Team Topologies
by Matthew Skelton and Manuel Pais
Pitch
Effective software teams are essential for any organization to deliver value continuously and sustainably.
But how do you build the best team organization for your specific goals, culture, and needs?
Team Topologies is a practical, step-by-step, adaptive model for organizational design and team interaction based on four fundamental team types and three team interaction patterns.
It is a model that treats teams as the fundamental means of delivery, where team structures and communication pathways are able to evolve with technological and organizational maturity.
In Team Topologies, IT consultants Matthew Skelton and Manuel Pais share secrets of successful team patterns and interactions to help readers choose and evolve the right team patterns for their organization, making sure to keep the software healthy and optimize value streams.
Team Topologies is a major step forward in organizational design for software, presenting a well-defined way for teams to interact and interrelate that helps make the resulting software architecture clearer and more sustainable, turning inter-team problems into valuable signals for the self-steering organization.
Infographic
Preface
A functional book
Part I - explores Conway’s law
The way organizational interrelationships constrain the design of systems we build
And how we can use this tendency to our advantage
Part II - set of static team patterns
Have been proven in the industry and the implications of choosing one pattern over another
with Conway’s law and organizational context in mind
Part III - ways to evolve the organization design
To provide powerful capabilities for innovation and rapid delivery i
How to use the Team Topologies approach to create a sensing organization that responds to the market and user demands,
And accounts for the implications this has for hiring and skills
Part 1 - Team As The Means of Delivery
The Problem with Org Charts
Must shift our thinking from treating teams as collections of interchangeable individuals that will succeed as long as they follow the “right” process and use the “right” tools
TO treating people and technology as a single human/computer carbon/silicon sociotechnical ecosystem
We need to ensure that teams are intrinsically motivated and are given a real chance of doing their best work within such a system
Team Topologies focuses on
how to set up dynamic team structures
interaction modes that can help teams adapt quickly to new conditions
Org chart is always out os sync with reality
By empowering teams, and treating them as fundamental building blocks
Individuals inside those teams move closer together to act as a team rather than just a group of people
Explicitly agree on interaction modes with other teams
Expectations on behaviors become clearer and inter-team trust grows
Cognitive Load and Bottlenecks
Conway's law
An organization that is arranged in functional silos
Where teams specialize in a particular function, such as QA, DBA, or security
Is unlikely to ever produce software systems that are well-architected for end-to-end flow
The Reverse Conway Maneuver
Accelerate: The Science of Dev Ops
"Our research lends support to what is sometimes called the “inverse Conway maneuver,” which states that organizations should evolve their team and organizational structure to achieve the desired architecture. The goal is for your architecture to support the ability of teams to get their work done—from design through to deployment—without requiring high-bandwidth communication between teams."
“Team assignments are the first draft of the architecture." - Michael Nygard
The fundamental means of delivery is the team
The system architecture needs to
Enable
Encourage fast flow within each team
In practice, this means that we can follow proven software-architecture good practices:
Loose coupling—components do not hold strong dependencies on other components
High cohesion—components have clearly bounded responsibilities, and their internal elements are strongly related
Clear and appropriate version compatibility
Clear and appropriate cross-team testing
Organization Design Requires Technical Expertise
“if we have managers deciding . . . which services will be built, by which teams, we implicitly have managers deciding on the system architecture.” - Ruth Malan
How much awareness does the HR department have about software systems?
Does the group of department leaders deciding how to allocate budget across teams know of the likely effects of their choices on the viability of the software architecture?
