@boltaevt
3 min readJan 27, 2024

Mastering Endpoint Proxying in Microservice Ecosystems

The architecture of microservices stands as a beacon of modular design, allowing teams to build, deploy, and scale their systems independently. However, this architectural style isn’t without its complexities, especially when it comes to the interaction between different services — a scenario where endpoint proxying becomes a necessity.

The Scenario: Proxying Between Services

Consider a microservice ecosystem where Service A acts as the facade, dealing with various client-side applications, while Service B is the workhorse, handling data processing tasks like sorting, filtering, and generating files. The challenge arises when Service A needs to proxy requests to Service B, ensuring a seamless client experience.

Challenges Faced

The journey through endpoint proxying is often fraught with challenges that demand both technical acumen and collaborative effort. I encountered my first obstacle when I realized that Service A had to replicate the endpoint functionalities of Service B. Initially, I emulated the response structure of Service B by closely examining its responses and codebase, ensuring that the proxy endpoint in Service A mimicked it precisely.

Dealing with Query String Parsing

The frontend’s utilization of the `qs` library for query string parsing presented an unexpected challenge. The library processed request parameters in a manner that Service A could not interpret correctly. This issue was particularly vexing as it threatened the integrity of the proxying function. Through collaborative debugging sessions and code reviews with the frontend team, we were able to resolve the parsing discrepancies.

Handling File Downloads

The task of proxying a GET method for Excel file downloads presented a unique conundrum. My initial implementation of simply returning a byte array, though theoretically sound, was practically insufficient. It lacked the nuance required for proper file handling in HTTP responses.

Guided by insights from Service B’s implementation and constructive feedback from my peers, I recognized the need for a more sophisticated approach. This realization led me to construct a `ResponseEntity<byte[]>` in Service A, complete with the necessary HTTP headers to instruct the client on how to handle the file download.

Despite this improved approach, integrating Service B’s `ResponseEntity<byte[]>` at Service A proved challenging. Customizing Feign decoders to manage the content type was a step in the right direction, but it wasn’t the panacea I had hoped for. The integration required a deeper understanding and further refinements that I have earmarked for future development cycles.

A Revelation: Aligning with Frontend Expectations

In an enlightening exchange with the frontend team, I learned that the expected file handling was not through the ResponseEntity mechanism but rather within the body of a custom class, conforming to the frontend’s existing data models and naming conventions.

Key Takeaways and Best Practices

This experience has distilled several key lessons and best practices:

Understand Before You Implement: Before proxying an endpoint, it’s imperative to understand how the existing service fulfills its responsibilities. Analyze how it processes requests, generates responses, and handles files.

Clarify Expectations Early: Engage with stakeholders, especially those on the frontend, to understand their expectations. Knowing the exact client-side requirements can save time and prevent rework.

Collaborate and Communicate: When faced with technical challenges, foster a culture of open communication and collaboration. Solutions often emerge from collective brainstorming and knowledge sharing.

Iterate and Refine: Be prepared to iterate on your solutions. As new information and feedback become available, refining your approach is not only necessary but also conducive to better outcomes.

Documentation and Knowledge Transfer: Ensure that the nuances of your implementation are well-documented. This practice aids in knowledge transfer and helps maintain the system’s integrity over time.

The journey through endpoint proxying is emblematic of the microservice paradigm’s challenges and triumphs. It tests our technical skills, our ability to work collaboratively, and our commitment to continuous improvement. Embrace these challenges with a spirit of inquiry and collaboration, and let each hurdle be a stepping stone towards mastery. Remember, it’s not just about building software; it’s about crafting an experience that delights and delivers.

@boltaevt

Ex-corporate lawyer turned Java developer. Passionate about exploring the vast sea of technologies. LinkedIn: https://www.linkedin.com/in/boltaevt/.