July 17, 2024
Linking Modular Structure to Improvement Groups

This text will show the direct hyperlinks between totally different cellular scaling points,
technical structure and groups. At Thoughtworks we work with many massive enterprises
every presenting totally different issues and necessities when scaling their cellular presence.
We determine two widespread issues seen in massive enterprise cellular app improvement:

  1. A gradual lengthening of the time it takes to introduce new options to a
    market app
  2. Inside function disparity arising from an absence of compatibility/reusability
    between in-house
    market apps

This text charts the journey one in every of our purchasers took when attempting to deal with these
points. We inform the story of how their organisation had up to now, gravitated in direction of
appropriate options, however was not capable of see the anticipated advantages as a consequence of a
misunderstanding of how these options had been intrinsically

We develop this statement by recounting how the identical organisation was capable of obtain a
60% discount in common cycle time, an 18 fold enchancment in improvement prices and an
80% discount in crew startup prices by shifting their team topologies to match a
modular structure whereas on the similar time, investing within the developer

Recognising the Indicators

Regardless of the most effective of intentions, software program typically deteriorates over time, each in
high quality and efficiency. Options take longer to get to market, service outages
change into extra extreme and take longer to resolve, with the frequent outcome that these
engaged on the product change into pissed off and disenfranchised. A few of this may be
attributed to code and its upkeep. Nevertheless, inserting the blame solely on code
high quality feels naive for what’s a multifaceted problem. Deterioration tends to develop
over time by a fancy interaction of product selections, Conway’s regulation, technical
debt and stationary structure.

At this level, it appears logical to introduce the organisation this text relies
round. Very a lot a big enterprise, this enterprise had been experiencing a gradual
lengthening of the time it took to introduce new options
into their retail
cellular software.

As a starter, the organisation had accurately attributed the friction they had been
experiencing to elevated complexity as their app grew- their current improvement
crew struggled so as to add options that remained coherent and per the
current performance. Their preliminary response to this had been to ‘simply add extra
builders’; and this did work to a degree for them. Nevertheless, ultimately it turned
obvious that including extra individuals comes on the expense of extra strained communication
as their technical leaders began to really feel the elevated coordination overhead.
Therefore the ‘two
rule promoted at Amazon: any crew must be sufficiently small to be fed by two
pizzas. The speculation goes that by limiting how huge a crew can change into, you keep away from the
state of affairs the place communication administration takes extra time than precise worth creation.
That is sound principle and has served Amazon effectively. Nevertheless, when contemplating an
current crew that has merely grown too huge, there’s a tendency in direction of ‘cargo
culting’ Amazon’s instance to try to ease that burden…

Limiting Cognitive Load

Certainly, the organisation was no exception to this rule: Their as soon as small monolith had
change into more and more profitable however was additionally unable to duplicate the required fee of
success because it grew in options, duties and crew members. With looming
function supply deadlines and the prospect of a number of model markets on the
horizon, they responded by splitting their current groups into a number of smaller,
linked sub-squads – every crew remoted, managing a person market (regardless of
related buyer journeys).

This in truth, made issues worse for them, because it shifted the communication tax from
their tech management to the precise crew itself, whereas easing none of their
increasing contextual load. Realizing that communication and coordination was sapping
an rising period of time from these tasked with precise worth creation, our
preliminary suggestion concerned the concept of ‘cognitive
outlined by Skelton & Pais (2019). This entails the
separation of groups throughout singular advanced or difficult domains. These seams
inside software program can be utilized to formulate the aforementioned ‘two pizza sized groups’
round. The result’s a lot much less overhead for every crew: Motivation rises, the
mission assertion is clearer, whereas communication and context switching are shrunk
right down to a single shared focus. This was in principle an awesome resolution to our consumer’s
drawback, however can really be deceptive when thought of in isolation. The advantages
from cognitive load limitation can solely actually be realised if an software’s area
boundaries are actually effectively outlined and constantly revered contained in the code.

