual performance testing, but that would increase the risk of production incidents.

This means long and thin vs. short and wide deployment pipelines is a false dichotomy.

Pipeline Design and The Theory Of Constraints

In The Goal, Dr. Eli Goldratt describes the Theory Of Constraints as an iterative cycle known as the Five Focussing Steps: identify a constraint, reduce its wasted capacity, regulate its item arrival rate, increase its capacity, and then repeat.

If the activities in a technology value stream can be re-sequenced, re-designing a deployment pipeline is one way to reduce wasted time at a constrained activity, and regulate the arrival of release candidates. Pipeline flexibility is more important than any particular pipeline design, as it enables experimentation until a Goldilocks deployment pipeline can be found.

The constrained activity should not be the first activity after release candidate creation. This would reduce subsequent release candidate queues, and statistical fluctuations in unconstrained activities. However, constraint time should never be wasted on items with knowable defects, and most activities in a deployment pipeline are testing activities.

One Goldilocks deployment pipeline design is for all unconstrained testing activities to be parallelised before the constrained activity. This should be combined with other experiments to save constraint time, and regulate the flow of release candidates to minimise queues and statistical fluctuations. Such a pipeline design will make it easier for delivery teams to successfully implement Continuous Delivery.

In the above example, assume the short and wide deployment pipeline can be re-designed so manual performance testing occurs after the other parallelised testing activities. This ensures release candidates with knowable defects are rejected prior to performance testing, which saves 1 day in queue time per release candidate. End-to-end performance testing scenarios are gradually replaced with stubbed performance tests and contract tests, which saves 6 days and means the target lead time can be accomplished. 

If there is no constrained activity in a technology value stream, the delivery team is in a state of Continuous Delivery and a constraint will exist either upstream in product development or downstream in customer marketing. Further deployment pipeline improvements such as automated filtering of test scenarios could increase the speed of release candidate feedback, but the priority should be tackling the external constraint if product cycle time from ideation to customer is to be improved.


Thanks to Thierry de Pauw for his feedback on this article.

Continuous Delivery and the Theory Of Constraints

How should you actually implement Continuous Delivery?

Adopting Continuous Delivery takes time. You have a long list of technology and organisational changes to consider. You have to work within the unique circumstances of your organisation. You’re constantly surrounded by strange problems, half-baked theories, off the shelf solutions that just don’t work, and people telling you Amazon is nothing to worry about

How do you identify and remove the major impediments in your build, testing, and operational activities? How do you avoid spending weeks, months, or years on far-reaching changes that ultimately have no impact on your time to market?


  • Continuous Delivery means applying technology and organisational changes to the unique circumstances of an organisation
  • If a Continuous Delivery programme does not focus on the activities with the most rework and/or queue times, there is a high probability of sub-optimal outcomes
  • The Theory Of Constraints is a management paradigm for improving organisational throughput, while simultaneously decreasing both inventory and operating expense.
  • The Theory Of Constraints can be applied to Continuous Delivery, as the build, testing, and operational activities in a technology value stream should be homogeneous
  • The Five Focussing Steps can be used to identify constrained activities, and then introduce the necessary technology and organisational changes to reduce rework and/or queue times


Technology can bring benefits if, and only if, it diminishes a limitation – Dr. Eli Goldratt

An organisation will have one or more technology value streams. Each one will represent a sequence of activities that converts business ideas into value-adding software for customers. The first part of a technology value stream will be design and development activities, which are inherently non-deterministic and highly variable. The second part will be build, testing, and operational activities, which should be as deterministic and invariable as possible. When an organisation lacks the necessary stability and throughput in its technology value streams to satisfy market demand, it is in a state of Discontinuous Delivery.

