In the final semester of my undergraduate program, I secured an internship at Quinbay Technologies. This expanded into a full-time software development engineer role after I graduated in August. In this post, I want to expand on some of the coolest things I worked on in blibli.com, and I’m hoping to showcase my process tackling complex requirements.

The product

Blibli.com is an ecommerce product popular in Indonesia. They are also growing a presence in the hyperlocal scene. Quinbay Technologies is a sister company to blibli.com that handles some of the development efforts.

The technology

Blibli is built on a microservice architecture, with most services hosted on Google Cloud platform, and some on their data center on-premises.

Backend servers are written in Java and RxJava, using Spring Boot, built into a Docker container and deployed using Kubernetes.

The frontend is build using the Vue framework. Various parts of the customer and seller interface are split into microsite repositories, which were built and uploaded into a GCS bucket. They are then deployed via an nginx server.

My contributions

Seller fulfillment center revamp

The seller fulfillment center is a portal for sellers to manage their inventory and orders. The code was quite old and unmaintainable, so when the organization decided to take two months across the board to invest in clearing tech debt, we rewrote the entire fulfillment experience.

This project was handed to me along with a part of the team.

• I worked with the project manager to understand and break down the various seller flows.
• Then I distributed the tasks across my team, considering their bandwidth, availability, and inter-dependencies.
• I worked on preparing and maintaining a framework for extensive documentation to ease communication between the tech leads, frontend developers, and API developers.
• I organized API review sessions that squashed many gaps before development even started.
• Since this project required the creation of one new microservice and a new micro-frontend for the seller experience, I worked with infra teams and the seller experience teams to learn, deploy, and integrate the services through our Nginx gateway.

This project spanned just over three months from planning to kickoff, and it was my first experience leading a team and taking ownership of my decisions.

Customer order cancellation

My first big story in Blibli was to build the option for a customer to cancel their order. Before my work, customers could only request a cancellation via customer service. This was quite a complex task, and it introduced me to the intricacies of system design.

There was a pre-existing cancellation flow for sellers and customer service to cancel orders. With some minor tweaks, it could be adapted for customers. But the main difference in the experience was that customers would expect to cancel entire orders, while sellers and customer service could cancel individual items in an order.

The recommendation I received from my lead was to treat the existing cancellation flow as a black box. The naive solution here would be to invoke the black box in a loop. However, this black box was a slow operation, and invoking it multiple times would lead to a poor user experience.

After brainstorming with my lead, we decided that the simplest solution would be to defer the cancellation request to a background job, enqueueing the cancellation of each item via Kafka. The user would be informed that the cancellation was being processed, and they would receive a notification once it was complete.

Stock reconciliation project

This was an incredibly large project that I played a key role in kickstarting. The warehouse data analysts observed that some items were being undersold, and narrowed the root cause to a disparity in stock numbers reported by the overall inventory system and the warehouse stock management system.

There were many steps taken to identify and mitigate this problem to a manageable level, while identifying the root cause of the disparity. It started with a collaboration across all of the inventory service clients to maintain and pass around a tracking ID during any stock transaction. This helped us identify specific stock journeys.

With that, we were able to analyze the data to uniquely tag each tracking ID and group all transactions based on them. Then, we tried to accumulate the stock changes in each group, which identified several clients as sources for the disparities. Working with these teams to spot and squash the bugs was a task that involved a lot of inter-team communication and timeline alignment.

While I was heavily involved in kickstarting this project, I took a back-step after the low-hanging fruit was addressed. I was still involved with communications and tracking progress as well as repairing the stock issues, for which I established a comprehensive SOP that was used by the team.

Production stability

Over the 3+ years I worked at blibli.com, I worked on plenty of other challenging stories. I participated in war rooms and active standby for major sales events.

I worked on migrating the inventory codebase to Spring Boot and Java 17, involving the migration of XML-defined bean mazes and aspect-oriented programming definitions into fully programmatic declarations. This also involved communication with the performance evaluation team to build a benchmark comparing old to new performance impact. We saw a performance improvement of around 50% and a huge improvement in throughput, which enabled us to scale back the service and cut down considerably on cloud costs.

There was an incredibly complex ingest process that we had to revamp. It was related to generating QR codes in bulk for sellers to display on their products in a store. This was a refreshing and challenging task, due to the constraints we had. The entire flow was orchestrated with Kafka as its backbone.

I also conducted interviews for a couple of intern cohorts, which was honestly a bit stressful until I got the hang of it.

Conclusion

My time at blibli.com was incredibly enlightening and emboldened my confidence in my knowledge and wisdom. I am ever grateful for the oppotunity to lead and take ownership, to be able to make important decisions knowing that I had support from my seniors and peers, and to be given the space to fail and learn from mistakes. Thanks for everything, folks!