Let’s be honest – writing workflows in Java can feel like a never-ending game of try-catch, nested conditions, and tedious state management. If you’ve ever had to handle retries, error recovery, or compensations, you know how quickly things get out of hand.
I got tired of that too. That’s why I built Flow DSL, a tiny library that lets you define workflows in a simple, declarative way. It’s all about focusing on what should happen in each step, not how to handle every little detail. Think of it as a storyboard for your business logic – you map out each step, and Flow DSL handles the rest.
What’s the Big Idea Behind Flow DSL?
Traditional Java workflow code is imperative – you’re telling the JVM exactly how to execute each step, which leads to cluttered, repetitive code.
Flow DSL flips the script. It borrows concepts from functional programming – map(), flatMap(), etc. – so you can focus on defining what needs to happen, step by step. Instead of dealing with nested logic and endless if-else chains, you write a clean, linear flow that’s easy to read and maintain.
Why I Built Flow DSL
Every project I worked on had the same pattern – complex workflows with retries, compensations, and error handling sprinkled all over the place. The code became a mess of nested structures and hard-to-track logic.
I thought, "What if I could just write the flow like a story – this happens, then this, then that – and let a library handle the plumbing?" That’s how Flow DSL was born. It’s all about turning your workflow logic into a series of steps without worrying about implementation details.
How Flow DSL Works – Core Features and Concepts
Let’s dive into the good stuff. Here are some of the key features that make Flow DSL tick:
1. Defining a Simple Flow:
Here’s a basic flow that transforms a string and logs the result:
Flow.of(() -> "Hello")
.map(str -> str + " World")
.map(String::toUpperCase)
.onComplete(result -> log.info("Result: " + result))
.execute(); // Outputs: HELLO WORLD
No nested structures, no clutter. Just a series of steps.
2. Error Handling with Retry and Compensation:
Let’s say you’re processing a payment and want to handle retries and rollback logic:
Flow.of(() -> paymentService.processPayment(order))
.withRetry(3)
.withCompensation(() -> paymentService.rollbackPayment(order))
.onError(error -> log.error("Payment failed", error))
.execute();
Three retries and a rollback – all in a few lines of code.
3. Parallel Execution:
Need to run multiple tasks concurrently? Easy:
Flow.parallel(
() -> inventoryService.checkStock(),
() -> paymentService.verifyFunds(),
() -> notificationService.prepareEmail()
)
.withParallelism(3)
.execute();
Flow DSL takes care of concurrency so you can focus on what’s important.
4. Context Propagation:
Share data between steps without manually passing it around:
Flow.of(() -> new Order())
.map(order -> paymentService.processPayment(order))
.map(payment -> inventoryService.updateStock(payment.getItems()))
.onComplete(result -> log.info("Order processed successfully"))
.execute();
5. Timeouts and Backpressure:
Set execution time limits and manage data throughput without complex threading logic.
6. Monitoring and Metrics:
Track the status and duration of each step, making it easy to spot bottlenecks and optimize flows.
Why Flow DSL?
Declarative API: Less boilerplate, more clarity.
Centralized Error Handling: Manage retries and compensations in a consistent way.
Context Management: Pass data across steps without manual state tracking.
Scalability: Run parallel tasks effortlessly with built-in concurrency management.
Extensibility: Easily add new steps or modify the flow without breaking everything.
How You Can Help Shape Flow DSL
Flow DSL is still a work in progress, and I’d love to get your feedback. Try it out, break it, and let me know what works and what doesn’t. Here’s how you can get involved:
Check Out the Code: GitHub Repo
Explore the Docs: Documentation
Raise Issues: Report bugs, suggest features, or ask questions.
Contribute: Have a feature in mind? Open a PR and let’s build it together.
Let’s Make Flow DSL Better – Together!
Flow DSL started as a simple experiment to make workflow management easier, but with your feedback, it can become a powerful tool for Java developers everywhere. Let me know what you think – I’d love to hear your thoughts and ideas. Let’s make Flow DSL the go-to library for declarative workflow management in Java!
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