Continuous Delivery is a set of holistic principles and practices to improve the stability and throughput of IT delivery. It needs a substantial investment in technology changes:

  • Version Control: put code, configuration, infrastructure definitions, migration scripts, etc. in version control to preserve change history
  • Environments: automate self-service, on-demand provisioning of short-lived test environments and incremental release patterns such as Canary Deployments
  • Development: use Test Driven Development with Pair-Programming to build quality into a codebase, and use Trunk Based Development with Continuous Integration to ensure it is always releasable
  • Architecture: establish an Evolutionary Architecture to encourage loosely-coupled, independently deployable services
  • Testing: automate parallelisable acceptance tests with dynamic test data, use Smoke Testing to validate deployments, and use Exploratory Testing to uncover new information
  • Operability: aggregate logs and metrics to create a centralised telemetry platform for visualising normal conditions, and alerting on abnormal conditions

It also requires a significant amount of organisational changes:

  • Batch Size: reduce features per release candidate to decrease variability, feedback delays, risk, overheads, inefficiencies, and lead time via Little’s Law
  • Management: devolve decision making to the employees closest to the work to empower better choices in design, testing etc.
  • Culture: grow a performance-oriented culture of cooperation and collaboration to increase information flow between teams
  • Responsibilities: change responsibilities for testing and on-call production support to encourage a shared sense of accountability
  • Risk: use continuous code reviews via Pair-Programming and traceability of production changes to replace Risk Management Theatre with adaptive risk assessment
  • Skills: invest in employee training to ease the introduction of new practices and tools e.g. infrastructure automation
  • Structures: convert siloed functional teams into cross-functional teams, and align team and software architecture with Conway’s Law to enable faster delivery

These changes are challenging in isolation, but it is their application to the unique circumstances and constraints of an organisation that makes Continuous Delivery so difficult. Adopting Continuous Delivery means implementing widespread changes in the highly uncertain conditions of a complex, adaptive system, in which behaviours are emergent and interactions are unpredictable.

A Continuous Delivery programme should aim to reduce rework and queue times in a technology value stream, as they are the most common sources of waste. Rework is any activity that must be repeated due to a failure, such as a tester being given a defective release candidate. Queue time is time spent queuing for an activity, such as a deployment waiting for a tester to become available. There are many potential causes of rework and queue time, including the following:

Cause Description
Snowflake environments Manual environment provisioning
Brittle deployments Unreliable code, config, or infra changes
Environment contention Slow access to test data, services, or environments
End-To-End Testing Reams of slow, non-deterministic tests
Rigid architecture Application deployments coupled together
Excessive toil Manual, repetitive build/testing/operations tasks

Over the years, the advice on how to implement Continuous Delivery has evolved. The Continuous Delivery book suggested using the Plan-Do-Check-Act Cycle to experiment with changes, and implement a maturity model. Lean Enterprise recommended the Improvement Kata be used to create a Continuous Improvement framework, with Plan-Do-Check-Act used to structure different experiments. This can be very effective, but there needs to be a way to focus on the activities where a reduction in rework and/or queue times will have an immediate, positive impact. Otherwise, there is a high probability of sub-optimal outcomes, stakeholder dissatisfaction, and Discontinuous Delivery remaining the norm.

Given sufficient Continuous Delivery expertise, heuristics can be used to locate those activities in a technology tech value stream. An alternative method is needed when those heuristics are unavailable, or insufficient to overcome resistance to change.

Example – Network Activation

Think of an 18 month Continuous Delivery programme for a multi-team, multi-application Network Activation platform. The delivery teams already use Pair-Programming, Test-Driven Development, Trunk Based Development, and Continuous Integration. The on-prem technology value stream has 2 pre-production activities – Functional Test and Integration Test – and a production deployment involves 10 semi-automated and manual tasks. Problems include snowflake environments, brittle deployments, and End-To-End Testing. There is no data on deployments, beyond an average lead time to production of 34 days. The product owner wants it to be 14 days.

Over 18 months there is a concerted effort to create a consistent deployment pipeline, with the Cost of Delay used to prioritise pipeline features. Aggregate Artifacts and Artifact Containers are used to automate deployments, infrastructure provisioning errors are eliminated, and pipeline dashboards are built. Verify Branch By Abstraction is used to incrementally decouple applications, by replacing object serialisation with RESTful APIs. API Examples and Consumer Driven Contracts are used to verify application interactions. There are also a series of organisational changes to policies, processes, and teams, to reduce queue time for Functional Test and Integration Test.

