Linking Modular Structure to Improvement Groups

This text will exhibit the direct hyperlinks between completely different cellular scaling points,
technical structure and groups. At Thoughtworks we work with many giant enterprises
every presenting completely different issues and necessities when scaling their cellular presence.
We establish two widespread issues seen in giant 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 a scarcity of compatibility/reusability
    between in-house
    market apps

This text charts the journey certainly one of our shoppers took when making an attempt to handle these
points. We inform the story of how their organisation had prior to now, gravitated in the direction of
right options, however was not in a position to see the anticipated advantages on account of a
misunderstanding of how these options have been intrinsically

We develop this remark by recounting how the identical organisation was in a position to 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 crew topologies to match a
modular structure whereas on the similar time, investing within the developer

Recognising the Indicators

Regardless of the perfect of intentions, software program usually 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, putting the blame solely on code
high quality feels naive for what’s a multifaceted concern. Deterioration tends to develop
over time via a posh interaction of product selections, Conway’s regulation, technical
debt and stationary structure.

At this level, it appears logical to introduce the organisation this text is predicated
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 utility.

As a starter, the organisation had appropriately attributed the friction they have been
experiencing to elevated complexity as their app grew- their present improvement
crew struggled so as to add options that remained coherent and in step with the
present performance. Their preliminary response to this had been to ‘simply add extra
builders’; and this did work to some extent for them. Nevertheless, ultimately it grew to become
obvious that including extra folks comes on the expense of extra strained communication
as their technical leaders began to really feel the elevated coordination overhead.
Therefore the ‘two
pizza’ rule promoted at Amazon: any crew ought to be sufficiently small to be fed by two
pizzas. The speculation goes that by limiting how massive 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 idea and has served Amazon properly. Nevertheless, when contemplating an
present crew that has merely grown too massive, there’s a tendency in the 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 price of
success because it grew in options, tasks 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 present groups into a number of smaller,
related sub-squads – every crew remoted, managing a person market (regardless of
comparable buyer journeys).

This in reality, 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 growing period of time from these tasked with precise worth creation, our
preliminary suggestion concerned the concept of ‘cognitive
limitation’ outlined by Skelton & Pais (2019). This entails the
separation of groups throughout singular complicated or sophisticated 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
all the way down to a single shared focus. This was in idea an ideal resolution to our shopper’s
drawback, however can truly be deceptive when thought-about in isolation. The advantages
from cognitive load limitation can solely really be realised if an utility’s area
boundaries are really properly outlined and constantly revered contained in the code.

Area Pushed Self-discipline

Design (DDD) is beneficial for organising complicated logic into manageable teams
and defining a typical language or mannequin for every. Nevertheless, breaking up an
utility into domains is barely a part of an ongoing course of. Conserving tight management
of the
bounded context is as vital as defining the domains themselves.
Analyzing our shopper’s utility’s code we encountered the widespread lure of a transparent
preliminary funding defining and organising area tasks appropriately, solely
to have began to erode that self-discipline because the app grew. Anecdotal proof from
stakeholders urged 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
utility’s 4
Key Metrics because it grew to become harder to launch code and tougher to debug

Additional warning indicators of a poorly managed bounded context have been found via
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 components of your system.
Code with low cohesion has many tasks and considerations that don’t match inside
its remit, making it obscure its function. Each these points had been
exacerbated over time because the complexity of every area inside our shopper’s app had
grown. Different indications got here with reference once more to cognitive load. Unclear
boundaries or dependencies between domains within the utility meant that when a
change was made to at least one, it might seemingly 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, growing cognitive load. For the organisation,
implementing rigorous management of every domain-bounded context was a progressive step
ahead in guaranteeing data and accountability 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’ might be rejected or rectified earlier than they may develop

One other metric that was lacking from the organisation’s cellular functions was optionality
of reuse
. As talked about earlier, there have been a number of present, mature model
market functions. Function parity throughout these functions was low and a
willingness to unify right into a single cellular app was tough on account of a need for
particular person market autonomy. Tight coupling throughout the system had diminished the flexibility
to reuse domains elsewhere: Having to transplant most of an present 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 came upon 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 utility 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 properly. Take the instance of a function request
to a person utility:

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

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

State of affairs 2 – ‘The Subsequent Market Alternative’