Restrict Unnecessary Communication
Not all communication and collaboration is good
We need focused communication between specific teams
2 rules
The organization’s design limits the number of possible solutions for a given system’s architecture
The speed of software delivery is strongly affected by how many team dependencies the organization design instills
Fast flow requires restricting communication between teams
Team collaboration is important for gray areas of development
Where discovery and expertise is needed to make progress
“Disbanding high-performing teams is worse than vandalism: it is corporate psychopathy." — Allan Kelly, Project Myopia
Team first-thinking
Research by Google on their own teams
Who is on the team matters less than the team dynamics
When it comes to measuring performance, teams matter more than individuals
Use Small, Long-Lived Teams as the Standard
“team” = stable grouping of five to nine people who work toward a shared goal as a unit
An organization should never assign work to individuals; only to teams
Allowing teams to grow beyond the magic seven-to-nine size imperils the viability of the software being built by that team (Dunbar’s number)
Trust will begin to break down
Unsuitable decisions might ensue
Organizations need to maximize trust between people on a team
That means limiting the number of team members
Smaller Size Fosters Trust
Anthropological research shows that the type and depth of relationship we can have with people has clear limits :
Around five people—limit of people with whom we can hold close personal relationships and working memory
Around fifteen people—limit of people with whom we can experience deep trust
Around fifty people—limit of people with whom we can have mutual trust
Around 150 people—limit of people whose capabilities we can remember
The Team Owns the Software
With small, long-lived teams in place
We can begin to improve the ownership of software
Team ownership helps to provide the vital “continuity of care”
The danger of allowing multiple teams to change the same system or subsystem
No one owns the changes made or the resulting mess
There should be no shared ownership of components, libraries, or code
Team Members Need a Team-First Mindset
Put the needs of the team above their own
Embrace Diversity in Teams
Find Novel and creative ways
Produce more creative solutions
Reward the Whole Team not individuals
Good Boundaries Minimize Cognitive Load
Organizations need to ensure that the cognitive load on a team is not too high
Restrict Team Responsibilities to Match Team Cognitive Load
Cognitive load
Characterized in 1988
By psychologist John Sweller
“the total amount of mental effort being used in the working memory.”
3 types of cognitive load
Intrinsic —relates to aspects of the task fundamental to the problem space
What is the structure of a Java class?
How do I create a new method?
Extraneous —relates to the environment in which the task is being done
How do I deploy this component again?
How do I configure this service?
Germane —relates to aspects of the task that need special attention for learning or high performance
How should this service interact with the ABC service?
Measure the Cognitive Load Using Relative Domain Complexity
Ask the team :
“Do you feel like you’re effective and able to respond in a timely fashion to the work you are asked to do?”
Trying to determine the cognitive load of software using simple measures such as lines of code, number of modules, classes, or methods is misguided
When measuring cognitive load
what we really care about = domain complexity
how complex is the problem that we’re trying to solve with software?
A domain = a more largely applicable concept than software size
3 heuristics
Assign each domain to a single team
Instead of splitting responsibilities of a single domain to multiple teams
Split the domain into subdomains
Then assign each new subdomain to a single team
A single team should be able to accommodate two to three “simple” domains”
A team responsible for a complex domain should not have any more domains assigned to them—not even a simple one
Design “Team APIs” and Facilitate Team Interactions
Team API = an API surrounding each team
It includes :
Code: runtime endpoints, libraries, clients, UI, etc. produced by the team
Versioning: how the team communicates changes to its code and services
Wiki and documentation: especially how-to guides for the software owned by the team
Practices and principles: the team’s preferred ways of working
Communication: the team’s approach to remote communication tools, such as chat tools and video conferencing
Work information: what the team is working on now, what’s coming next, and overall priorities in the short to medium term
Other: anything else that other teams need to use to interact with the team
Team API should consider usability by other teams
Part 2 - Team Topologies that Work for Flow
Stream-Aligned teams
“stream” : the continuous flow of work aligned to a business domain or organizational capability
Requires clarity of purpose and responsibility
Team aligned to a single, valuable stream of work
Might be
A single product or service
A single set of features
A single user journey
or a single user persona
Work on the full spectrum of delivery
Primary team type in an organization
Capabilities
Application security
Commercial and operational viability analysis
Design and architecture
Development and coding
Infrastructure and operability
Metrics and monitoring
Product management and ownership
Testing and quality assurance User experience (UX)
critical not to assume each capability maps to an individual role in the team
Be able, as a team, to
understand and act upon the above capabilities
Have a mix of generalists and a few specialists
Expected Behaviors
Aims to produce a steady flow of feature delivery
Correct based on feedback from the latest changes
Uses an experimental approach to product evolution
Expecting to constantly learn and adapt
Team has minimal (ideally zero) hand-offs of work to other teams
Must have time and space to address code quality changes (sometimes called “tech debt”) to ensure that changing the code remains safe and easy to do.