These changes produce many benefits, including a 95% build time improvement from 1 hour to 3 minutes, and a 43% improvement in test deployment time from 3.5 hours to 2.5 hours. However, there is no impact whatsoever on the average lead time of 34 days. On that basis, the Continuous Delivery programme is unsuccessful.

The Theory Of Constraints

In The Goal, Dr. Eli Goldratt sets out the Theory Of Constraints. The Theory Of Constraints is a management paradigm for improving organisational throughput, by optimising a small number of constraints in a homogeneous workflow. It states the goal of an organisation is to make money, by increasing throughput while simultaneously decreasing both inventory and operating expense.

A constraint is any resource with capacity equal to or less than market demand, and it will limit the throughput of the organisation. A constraint is internal when market demand is greater than throughput, and external when throughput is greater than market demand. An hour lost at a constraint is an hour lost for the whole organisation.

A non-constraint is any resource with capacity greater than market demand. The level of utilisation of a non-constraint is determined by a constraint elsewhere. An increase in non-constraint capacity is a waste of time and money, as it can only increase queued work before a constraint and cannot reduce work starvation after a constraint. An hour lost at a non-constraint is an illusion.

The central premise of the Theory Of Constraints is to iteratively increase the capacity of a constraint, until the flow of work items can be balanced according to market demand. The Five Focussing Steps are used to achieve this:

  1. Identify the constraint(s): calculate market demand for a product, and which activities have capacity less than or equal to demand
  2. Exploit the constraint(s): increase constraint utilisation by eliminating idle time, and time wasted on lower priority and/or defective work items
  3. Subordinate everything else to the constraint(s): protect a constraint from excessive inventory or work starvation by maintaining a buffer of materials, and regulating the arrival of new work items into the system based on constraint capacity
  4. Elevate the constraint(s): offload constraint work items to a non-constraint by investing in additional equipment, people, and/or allocation of work items to third parties
  5. If a constraint has been broken, go back to step 1, but do not allow inertia to cause a constraint

Continuous Delivery and the Theory Of Constraints

The Theory Of Constraints can be applied to Continuous Delivery, as the build, testing, and operations activities in a technology value stream should be homogeneous. There will be one, or at most a few constrained activities, caused by rework and/or queue times. The Five Focussing Steps can be used to identify and optimise the constraint(s), until the flow of release candidates is balanced from mainline commit to production and Continuous Delivery is achieved. At that point, an external constraint will emerge upstream in product development or downstream in sales. If market demand increases later on, a new internal constraint might surface within the technology value stream.

Identify the constraint

A constraint is identified by establishing the market demand for a product, and then calculating how much time each activity contributes to meeting that demand. Overall market demand should be specified by the product owner as a target Lead Time lt, and measured from mainline commit to production launch.

lt = X minutes/hours/days

The ability of an activity a n to meet lt should be expressed as its Activity Time at n. It can be measured as the median between its finish time aft n and the finish time of the prior activity aft n – 1, for all occurrences of a n in a time period t. This measurement ensures queue time and process time are both accounted for. The measurement unit should be minutes, hours, or days based on lt. It might be necessary to measure variability in Activity Time as well, if one or more activities exhibit an undesirable amount of variability.

at n = median ( ( aft n - aft n - 1 ) for a n in t )

If an activity has at n greater than lt, it is a constraint. If a high percentage of release candidates consistently fail to pass the activity on the first attempt, it is unstable and rework must be reduced. Alternatively, if release candidates are regularly delayed before starting the activity, it is too slow to begin and queue time must be reduced.

If no activity has at n greater than lt, there is no internal constraint. This means lt is not ambitious enough, or there is an external constraint outside the technology value stream.

Applying the Theory Of Constraints to the Network Activation platform with its target lead time of 14 days reveals a constraint. Visualising each activity as queue time and process time shows Production queue time was often greater than 14 days. This was caused by a well-intentioned release management policy of deploying release candidates into production when ready, and then waiting for a launch date pre-agreed with an upstream billing provider months earlier. Launch dates were delayed when testing finished late, but never brought forward when testing finished early. 18 months of hard work reduced variability, Functional Test queue time, and Integration Test queue time, but those improvements merely led to an increase in Production queue time until launch dates occurred.