Area Pushed Self-discipline

Design (DDD) is beneficial for organising advanced logic into manageable teams
and defining a typical language or mannequin for every. Nevertheless, breaking up an
software into domains is simply a part of an ongoing course of. Maintaining tight management
of the
bounded context is as necessary as defining the domains themselves.
Inspecting our consumer’s software’s code we encountered the widespread entice of a transparent
preliminary funding defining and organising area duties accurately, solely
to have began to erode that self-discipline because the app grew. Anecdotal proof from
stakeholders prompt that perpetually busy groups taking shortcuts pushed by
pressing product
necessities had change into the norm
for the crew. This in flip had contributed
to a progressive slowing of worth supply as a result of accumulation of technical
debt. This was highlighted additional nonetheless by a measurable downtrend within the
software’s Four
Key Metrics
because it turned tougher to launch code and tougher to debug

Additional warning indicators of a poorly managed bounded context had been found by
widespread code evaluation instruments. We discovered a codebase that had grown to change into tightly
coupled and missing in cohesion. Extremely
code is tough to vary with out affecting different elements of your system.
Code with low cohesion has many duties and issues that don’t match inside
its remit, making it obscure its objective. Each these points had been
exacerbated over time because the complexity of every area inside our consumer’s app had
grown. Different indications got here with reference once more to cognitive load. Unclear
boundaries or dependencies between domains within the software meant that when a
change was made to at least one, it will probably involuntarily have an effect on others. We observed that
due to this, improvement groups wanted data of a number of domains to resolve
something that may break, rising cognitive load. For the organisation,
implementing rigorous management of every domain-bounded context was a progressive step
ahead in guaranteeing data and duty lay in the identical place. This
resulted in a limitation of the ‘blast radius’ of any adjustments, each within the quantity of
work and data required. As well as, bringing in tighter controls within the
accruing and addressing of technical debt ensured that any brief time period
‘domain-bleeds’ may very well be rejected or rectified earlier than they might develop

One other metric that was lacking from the organisation’s cellular purposes was optionality
of reuse
. As talked about earlier, there have been a number of current, mature model
market purposes. Characteristic parity throughout these purposes was low and a
willingness to unify right into a single cellular app was tough as a consequence of a want for
particular person market autonomy. Tight coupling throughout the system had decreased the flexibility
to reuse domains elsewhere: Having to transplant most of an current cellular app simply
to reuse one area in one other market introduced with it excessive integration and ongoing
administration prices. Our utilisation of correct domain-bounded context management was a
good first step to modularity by discouraging direct dependencies on different domains.
However as we discovered was not the one motion we wanted to take.

Domains that Transcend Apps

State of affairs 1 – ‘The Tidy Monolith’

When considered as a single software in
isolation, merely splitting the app into
domains, assigning a crew, and managing their coupling (in order to not breach
their bounded contexts) works very effectively. Take the instance of a function request
to a person software:

function request is handed to the app squads that personal the related area. Our
bounded context signifies that the blast radius of our change is contained inside
itself, that means our function might be constructed, examined and even deployed with out
having to
change one other a part of our software. We velocity up our time to market and permit
a number of options to be developed concurrently in isolation. Nice!

Certainly, this labored effectively in a singular market context. Nevertheless as quickly as we
tried to deal with our second scaling problem- market function disparity arising
from an absence of reusability
– we began to run into issues.

State of affairs 2 – ‘The Subsequent Market Alternative’

The subsequent step for the group on its quest for modularity of domains was to
obtain speedy improvement financial savings by transplanting elements of the ‘tidy monolith’
into an current market software. This concerned the creation of a typical
framework (facets of which we contact on later) that allowed
functionalities/domains to be reused in a cellular software outdoors its origin.
To raised illustrate our methodology, the instance beneath reveals two market
purposes, one within the UK, the opposite, a brand new app primarily based out of the US. Our US
primarily based software crew has determined that along with their US particular domains
they wish to make use of each the Loyalty Factors and Checkout domains as
a part of their software and have imported them.

For the organisation, this appeared to imply an order of magnitude improvement
saving for his or her market groups vs their conventional behaviour of rewriting area
performance. Nevertheless, this was not the top of the story- In our haste to maneuver
in direction of modularity, we had didn’t bear in mind the prevailing
communication constructions of the organisation that finally dictated the
precedence of labor. Growing our earlier instance as a way to elucidate: After
utilizing the domains in their very own market the US crew had an concept for a brand new function
in one in every of their imported domains. They don’t personal or have the context of that
area so that they contact the UK software crew and submit a function request. The
UK crew accepts the request and maintains that it feels like “an awesome concept”,
solely they’re at the moment “coping with requests from UK primarily based stakeholders”
so it is unclear when they’ll be capable of get to the work…

We discovered that this battle of curiosity in prioritising area performance
limits the quantity of reuse a client of shared performance might anticipate –
this was evident with market groups changing into pissed off on the lack of progress
from imported domains. We theorized numerous options to the issue: The
consuming crew might maybe fork their very own model of the area and
orchestrate a crew round it. Nevertheless, as we knew already, studying/proudly owning an
complete area so as to add a small quantity of performance is inefficient, and
diverging additionally creates issues for any future sharing of upgrades or function
parity between markets. An alternative choice we appeared into was contributions by way of pull
request. Nevertheless this imposed its personal cognitive load on the contributing crew –
forcing them to work in a second codebase, whereas nonetheless relying on help on
cross crew contributions from the first area crew. For instance, it was
unclear whether or not the area crew would have sufficient time between their very own
market’s function improvement to offer architectural steerage or PR critiques.