The following step for the group on its quest for modularity of domains was to
obtain speedy improvement financial savings by transplanting components of the ‘tidy monolith’
into an present market utility. This concerned the creation of a typical
framework (elements of which we contact on later) that allowed
functionalities/domains to be reused in a cellular utility outdoors its origin.
To raised illustrate our methodology, the instance beneath exhibits two market
functions, one within the UK, the opposite, a brand new app based mostly out of the US. Our US
based mostly utility 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 utility 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 tip of the story- In our haste to maneuver
in the direction of modularity, we had did not bear in mind the present
communication constructions of the organisation that in the end dictated the
precedence of labor. Creating our earlier instance as a method to elucidate: After
utilizing the domains in their very own market the US crew had an thought for a brand new function
in certainly one of their imported domains. They don’t personal or have the context of that
area in order that they contact the UK utility crew and submit a function request. The
UK crew accepts the request and maintains that it seems like “an ideal thought”,
solely they’re presently “coping with requests from UK based mostly stakeholders”
so it is unclear when they’ll be capable to get to the work…

We discovered that this battle of curiosity in prioritising area performance
limits the quantity of reuse a shopper of shared performance may anticipate –
this was evident with market groups changing into pissed off on the lack of progress
from imported domains. We theorized quite a lot of options to the issue: The
consuming crew may maybe fork their very own model of the area and
orchestrate a crew round it. Nevertheless, as we knew already, studying/proudly owning an
total 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. Another choice we regarded into was contributions through 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 steering or PR evaluations.

State of affairs 3 – ‘Market Agnostic Domains’

Clearly the issue lay with how our groups have been organised. Conway’s
regulation is the remark that an organisation will design its enterprise
programs to reflect its personal communication construction. Our earlier examples
describe a situation whereby performance is, from a technical standpoint
from an
possession standpoint remains to be monolithic:
“Loyalty Factors was created
for the UK utility 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 situation 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. Once we did this, we observed
relationships modified between the app groups as they now not had a dependency
on performance between markets. Of their place we discovered new relationships
forming that have been higher described when it comes to shopper and supplier. Our area
groups supplied the performance to their market prospects who in flip consumed
them and fed again new function requests to higher develop the area product.

The primary 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 grew to become measured each in shopper uptake and the way it was
acquired by the tip consumer. Any new performance was reviewed solely on the
quantity of worth it delivered to the area and its customers total.

Deal with Developer Expertise to Help Modularity

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

In observe,
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 if you end up solely liable for a part of an
utility? How do you permit discoverability of domains? Testability? Compatibility
throughout markets? Fixing these issues is solely potential, however imposes its personal
cognitive load, a accountability that in our present construction didn’t have any
proprietor. So we made one!

A Area to Resolve 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 steering
that enabled our groups to ship independently throughout the chosen structure.
Our new area crew maintains the supplier/shopper relationship now we have seen
already, and is liable for bettering 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 kind of a non-specific time period so we thought it
vital to outline what was required for our new crew to ship a superb one. We
granularised the DX area all the way down to a set of needed capabilities – the primary
being, Environment friendly Bootstrapping.

With any widespread framework there may be an inevitable studying curve. A great developer
expertise goals to cut back the severity of that curve the place potential. Wise
defaults and starter kits are a non-autocratic means of decreasing the friction felt
when onboarding. Some examples we outlined for our platform area:

We Promise that:

  • It is possible for you to to rapidly 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, take a look at and run your area
  • Your area will run the identical means when bundled into an app because it does

Notice that these guarantees describe parts of a self-service expertise inside a
developer productiveness platform. We due to this fact noticed an efficient
platform as one which allowed groups that have been targeted round end-user
performance to focus on their mission moderately than combating their means
via a seemingly countless checklist of unproductive

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

We Promise that:

  • The very best observe we offer might be accompanied
    with examples that you could
    use or precise steps you possibly can take
  • we’ll preserve an total
    image of area utilization per app and when wanted,
    orchestrate collaboration throughout verticals
  • The trail to
    manufacturing might be seen and proper
  • We are going to work with you”

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

One final level on the Platform Area, and one price 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 thought being that by visiting the supply of the
drawback and seeing it for your self, solely then can you understand how to repair it. We
realized {that a} crew with the main focus of bettering developer expertise have to be
in a position to empathise with builders that use their product to really perceive
their wants. Once 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
means. This in the end induced duplication of efforts, incompatibilities and a scarcity
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 may 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 situation that doesn’t come round too
usually. Nevertheless fortunately for us on this occasion, the organisation was giant sufficient to
be transitioning one utility at a time. For these outcomes, we evaluate two
functionally comparable 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
properly outlined and managed bounded context however with ‘newer’ particular person area groups
supporting (“Area-bounded Context App”). Cycle time is an effective 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.