Optimise the constraint

A constraint is optimised by experimenting with the full range of technology and organisational changes recommended by Continuous Delivery. There needs to be a concerted effort to reduce the average and variation in Activity Time for the constrained activity, until the target Lead Time can be satisfied.

Exploiting a constrained activity means ensuring it is always working, and always doing valuable work. This aligns with Continuous Delivery emphasising the automation of repetitive tasks to free up people for higher-order problems. Automated infrastructure provisioning, automated unit and acceptance testing, and moving to an Evolutionary Architecture are all examples of technology changes to reduce time spent at a constrained activity. The most effective organisational change is to reduce batch sizes, as a smaller batch will have shorter process times and queue times.

Subordinating unconstrained activities means limiting the flow of mainline commits, builds, and deployments to match the constrained activity. This is best accomplished with Work In Process (WIP) Limits, which encourage people to collaborate on a few work items at any point in time. Stop The Line teaches people to prioritise a releasable codebase over developing more features, and eXtreme Programming practices such as Test-Driven Development and Pair-Programming can also foster a shared team cadence.

Elevating a constrained activity means investing in people and tools to increase its capacity. This might be achieved with technology changes, such as a move to short-lived test environments via fully automated infrastructure provisioning. It might also involve organisational changes such as paying third party suppliers for more test data, hiring more engineers, or running training courses to improve Staff Liquidity.

For instance, an assortment of changes should be tried if End-To-End Testing activity is a constraint. Time wasted should be eliminated by ensuring testers are uninterruptible, making more testers available, and running testing slots 24 hours a day. Defective release candidates should be minimised by moving all other testing activities in front of End-To-End Testing, adding automated contract tests, and rejecting release candidates with one or more test failures. Over time the end-to-end tests should be incrementally replaced with automated acceptance tests, monitoring dashboards, and automated anomaly detection.

Example: MediaTech

Consider a 7 month Continuous Delivery programme for a multi-team, multi-application MediaTech platform. The delivery teams use Trunk Based Development with some Pair Programming, but there is little Test-Driven Development. The on-prem technology value stream has 2 pre-production activities – Functional Test and Release Test – and a production deployment involves 60 semi-automated and manual tasks. Problems include snowflake environments, brittle deployments, environment contention, a rigid architecture, End-To-End Testing, and excessive toil. There is no data on deployments, beyond an average interval of 3 weeks. The product owner has set a target lead time of 1 week, at an interval of 1 week.

The range of problems at MediaTech makes Continuous Delivery very challenging. There is a proposal to create a fully automated deployment pipeline, with infrastructure provisioning, deployments, and telemetry. Other suggested options include the promotion of Test-Driven Development, implementing zero downtime deployments, and immutable release candidates. However, there are concerns about the time needed to make such changes.

After 2 months, deployment data is scraped from chat channels, and applying the Five Focussing Steps shows sweeping changes are not immediately required. The constraint on a target lead time of 1 week is Release Test process time, due to perennial environment instability caused by configuration and test data issues. Interestingly, there is no obvious constraint on a target lead time of 2 weeks. As a result, the product owner agrees to a target lead time of 2 weeks at an interval of 2 weeks, as an intermediate milestone.

In the Theory Of Constraints, a lack of skilled people can constitute a constraint. When the above data is shared with the MediaTech operations team, they reveal an unseen constraint on the 14 day target lead time. There is a single release planner, who endures a heavy workload for each production deployment on top of their day to day work. Everyone agrees the Continuous Delivery programme needs to focus on automating the release planning tasks, and improving the existing automated tests.

Over the next few months, the release planning workload is reduced and the automated tests are stabilised. Callout rota emails by the release planner are replaced by a shared rota, co-owned by the delivery teams. A release note process overseen by the release planner involving 3 different teams is replaced by a fully automated release note tool. Furthermore, end-to-end tests in Integration Test and Release Test are prioritised by their non-determinism, and gradually rewritten as build-time acceptance tests. The target lead time of 2 weeks at an interval of 2 weeks is successfully achieved, and after several production deployments the product owner decides the new throughput is sufficient. The Continuous Delivery programme is considered a success, and without a fully automated deployment pipeline.

