Spring Modulith: Lessons Learned from Implementation Challenges

Tim's team transformed their development process by adopting Spring Modulith, learning from mistakes to enhance code quality and efficiency.

### Tim's Insights on Working with Spring Modulith
Tim, an engineering lead at km, shares his excitement about the Spring Modulith project and discusses the mistakes his team made while working with it. He explains the role of the intelligence team in conducting security assessments for km operations, including evaluating the **safety of flights, stations, and hotels for the crew**. Tim emphasizes the importance of assessing global events, like protests, to determine their **impact on km's operations and ensuring the safety of the crew**.

### Automating Support for Intelligence Officers
The goal is to **automate mundane tasks** for intelligence officers, aiming for **5-10% improvements** in their processes. The work is **context-driven**, and the team is providing a framework to **enhance efficiency**. A legacy project rewrite was necessary, leading to a fresh start with a focus on **best practices** and **automated releases**.

### The Importance of Internal Code Standards and Modular Architecture
The perception of a team's success is influenced by both **internal standards** and **external expectations**. Modulith's architecture verification is crucial for **enforcing code standards** and **preventing unintentional access violations**. While traditional tools like Gradle and Maven can help with module segregation, Modulith offers a **more effective way to apply architectural constraints** and **maintain code integrity**.

### The Challenges of Implementing Modulith Architecture
The speaker discusses the use of J molecules for layout architecture and class/module organization, emphasizing the **potential pitfalls of overcomplicating the architecture**. They provide an example of feature flagging and argue that the **complex architecture they chose was unnecessary**. The speaker also highlights the struggle with Modulith's **lack of support for nested modules** and the **importance of team alignment in a distributed environment**, ultimately leading to a commitment to **semantic release notes and automated releases**.

### Lessons Learned from Using Modulith
Using Kodin and pre-commit hooks led to **unexpected commit breaks**, prompting the team to focus on **better communication and documentation**. The introduction of Arch Unit through Modulith helped enforce architectural rules, such as **avoiding named interfaces**, and offered a unique **freezing rule for managing test violations**. The team also discovered the power of Spring application events for module communication, but missed the opportunity to leverage the annotation's **async and transactional features for event saving during JVM restarts**.

### Challenges with Event-Driven Downloads
The team implemented an event-driven mechanism to download events from multiple providers, but encountered **duplicate events in production** due to ineffective scheduling and locking. The issue was traced to **milliseconds of difference between hosts**, leading to independent event triggers. As a workaround, the team **reduced the number of nodes** until the issue was resolved, and they considered **splitting the event providers into microservices** for better scalability.

### The Impact of Spring Modulith on Development
The system is currently not prioritizing queuing or database integration for user presentation, as the **added infrastructure costs are not justified**. The codebase has significantly reduced from **183 database tables**, and code coverage has improved, with developers aiming for **90%**. The use of Spring Modulith has become seamless in the workflow, with developers **no longer violating rules** and finding it **beneficial for the development process**.

### Building a Successful Development Team: The Modulith Concept
The speaker shares their journey in getting the development team to buy into the modulith concept, which took about **three to four months**. They emphasize the importance of **making mistakes and sharing knowledge with the community** to foster growth. The speaker believes that the modulith approach can be applied to both **greenfield projects and legacy codebases**, encouraging **gradual improvement**.

### Embracing Spring Modulith: Lessons Learned from a Development Journey
* 🚀 The speaker expresses excitement about the Spring Modulith project, highlighting it as a **long-awaited discovery** that promises **significant improvements** in software development processes.
* 💻 Tim, the engineering lead at km, shares insights from their experience with Spring Modulith, emphasizing that their session will focus on the **mistakes made during initial implementation** rather than the successes of others.
* 🔍 The intelligence team at km conducts security assessments, which include evaluating the **safety of air travel routes and accommodations**, demonstrating the **importance of their work in real-world scenarios**.
* 📊 Tim recounts the challenges faced when tasked with rewriting a legacy project, ultimately concluding that the **codebase was beyond saving and needed a complete overhaul**, leading to a **difficult conversation with stakeholders**.
* 🛠 The team adopted Spring Boot and Java for the new project, implementing **best practices to avoid past mistakes**, while also acknowledging the **pressure and unpredictability** that previously plagued their development process.
* 📈 As they progressed with Spring Modulith, they learned the value of **maintaining architectural integrity** and the importance of **adhering to modular arrangements**, which helped **prevent bad coding practices**.
* 🔄 Tim highlights the journey of integrating application events into their workflow, which inadvertently became a **standard practice**, showcasing the **adaptability of the team to new methodologies**.
* 💡 In conclusion, Tim encourages others to **share their experiences and mistakes** with Spring Modulith, fostering a **community of learning and improvement** in software development practices.

Spring Modulith And I: An Apprenticeship In Team Building (SpringOne 2024)

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