Pivotal Partnership Integration

Felipe Martins
6 min readJan 10, 2024


How I quickly got onboarded onto a pivotal project and led the team to make a crucial architectural decision, enabling its delivery in half of the initial estimated time by leveraging the existing CQS design and correctly applying simple Domain-Driven Design and Hexagonal Architecture principles.


Integrate the company’s financing product as a payment option within e-commerce checkouts through a partnership with a well-established brand that already holds a widespread presence across numerous online stores.


The project held immense pivotal and strategic value, with expectations set remarkably high.

Given its extensive presence and renowned brand in the e-commerce market, the partnership not only promised immediate access to a vast customer base but also aimed to associate the company’s maturing financing product with a trusted brand. A failure would have been catastrophic as such an opportunity with a major partner was a once-in-a-lifetime chance for a startup.

The project’s execution fell under the scope of the “e-commerce integration” department, then composed of two product teams with around 8 engineers in total. These teams had recently encountered delivery delays and inconsistencies, making the successful accomplishment of this partnership project a crucial opportunity to rebuild trust.

And this is where I stepped in.

Joining as a Senior Software Engineer in one of those two teams just weeks before the much-anticipated kickoff, I found a draft solution already on the table.

Technical Context

To bring this partnership to life, we needed to create a public HTTP API that complied with the specifications our new partner has handed over to us. It looked like:

The entire specification included around 10 REST-like endpoints with request and response bodies clearly defined. Additionally, there were response time limits. Pretty straightforward, right?

The company’s existing architecture followed a microservices-like approach, using both asynchronous and synchronous communication methods. While most services adhered decently to bounded contexts, a few technical concerns immediately caught my attention, but that is another discussion not relevant here… let’s get back to the project.

As mentioned earlier, there was already a preliminary solution in place which entailed the creation of a new shiny microservice with the purpose of housing partnership mapping data and redirecting calls to the involved services. Essentially, the solution was an anti-corruption layer (ACL) as a microservice between the partner client and our internal services.

Another justification for creating this new service was scalability. The argument presented was that this new service could supposedly scale independently based on the partner’s demand.

My Contribution

After familiarizing myself with the project’s context, understanding the related microservice’s domain and delving into their relevant use cases, getting to know my teammates, and absorbing the technical details crucial for project success, I began questioning and challenging the new microservice. It became evident to me that implementing it posed significant risks.

Upon scrutinizing the endpoints demanded by the partner, I noticed an important detail: all use cases behind each required endpoint were already implemented in one existing service. This service held many responsibilities, being one of them the direct integration with common e-commerce checkout solutions, such as Magento. There was only one use case previously unnecessary to the directly integrated e-commerce platforms but required for this project. Since its logic was also closely related to e-commerce integration, it would fit well in this same service.

Within my second week at the company, I presented my takes to the team:

  1. Creating a new service for this project seemed unnecessary as there wasn’t a meaningful bounded context justifying such segregated codebase and deployment isolation.
    The existing service responsible for e-commerce checkout integrations could handle everything by simply providing the same use cases via a new port and authentication to accommodate the new client type.
    Leveraging Command Query Separation (CQS) already present in the service design would make implementing a new port almost trivial.
  2. Scalability wouldn’t be resolved solely by creating a new service. The existing service would remain the bottleneck regardless of a new and faster service. Moreover, the new service would likely compromise response time and reliability by introducing another potential failure point, hurting our SLA agreement.
    Furthermore, the planned close collaboration with our partner on the activation of new e-commerce integrations would mitigate the urgency for premature optimization.
  3. The high complexity associated with setting up the new service would heavily drain team resources without commensurate future benefits.
    Additionally, by simply coding into an already running service, the team would focus on smaller releases, allowing shorter feedback cycles and demonstrating progress iteratively.

Following discussions, a consensus was reached and documented. With this simpler solution, the implementation scope was streamlined from a new microservice to a collection of controllers contained in a designated module for this new client type, alongside a table to map inner-vs-outer data and other minor changes.


We surpassed the original tough 4-month estimation by delivering the first store integration within a remarkable 2 months. What initially was apprehension of failure turned into an impressive outcome that resonated throughout upper management and investors. This success affirmed our identity as a startup capable of timely delivering a product meeting the expectations of a major market player.

During the subsequent quarterly meetup, our team received immense recognition for our work. We transitioned from being known for delays to celebrating how our achievement could pivot the product and company.


After reading this story, you might think: “Yeah, that was the obvious solution… not impressed”. It was indeed obvious, but not so much for those immersed in context and facing problems in the service we ended up changing.

My past experience with microservices combined with relevant technical knowledge and argumentation skills has proven key to guiding the team to an architectural decision that would really help us instead of causing future frustration.

A second and even more important learning emerged almost two years later. My contribution could only hold significant weight because of:

  1. My teammates’ openness to listening to a fresh newcomer with far less overall context than they possessed.
  2. Management full trust and support.

I am immensely grateful to all my teammates during that period. Their openness and support enabled me in ways I couldn’t fully comprehend at the time.

Moving forward, I gotta watch myself to never push others back.


The next statements are probably irrelevant to most of the audience, but this is still a blog :)

I had many personal taken from this project since it is the work from my recent career path I am most proud of.

I do believe I nailed this one. While I still gotta much to improve on my argumentation skills, I naturally had the courage to challenge a solution that I knew would burden the team with unnecessary stress and useless work, ultimately escalating costs for the company. Standing up allowed us to collectively deliver a successful outcome with considerably less effort.

Moreover, this project marked my realization that my enthusiasm for microservices isn’t an all obsession. Prior to this project, I had primarily operated in environments where careful extracting services from monoliths brought or could bring substantial benefits. However, here, I proved to myself the importance of striking a balance between the advantages and disadvantages of any decision.

This project also presented to me as the first clear opportunity to bring technical impact beyond coding. While I did also code, the real impact came from learning, challenging, discussion, assessment, and decision. This milestone is aligned with my career goals.

Originally published at https://blog.fefas.dev.



Felipe Martins

Clean Coder and TDD evangelist delivering software ASAP (as simple as possible)