Further Reading

  1. Beyond The Goal by Dr. Eli Goldratt
  2. Measuring Continuous Delivery by the author
  3. Resilience as a Continuous Delivery Enabler by the author


Thanks to Thierry de Pauw for his feedback on this article.

Resilience as a Continuous Delivery enabler

Why does optimising for robustness leave organisations in a state of Discontinuous Delivery, and vulnerable to failure? How does optimising for resilience improve reliability, and how can it encourage the adoption of Continuous Delivery?

The Resilience as a Continuous Delivery Enabler series:

  1. The cost and theatre of Optimising For Robustness
  2. When Optimising For Robustness fails
  3. The value of Optimising For Resilience
  4. Resilience as a Continuous Delivery enabler


  • Optimising For Robustness – prioritising MTBF over MTTR – is an antiquated, flawed approach to IT reliability that results in Discontinuous Delivery and an operational brittleness that begets failure
  • If an organisation has previously optimised for robustness, a Continuous Delivery programme focussed on throughput is unlikely to succeed
  • Optimising For Resilience – prioritising MTTR over MTBF – is a superior reliability strategy that enables an organisation to gracefully extend to limit the impact of failures, and position itself for sustained adaptability
  • Resilience As A Continuous Delivery Enabler is a heuristic that advocates resilience as the focus of a Continuous Delivery programme
  • Improving the resilience of services makes it easier to reduce Risk Management Theatre, and gradually adopt Continuous Delivery

The tradition of robustness

As software continues to eat the world, organisations must have reliable IT services at the heart of their business if they are to innovate in rapidly changing markets. Reliability is defined by Patrick O’Connor and Andre Kleyner in Practical Reliability Engineering as “the probability that [a system] will perform a required function without failure under stated conditions for a stated period of time“, or as a function of Mean Time Between Failures (MTBF) and Mean Time To Repair (MTTR).

The traditional IT reliability strategy is Optimising For Robustness. This means prioritising a higher MTBF over a lower MTTR for IT services, by attempting to maintain a failure-free production environment. It is based on the belief that a production environment is a complicated system, in which services are homogeneous processes with predictable interactions in repeatable conditions. Failures are believed to be caused by isolated, faulty changes and are considered entirely preventable. When an organisation optimises for robustness, it will usually rely upon:

  • End-To-End Testing to verify the functionality of a new service version against its unowned dependent services
  • Change Advisory Boards to assess, prioritise, and approve the deployment of new service versions
  • Change Freezes to restrict the deployment of new service versions for a period of time due to market conditions

These practices are inherently slow, and a form of Risk Management Theatre 1. End-To-End Testing incurs long execution times and significant maintenance time, and defects can still occur. Change Advisory Boards involve slow approval times, and deployments can still fail. Change Freezes cause huge productivity impediments, and failures can still happen. In addition, the long deployment lead times caused by robustness practices ensure a large batch of requirements and technology changes per release, which actually increases the risk of failure 2.

Optimising For Robustness constrains the stability and throughput of IT delivery such that business demand cannot be satisfied. It is the predominant reason why so many organisations are trapped in a state of Discontinuous Delivery.

The constancy of failure

Ironically, Optimising For Robustness leaves an organisation ill-equipped to deal with failure. In Resilience and Precarious Success, Mary Patterson and Robert Wears describe how “fundamental goals (such as safety) tend to be sacrificed with increasing pressure to achieve acute goals (faster, better, and cheaper)“. When an organisation optimises for robustness it will under-invest in its production environment, resulting in unimplemented “non-functional” requirements, inadequate telemetry 3, snowflake infrastructure, and a fragile service architecture. This will be considered acceptable, as failures are expected to be rare.

However, it is naive to think of a production environment of running services as a complicated system. A production environment is an intractable mass of heterogeneous processes, with unpredictable interactions occurring in unrepeatable conditions. It is a complex system of emergent behaviours, in which the cause and effect of an event can only be perceived in retrospect. Furthermore, as Richard Cook explains in How Complex Systems Fail the complexity of these systems makes it impossible for them to run without multiple flaws“. A production environment is perpetually in a state of near-failure.