State of affairs 3 – ‘Market Agnostic Domains’

Clearly the issue lay with how our groups had been organised. Conway’s
regulation is the statement that an organisation will design its enterprise
methods to reflect its personal communication construction. Our earlier examples
describe a state of affairs whereby performance is, from a technical standpoint
from an
possession standpoint continues to be monolithic:
“Loyalty Factors was created
for the UK software so it belongs to that crew”
. One potential
response to that is described within the Inverse
Conway Maneuver
. This entails altering the construction of improvement groups
in order that they permit the chosen technical structure to emerge.

Within the beneath instance we advance from our earlier state of affairs and make the
structural adjustments to our groups to reflect the modular structure we had
beforehand. Domains are abstracted from a particular cellular app and as an alternative are
autonomous improvement groups themselves. After we did this, we observed
relationships modified between the app groups as they not had a dependency
on performance between markets. Of their place we discovered new relationships
forming that had been higher described by way of client and supplier. Our area
groups offered the performance to their market prospects who in flip consumed
them and fed again new function requests to higher develop the area product.

The principle benefit this restructuring has over our earlier iteration is the
clarification of focus. Earlier we described a battle of curiosity that
occurred when a market made a request to vary a website originating from inside
one other market. Abstracting a website from its market modified the main focus from
constructing any performance solely for the good thing about the market, to a extra
holistic mission of constructing performance that meets the wants of its
customers. Success turned measured each in client uptake and the way it was
acquired by the top person. Any new performance was reviewed solely on the
quantity of worth it dropped at the area and its customers general.

Deal with Developer Expertise to Assist Modularity

Recapping, the organisation now had a topological construction that supported modularity
of elements throughout markets. Autonomous groups had been assigned domains to personal and
develop. Market apps had been simplified to configuration containers. In idea, this
all is smart – we are able to plot how suggestions flows from client to supplier fairly
simply. We are able to additionally make excessive stage utopian assumptions like: “All domains are
independently developed/deployed”
or “Customers
‘simply’ pull in no matter reusable domains they want to type an software”

In follow,
nevertheless, we discovered that these are tough technical issues to resolve. For instance,
do you preserve a stage of UX/model consistency throughout autonomous area groups? How
you allow cellular app improvement when you’re solely chargeable for a part of an
software? How do you permit discoverability of domains? Testability? Compatibility
throughout markets? Fixing these issues is totally doable, however imposes its personal
cognitive load, a duty that in our present construction didn’t have any
proprietor. So we made one!

A Area to Clear up Central Issues

Our new area was categorised as ‘the platform’. The platform was
primarily an all encompassing time period we used to explain tooling and steerage
that enabled our groups to ship independently throughout the chosen structure.
Our new area crew maintains the supplier/client relationship we’ve got seen
already, and is chargeable for enhancing the developer expertise for groups
that construct their apps and domains throughout the platform. We hypothesised {that a}
stronger developer expertise will assist drive adoption of our new structure.

However ‘Developer Expertise’ (DX) is sort of a non-specific time period so we thought it
necessary to outline what was required for our new crew to ship an excellent one. We
granularised the DX area right down to a set of vital capabilities – the primary
being, Environment friendly Bootstrapping.