Proactively and regularly reaches out to the supporting fundamental-topologies teams (complicated subsystem, enabling, and platform)
Feel they have achieved or are in the path to achieving “autonomy, mastery, and purpose,” the three key components of engaged knowledge workers, according to Daniel Pink
Enabling Teams
In Accelerate High-performing teams are continuously improving their capabilities in order to stay ahead
But how can a stream-aligned team with end-to-end ownership find the space for researching, reading about, learning, and practicing new skills?”
Enabling team is composed of specialists in a given technical (or product) domain
They help bridge this capability gap
Have a strongly collaborative nature
Avoid becoming “ivory towers” of knowledge
Increase the autonomy of stream-aligned teams by growing their capabilities
With a focus on their problems first
Not the solutions per se
Should not be a permanent dependency
Expected Behaviors
Seeks to understand the needs of stream-aligned teams
Establishing regular checkpoints
Jointly agreeing when more collaboration is needed
Stays ahead of the curve in keeping abreast of new approaches, tooling, and practices in their area of expertise
Act as a proxy for external (or internal) services that are currently too difficult for stream-aligned teams to use directly
Promotes learning not only inside the enabling team but across stream-aligned teams
Acting as a curator that facilitates appropriate knowledge sharing inside the organization
Complicated-Subsystem Teams
Responsible for building and maintaining
a part of the system that depends heavily on specialist knowledge
GOAL of this team :
Reduce the cognitive load of stream-aligned teams
working on systems that include or use the complicated subsystem
Examples :
Video processing codec
Mathematical model
Real-time trade reconciliation algorithm
Transaction reporting system for financial services
Face-recognition engine
Created only when a subsystem needs mostly specialized knowledge
Expected Behaviors
Mindful of the current stage of development of the subsystem / acts accordingly
High collaboration with stream-aligned teams during early exploration and development phases
Reduced interaction and focus on the subsystem interface and feature evolution and usage during later stages
Delivery speed and quality for the subsystem is clearly higher than if/when the subsystem was being developed by a stream-aligned team
Prioritizes and delivers upcoming work
Respecting the needs of the stream-aligned teams that use the complicated subsystem
Platform Teams
Purpose : enable stream-aligned teams to deliver work with substantial autonomy
Provides internal services to reduce the cognitive load that would be required from stream-aligned teams to develop these underlying services
Treat the services they offer as products
reliable
usable
fit for purpose
A thick platform might consist of the combination of several inner platform teams
Providing a myriad of services
A thin platform
could simply be a layer on top of a vendor-provided solution
Examples :
From provisioning a new server instance
To providing tools for access management and security enforcement
Expected Behaviors
Uses strong collaboration with stream-aligned teams to understand their needs
Relies on fast prototyping techniques
Involves stream-aligned team members for fast feedback
Has a strong focus on
Usability and reliability for their services
Treating the platform as a product
Regularly assesses if the services are still fit for purpose and usable
Leads by example
Using the services they provide internally (when applicable)
Partnering with stream-aligned teams and enabling teams
Consuming lower level platforms (owned by other platform teams) whenever possible
Understands that adoption of internal new services, like new technologies, is not immediate, but instead evolves along an adoption curve
A Good Platform Is “Just Big Enough”
A good platform provides
standards
templates
APIs
well-proven best practices for Dev teams to use to innovate rapidly and effectively
Thinnest Viable Platform
A list on a wiki page of underlying components or services used by consuming software
Convert Common Team Types to the Fundamental Team Topologies
Infrastructure Teams to Platform Teams
Platform is managed as a product using proven software development techniques
May be quite unfamiliar to infrastructure people
Component teams to Platform or Other Team Types
DBA teams -> enabling teams
Focus on spreading awareness of DB Perf, monitoring, ...