A failure occurs when multiple faults unexpectedly coalesce such that one or more business operations cannot succeed. It will create a revenue cost expressed as a function of cost per unit time and duration, and in an organisation optimised for robustness the impact can be considerable. The sunk cost incurred until failure detection can be high, as unimplemented “non-functional” requirements and inadequate telemetry will restrict situational awareness. The opportunity cost until failure resolution can also be high, as snowflake infrastructure and a fragile architecture will increase failure blast radius. In addition, the loss of customer confidence and increased failure demand will create further opportunity costs.

Consider a Fruits-U-Like website optimised for robustness. Its third party registration service begins to suffer under load, and new customers are rejected on checkout. The failure has a static cost per day of £80k, but with no telemetry the failure is not detected for 3 days. The checkout team then produces a hotfix within a day, and it is deployed the following day. The revenue cost is £400K, with a £240K sunk cost and a £160K opportunity cost.

Optimising For Robustness encourages an attitude Sidney Dekker calls the Bad Apple Theory, in which a system is considered absolutely reliable except for the actions of unreliable employees. When a failure occurs, the combination of the Bad Apple Theory and hindsight bias will produce an oppressive culture of naming, blaming, and shaming the individuals involved. This discourages knowledge sharing and collaboration.

An interesting consequence of Optimising For Robustness is Dual Value Streams. An organisation optimised for robustness will have feature value streams with deployment lead times of weeks or months. When a failure is detected its sunk cost will create urgency, and people will want to immediately minimise the opportunity cost duration. That will lead to robustness practices being sacrificed for speed, in a truncated fix value stream with an MTTR of hours or days 4. The robustness practices omitted from the fix value stream should be considered theatre until proven otherwise.

Continuous Delivery improves the stability and throughput of IT delivery, but it is hard. A Continuous Delivery programme in an organisation optimised for robustness will not succeed if it is focussed solely on throughput. The most significant accelerator of deployment lead time will likely be the removal of robustness risk management theatre, but practices like End-To-End Testing will be woven into the fabric of the organisation 5. If they are forcibly removed, Continuous Delivery will be blamed for the first subsequent production failure. Resisters will lobby for more robustness practices, and a return to the status quo is all but inevitable. Unfortunately, it only takes one inopportune failure for a Continuous Delivery programme to be cancelled.

The value of resilience

A far more effective reliability strategy is Optimising For Resilience. This means prioritising a lower MTTR over a higher MTBF for IT services, by rapidly responding to failures in a production environment. Some classes of failure should never occur, some failures are more costly than others, and some safety-critical systems should never fail, but in general organisations should adhere to John Allspaw’s advice that “being able to recover quickly from failure is more important than having failures less often“.

Resilience can be thought of as graceful extensibility. In Four Concepts for Resilience and their Implications for Systems Safety in the Face of Complexity, David Woods describes graceful extensibility as “the ability of a system to extend its capacity to adapt when surprise events challenge its boundaries“. The graceful extensibility of a system is derived from its adaptive capacity, which represents the capacity for adaptation when a failure occurs.

Erik Hollnagel et al break down resilience in Resilience Engineering In Practice using a conceptual model known as the Four Cornerstones of Resilience:

The cornerstones are non-linear, complementary aspects of resilience:

  • Anticipation is imagining the potential for future failures, and countering those scenarios in advance
  • Monitoring is inspecting operating conditions, and alerting when anomalies occur
  • Response is using guidelines, heuristics, improvisation, and situational awareness to mitigate a failure
  • Learning is understanding the circumstances of a near-miss or failure, and sharing the observations

Optimising For Resilience means creating a production environment in which running IT services can gracefully extend to deal with the unpredictable behaviours, unexpected changes, and periods of failure that will inevitably occur. When a service has sufficient adaptive capacity the cost per unit time and duration of production failures can potentially be minimised, reducing the direct revenue costs and indirect opportunity costs caused by a failure.