Cellular 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
vital uplift versus the Legacy App with a much less skilled crew.

Our second comparability considerations optionality of re-use, or lack thereof. On this
situation we study the identical two cellular apps within the organisation. Once more, we evaluate
one requiring present area performance (with no selection however to jot down it
themselves) with our modular app (in a position to plug and play an present area). We
ignore the widespread steps on the trail to manufacturing since they haven’t any impression on what
we’re measuring. As an alternative, we concentrate on the elements throughout the management of the
improvement crew and measure our improvement course of from pre-production ‘product
log out’ 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 completely different figures above present the facility of a modular structure in
a setting that has a enterprise want for it.

As an apart, it’s price mentioning that these exterior elements now we have excluded
must also be measured. Optimising your improvement efficiency might reveal different
bottlenecks in your total 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 may be improved to five
days, and it nonetheless takes 1 month to approve, then compliance
might change into the subsequent 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 utility groups in an
try to 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 impression the speed of adoption. The
outer, a superb integration expertise from the buyer of the area (i.e. the app
container). It is a developer-centric suggestions loop, measured by how simply the
shopper may configure and implement the area as a part of their total
brand-specific product providing. The internal, a superb finish consumer expertise – how properly
the general journey (together with the built-in area) is acquired by the buyer’s
market buyer. A poor shopper expertise impacts adoption and in the end dangers
insulating the area crew from the precise customers of the aptitude. We discovered that
area groups which collaborate intently with shopper groups, and which have direct
entry to the tip customers have the quickest suggestions loops and consequently have been the
most profitable.

The ultimate comparability price 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 price for performance. As talked about earlier, the
platform crew goals to cut back this time by figuring out the ache factors within the course of
and optimising them – bettering the developer expertise. Once we utilized this mannequin
to area groups inside our modular structure we discovered an over 80% discount in
startup prices
per crew. A pair may obtain in a day actions that had
been estimated for the primary week of crew improvement!


By now it’s best 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
price taking into consideration the constraints of those approaches. Firstly, and certainly most
importantly, an architectural shift resembling this takes loads of ongoing time and
. It ought to solely be used to resolve severe present enterprise issues
round velocity to market. Secondly, giving autonomy to area groups may be each a
blessing and a curse. Our platform squad can present widespread implementations within the
type of smart defaults however in the end the alternatives are with the groups themselves.
Naturally, coalescing on platform necessities resembling 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 comparable inner dependencies or eclectic
is hard. Ignoring this drawback and permitting the general app to
develop uncontrolled is a recipe for poor efficiency within the fingers of the shopper.
Once more, we discovered that funding in technical management, along with sturdy
guardrails and tips helps to mitigate this drawback by offering
structure/design oversight, steering and above all communication.


To recap, at the beginning of this text we recognized two vital 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 growing
disparity between different comparable in home functions
. 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 elements. 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
utility/market, and the way this mitigated the consequences of Conway’s regulation inherent with
an utility monolith. We noticed that this transformation allowed a shopper/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 elements collectively, we have been in a position to exhibit a 60% discount in
cycle time
averaged throughout all modular domains in a market utility. We additionally
noticed an 18 fold enchancment in improvement price when integrating modular
domains to a market app moderately than writing from scratch. Moreover, the concentrate on
engineering effectiveness allowed our modular structure to flourish as a result of 80%
in startup prices
for brand new domains and the continued help the ‘platform crew’
supplied. In real-terms for our shopper, these financial savings meant with the ability to capitalise
on market alternatives that have been beforehand thought-about 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 may be
extremely useful to an organisation below the suitable circumstances. Whereas the
outcomes from our time with the highlighted organisation have been wonderful, they have been
particular to this particular person case. Take time to know your personal 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 carry an ecosystem like
that which now we have described collectively. An unwell thought-about effort will greater than
seemingly 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 features of communication that allow the structure on the
similar time, then there may be each purpose you could possibly replicate the successes now we have

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