Tooling Teams to Enabling Teams or Part of the Platform
Converting Architecture and Architects
Most effective pattern : a part-time enabling team
Emphasizes that many decisions should be taken by implementing teams rather than left to the architecture team
Software Boundaries or “Fracture Planes
Look for similar fracture planes in software
To find the natural split points that lead to software boundaries
Fracture Plane: Business Domain Bounded Context
A bounded context :
A unit for partitioning a larger domain (or system) model into smaller parts
Each of which represents an internally consistent business domain area
Identifying bounded contexts :
Requires a fair amount of business knowledge and technical expertise
Aligns technology with business
Reduces mismatches in terminology and “lost in translation” issues, improving the flow of changes and reducing rework
Fracture Plane: Regulatory Compliance
Fracture Plane: Change Cadence
With a monolith, every piece moves at the speed of the slowest part
Splitting off the parts of the system that typically change at different speeds allows them to change more quickly
Fracture Plane: Team Location
Working across different time zones aggravates communication delays and introduces bottlenecks
Fracture Plane: Risk
Splitting off subsystems with clearly different risk profiles allows mapping the technology changes to business appetite or regulatory
Fracture Plane: Performance Isolation
In particular types of systems, differentiating levels of performance might be beneficial
Splitting off such a subsystem based on particular performance demands helps to ensure
it can scale autonomously
increasing performance and reducing cost
Fracture Plane: Technology
Fracture Plane: User Personas
Part 3 - Evolving Team Interactions for Innovation and Rapid Delivery
Team Interaction Modes
Team topologies used should adapt and evolve to meet emerging challenges
3 core team interaction modes that simplify and clarify the essential interactions needed between teams building software systems
Collaboration : two teams work together on a shared goal, particularly during discovery of new technology or approaches.
The overhead is valuable due to the rapid pace of learning
X-as-a-Service : one team consumes something provided by another team (such as an API, a tool, or a full software product).
Collaboration is minimal
Facilitating : one team (usually an enabling team) facilitates another team in learning or adopting a new approach.
Well-Defined Interactions Are Key to Effective Teams
Teams should ask:
What kind of interaction should we have with this other team?
Should we be collaborating closely with the other team?
Should we be expecting or providing a service?
Or should we be expecting or providing facilitation?
The team on the right is providing something “as a service” to the team on the left (perhaps an API, some developer tooling, or even an entire platform).
Choose suitable Team interaction modes
Collaboration
X-as-a-Service
Facilitating
Stream-aligned
Typical
Typical
Occasional
Enabling
Occasional
Typical
Complicated-subsystem
Occasional
Typical
Platform
Occasional
Typical
Constant Evolution of Team Topologies
Triggers for Evolution of Team Topologies
it's often difficult to have the required organizational self-awareness to detect when it’s time to evolve the team structure
Trigger: Software Has Grown Too Large for One Team
Symptoms :
A startup company grows beyond fifteen people (Dunbar’s number)
Other teams spend lots of time waiting on a single team
Changes to certain components or workflows in the system routinely get assigned to the same people, even when they’re already busy or away
Team members complain about lack of system documentation
Trigger: Delivery Cadence Is Becoming Slower
Team members qualitatively feel it takes longer to release changes
Team velocity or throughput metrics show a clear downward variation compared to one year ago
Team members complain that the delivery process used to be simpler, with fewer steps.
Work in progress keeps increasing
Conclusion
Team Topologies alone will not produce an effective software-delivery and operations organization. Beyond the structures and dynamics suggested in this book, important additional ingredients of success include :
A healthy organizational culture :
an environment that supports the professional development of individuals and teams
which people feel empowered
Safe to speak
The organization expects to learn continuously
Good engineering practices :
Test-first design and development of all aspects of the systems
a focus on continuous delivery and operability practices
pairing and mobbing for code review
avoiding the search for a single “root cause” for incidents
designing for testability, and so on
Healthy funding and financial practices :
Avoiding the pernicious effects of a CapEx/OpEx
Avoiding project-driven deadlines and large-batch budgeting wherever possible
Allocating training budgets to teams or groups rather than individuals
Clarity of business vision :
Executive or leadership provides a clear vision and direction
with horizons at human-relevant timescales
clear reasoning behind the priorities
So people in the organization can understand how and why these were chosen.
How to get started ?
Start with the Team
What does the team need in order to :
Act and operate as an effective team?
Own part of the software effectively?
Reduce unnecessary cognitive load?
Consume and provide software and information to other teams?
Identify Suitable Streams of Change
Identify a Thinnest Viable Platform (TVP)
Identify the services needed to support a reliable, swift flow of change in those streams
Identify Capability Gaps in Team Coaching, Mentoring, Service Management, and Documentation
Ensure that your teams are populated not just with technologists
BUT also with people who have other skills
Examples : Team coaching, Mentoring, Well written documentation
Share and Practice Different Interaction Modes and Explain Principles behind New Ways of Working
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