With any widespread framework there’s an inevitable studying curve. developer
expertise goals to scale back the severity of that curve the place doable. Smart
defaults and starter kits are a non-autocratic manner of lowering the friction felt
when onboarding. Some examples we outlined for our platform area:

We Promise that:

  • It is possible for you to to shortly generate a brand new area
    with all related cellular
    dependencies, widespread UI/UX, Telemetry and CI/CD infrastructure in a single
  • It is possible for you to to construct, check and run your area
    Your area will run the identical manner when bundled into an app because it does

Notice that these guarantees describe components of a self-service expertise inside a
developer productiveness platform. We subsequently noticed an efficient
platform as one which allowed groups that had been centered round end-user
performance to focus on their mission somewhat than preventing their manner
by a seemingly infinite record of unproductive

The second vital functionality we recognized for the platform area was Technical
Structure as a Service
. Within the organisation, architectural capabilities additionally
adopted Conway’s regulation and in consequence the duty for structure
selections was concentrated in a separate silo, disconnected from the groups
needing the steerage. Our autonomous groups, whereas capable of make their very own
selections, tended to want some facet of ‘technical shepherding’ to align on
rules, patterns and organisational governance. After we extrapolated these
necessities into an on demand service we created one thing that appears like:

We Promise that:

  • The perfect follow we offer might be accompanied
    with examples that you could
    use or precise steps you may take
  • we’ll preserve an general
    image of area utilization per app and when wanted,
    orchestrate collaboration throughout verticals
  • The trail to
    manufacturing might be seen and proper
  • We’ll work with you”

Notice that these guarantees describe a servant
management relationship to the groups, recognizing that everybody is
chargeable for the structure. That is in distinction to what some would possibly
describe as command and management architectural governance insurance policies.

One final level on the Platform Area, and one value revisiting from the
earlier instance. In our expertise, a profitable platform crew is one that’s
deeply ingrained with their buyer’s wants. In Toyota lean manufacturing, “Genchi Genbutsu” roughly interprets to “Go
and see for your self”
. The concept being that by visiting the supply of the
drawback and seeing it for your self, solely then can you know the way to repair it. We
realized {that a} crew with the main focus of enhancing developer expertise have to be
capable of empathise with builders that use their product to actually perceive
their wants. After we first created the platform crew, we didn’t give this
precept the main focus it deserved, solely to see our autonomous groups discover their very own
manner. This finally prompted duplication of efforts, incompatibilities and an absence
of perception within the structure that took time to rectify.

The Outcomes

We’ve informed the story about how we modularised a cellular app, however how profitable was it
over time? Acquiring empirical proof might be tough. In our expertise, having
a legacy app and a newly architected app throughout the similar organisation utilizing the identical
domains with supply metrics for each is a state of affairs that doesn’t come round too
typically. Nevertheless fortunately for us on this occasion, the organisation was massive sufficient to
be transitioning one software at a time. For these outcomes, we examine two
functionally related retail apps. One legacy with excessive coupling and low cohesion
albeit with a extremely productive and mature improvement crew (“Legacy monolith”). The
different, the results of the modular refactoring train we described beforehand – a
effectively outlined and managed bounded context however with ‘newer’ particular person area groups
supporting (“Area-bounded Context App”). Cycle time is an efficient measure right here
because it represents the time taken to ‘make’ a change within the code and excludes pushing
an app to the store- A variable size course of that App sort has no bearing on.

Cell App Sort Cycle Time
Legacy Monolith 17 days
Area Bounded Context (Avg) 10.3 days

Even when cycle time was averaged throughout all area groups in our second app we noticed a
important uplift versus the Legacy App with a much less skilled crew.

Our second comparability issues optionality of re-use, or lack thereof. On this
state of affairs we look at the identical two cellular apps within the organisation. Once more, we examine
one requiring current area performance (with no selection however to jot down it
themselves) with our modular app (capable of plug and play an current area). We
ignore the widespread steps on the trail to manufacturing since they don’t have any influence on what
we’re measuring. As an alternative, we deal with the facets throughout the management of the
improvement crew and measure our improvement course of from pre-production ‘product
log off’ to dev-complete for a single improvement pair working with a designer

Integration Sort Avg Improvement Time
Non-modular 90 days
Modular 5 days

The dramatically totally different figures above present the ability of a modular structure in
a setting that has a enterprise want for it.

As an apart, it’s value mentioning that these exterior components we’ve got excluded
also needs to be measured. Optimising your improvement efficiency might reveal different
bottlenecks in your general course of. For instance, if it takes 6 months to create a
launch, and governance takes 1 month to approve, then governance is a relatively
small a part of the method. But when the event timeline might be improved to five
days, and it nonetheless takes 1 month to approve, then compliance
might change into the following bottleneck to optimise.

One different benefit not represented within the outcomes above is the impact a crew
organised round a website has on integration actions. We discovered autonomous
area groups naturally seconding themselves into market software groups in an
try and expedite the exercise. This, we imagine, stems from the shift in focus of
a website squad whereby success of its area product is derived from its adoption.