A lower MTTR can be achieved by investing in the operability of IT services. Operability is defined as “the ability to keep a system in a safe and reliable functioning condition“, and is associated with a set of practices:

Each of these will increase the capacity of a service to adapt to unexpected operating conditions, and produce a more effective incident response:

  • Development: an Adaptive Architecture limits the blast radius of a failure, and Feature Toggles allow features to be limited, tested in isolation, or turned off on failure
  • Testing: Smoke Testing verifies service health, and Chaos Engineering uncovers latent failures in production
  • Infrastructure: Automated Provisioning creates reproducible environments, and Self-Healing automatically restores failed service instances
  • Telemetry: Logging radiates data on traffic, errors, latency, and saturation, and Monitoring visualises service metrics and events in a time series. Anomaly detection identifies events that breach normal operating conditions and Alerting notifies operators of abnormalities to act on. User analytics show success rates for user journeys
  • People: Shared On-Call fosters a “You Build It, You Run It” culture and increases situational awareness, and Runbooks are a repository for operational knowledge. Blameless Post-Mortems uncover the multiple contributors to a near-miss or failure and suggest future preventative measures, while respecting the best efforts of individuals and the dangers of hindsight bias 1

If Fruits-U-Like was optimised for resilience its checkout team could receive an alert within 5 minutes of third party registration errors. A Circuit Breaker would allow some registrations to succeed, and a Bulkhead could trigger an anonymous checkout for failed registrations. This could decrease the cost per day to £5K, and a hotfix could be deployed within 3 hours. The revenue cost would be £625, with a £18 sunk cost and a £607 opportunity cost.

Optimising For Resilience sets the foundation for an organisation to act on market disruption and innovate. Once an organisation has the required level of graceful extensibility, it can continue to invest in its people and technology to achieve sustained adaptability. Sustained adaptability has been described by David Woods as “the ability to adapt to future surprises as conditions continue to evolve“, and can be thought of as innovation capability. An organisation that can quickly adapt to unexpected business events will hold a powerful First Mover Advantage over its competitors.

Resilience as a Continuous Delivery enabler

There is no recipe for success with Continuous Delivery, as every organisation is a complex, adaptive system with its own circumstances and constraints. However, if an organisation has previously optimised for robustness and is in a state of Discontinuous Delivery there is a heuristic that can be used:

Resilience as a Continuous Delivery enabler

This can be applied to bootstrapping Continuous Delivery:

This bootstrap sequence can guide the formative steps of a Continuous Delivery programme, and build confidence throughout an organisation. It demonstrates a commitment to stability, transparency, and reliability which will help to win over resisters. Storing all code, configuration, infrastructure definitions, documents, scripts etc. in version control eliminates the predominant source of failure demand. Creating stability and throughput indicators helps people to understand their delivery capabilities, and make better decisions 7.

Improving production reliability minimises the cost of failure, and lays the groundwork for challenging robustness risk management theatre later on. Automated anomaly detection and alerting will speed up the detection time of an anticipated failure, reducing its sunk cost duration to seconds or minutes. An adaptive architecture will limit the blast radius of a failure, decreasing both cost per unit time and duration.

Implementing production telemetry early on also provides insurance for unsafe-to-fail situations. Logging, monitoring, and analytics dashboards can identify the contributing technical faults to a failure, and when they first entered production. If resisters blame Continuous Delivery for a failure, the data will pinpoint which faults were recent and which were lying dormant in production beforehand.

Once the Continuous Delivery programme reaches the experimentation phase, other sources of adaptive capacity can be created with operability practices such as Capacity Planning, Self-Healing, Shared On-Call, and Blameless Post-Mortems. At the same time, the programme should widen its focus to include deployment throughput as well as deployment stability and production resilience.

The end of theatre

The key to removing robustness risk management theatre is to visualise its costs to stakeholders and offer a practical alternative, rather than rely on theoretical arguments about wait times or defect discovery rates. Using the Resilience As A Continuous Delivery Enabler heuristic ensures a Continuous Delivery programme can supply those visualisations, and outline an alternative approach from the outset.

Stakeholders should be made aware of their robustness risk management theatre with a showcase of the delivery awareness and production reliability improvements so far. The stability and throughput indicators will illustrate the historical cost of robustness practices, by visualising the disparity between deployment lead times and MTTR in the Dual Value Streams. Some carefully calibrated Chaos Engineering in a test environment 8 will demonstrate how MTTR has been shrunk to minutes or hours, by showing how failures can be managed with the new production telemetry and adaptive architecture. An MTTR an order of magnitude faster than deployment lead times will show stakeholders what a team can accomplish with minimal robustness practices.