We found two concentric suggestions loops which influence the speed of adoption. The
outer, an excellent integration expertise from the patron of the area (i.e. the app
container). This can be a developer-centric suggestions loop, measured by how simply the
client might configure and implement the area as a part of their general
brand-specific product providing. The inside, an excellent finish person expertise – how effectively
the general journey (together with the built-in area) is acquired by the patron’s
market buyer. A poor client expertise impacts adoption and finally dangers
insulating the area crew from the precise customers of the potential. We discovered that
area groups which collaborate intently with client groups, and which have direct
entry to the top customers have the quickest suggestions loops and consequently had been the
most profitable.

The ultimate comparability value mentioning is one derived from our Platform area.
Beginning a brand new piece of area performance is a time consuming exercise and provides
to the general improvement value for performance. As talked about earlier, the
platform crew goals to scale back this time by figuring out the ache factors within the course of
and optimising them – enhancing the developer expertise. After we utilized this mannequin
to area groups inside our modular structure we discovered an over 80% discount in
startup prices
per crew. A pair might obtain in a day actions that had
been estimated for the primary week of crew improvement!


By now you need to have fairly a rosy image of the advantages of a modular structure
on cellular. However earlier than taking a sledgehammer to your ailing monolithic app, it is
value allowing for the restrictions of those approaches. Firstly, and certainly most
importantly, an architectural shift corresponding to this takes quite a lot of ongoing time and
. It ought to solely be used to resolve critical current enterprise issues
round velocity to market. Secondly, giving autonomy to area groups might be each a
blessing and a curse. Our platform squad can present widespread implementations within the
type of wise defaults however finally the alternatives are with the groups themselves.
Naturally, coalescing on platform necessities corresponding to widespread UI/UX is within the
curiosity of the area squads in the event that they want to be integrated/accepted right into a market
app. Nevertheless, managing bloat from related inner dependencies or eclectic
is difficult. Ignoring this drawback and permitting the general app to
develop uncontrolled is a recipe for poor efficiency within the fingers of the client.
Once more, we discovered that funding in technical management, together with strong
guardrails and tips helps to mitigate this drawback by offering
structure/design oversight, steerage and above all communication.


To recap, at first of this text we recognized two important supply
issues exhibited in an organisation with a multi app technique. A lengthening of
the time it took to introduce new options into manufacturing
and an rising
disparity between different related in home purposes
. We demonstrated that
the answer to those issues lies not in a single technique round technical
structure, crew construction or technical debt, however in a concurrently evolving
composite of all these facets. We began by demonstrating how evolving crew
constructions to help the specified modular and domain-centric structure improves
cognitive and contextual load, whereas affording groups the autonomy to develop
independently of others. We confirmed how a pure development to this was the
elevation of groups and domains to be agnostic of their originating
software/market, and the way this mitigated the consequences of Conway’s regulation inherent with
an software monolith. We noticed that this transformation allowed a client/supplier
relationship to naturally happen. The ultimate synchronous shift we undertook was the
identification and funding within the ‘platform’ area to resolve central issues
that we noticed as a consequence of decoupling groups and domains.

Placing all these facets collectively, we had been capable of show a 60% discount in
cycle time
averaged throughout all modular domains in a market software. We additionally
noticed an 18 fold enchancment in improvement value when integrating modular
domains to a market app somewhat than writing from scratch. Moreover, the deal with
engineering effectiveness allowed our modular structure to flourish as a result of 80%
in startup prices
for brand spanking new domains and the continuing help the ‘platform crew’
offered. In real-terms for our consumer, these financial savings meant with the ability to capitalise
on market alternatives that had been beforehand thought of far too low in ROI to
justify the hassle – alternatives that for years had been the uncontested domains
of their opponents.

The important thing takeaway is {that a} modular structure intrinsically linked to groups might be
extremely helpful to an organisation underneath the proper circumstances. Whereas the
outcomes from our time with the highlighted organisation had been glorious, they had been
particular to this particular person case. Take time to grasp your individual panorama, look
for the indicators and antipatterns earlier than taking motion. As well as, don’t
underestimate the upfront and ongoing effort it takes to deliver an ecosystem like
that which we’ve got described collectively. An unwell thought of effort will greater than
probably trigger extra issues than it solves. However, by accepting that your state of affairs
might be distinctive in scope and thus resisting the pull of the ‘cargo cult’: Specializing in
empathy, autonomy and contours of communication that allow the structure on the
similar time, then there’s each motive you may replicate the successes we’ve got