Each robustness practice subsequently agreed to be risk management theatre should be incrementally replaced with the appropriate mix of Continuous Delivery and operability practices. End-To-End Testing should be superseded by a multi-faceted testing portfolio, in order to turn the resident testing strategy from a Test Ice Cream Cone into a Test Pyramid. This will reduce test execution times and maintenance costs, while simultaneously improving defect discovery rates:

Practice Quantity Frequency Duration Environment
Unit Testing 100 to 1000+ Per build < 30s total Local and Build
Acceptance Testing 10 to 100+ Per build < 10m total Local and Build
Exploratory Testing 10 to 100+ Per build Timebox Local and 3rd Party
Contract Testing ~20 Per 3rd party deploy < 1m 3rd Party
Smoke Testing ~5 Per deploy < 5m All
Monitoring 10 to 100+ Always < 10s All
Anomaly detection 10 to 100+ < 1m < 10s All
Adaptive architecture N/A Always N/A All

Change Advisory Boards and Change Freezes should end in favour of incremental deployments and incremental launches. Blue Green Deployments and Canary Deployments gradually direct users to a newly deployed service version, and users can be redirected to the old version on service failure. Dark Launching controls feature rollouts based on user demographics, and services can be operated in a degraded state on feature failure. Lightweight change management conversations should be reserved for unavoidably large releases, or turbulent market conditions.


Optimising For Robustness is an antiquated, flawed approach to IT reliability that results in long-term Discontinuous Delivery and an operational brittleness that begets failure. As John Allspaw has stated, reliability is “the presence of adaptive capacity, not the absence of failures“. Robustness is of value, but it must be rejected as an outcome if an organisation wants to innovate in changing markets.

Optimising For Resilience is a superior reliability strategy that enables an organisation to gracefully extend to limit the impact of failures, and position itself for sustained adaptability. It is a paradigm shift, in which people need to accept the inherent complexity within their IT services and the hard truth that failures are inevitable. This is neatly summarised by David Woods’ assertion that “graceful extensibility trades off with robust optimality“. An organisation optimised for robustness will reject sources of adaptive capacity such as Circuit Breakers as inefficiencies, but to an organisation optimised for resilience its graceful extensibility is more important than cost efficiencies.

If an organisation has optimised for robustness a Continuous Delivery programme focussed on throughput alone is unlikely to succeed. Resilience As A Continuous Delivery Enabler is a heuristic that advocates resilience as the focus of Continuous Delivery, and using it to bootstrap a Continuous Delivery programme improves production reliability from the outset. Improving the resilience of services by an order of magnitude makes it easier to offer a series of practical alternatives to robustness risk management theatre, and reduce deployment throughput until there is a single value stream that can satisfy business demand 9.

1 Other robustness practices include manual regression testing, segregation of duties, artificial deployment limits, and uptime incentives

2 The Principles of Product Development Flow by Don Reinertsen describes in detail how large batch sizes increase risk

3 The DevOps Handbook by Patrick Debois et al defines telemetry as a logical grouping of logging, monitoring, anomaly detection, alerting, and user analytics

4 In ITIL these are termed Normal and Emergency Changes

5 The Anxiety Of Learning by Edgar Schein describes how people resist change due to learning and survival anxieties

6 How Complex Systems Fail by Richard Cook explains why hindsight bias is such an obstacle to understanding failures, and why root causes do not exist

7 Measuring Continuous Delivery by the author details how to measure the stability and throughput of IT delivery

8 Chaos Engineering should be restricted to test environments in an unsafe-to-fail culture

9 In ITIL these are termed Standard Changes


This series is indebted to John Allspaw and Dave Snowden for their respective work on Resilience Engineering and Cynefin.

Thanks to Beccy Stafford, Charles Kubicek, Chris O’Dell, Edd Grant, Daniel Mitchell, Martin Jackson, and Thierry de Pauw for their feedback on this series.

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