Flows

A flow is an ordered chain of steps. Each step implements the Step<C, I, O> interface and the builder ensures that the output type of one step matches the input type of the next.

class AppendAStep implements Step<None, String, String> {
    @Override
    public String invoke(Context<None> ctx, String in) {
        return in + "A";
    }
}

class AppendBStep implements Step<None, String, String> {
    @Override
    public String invoke(Context<None> ctx, String in) {
        return in + "B";
    }
}

// make the steps available to the builder
StaticStepRepository.register(AppendAStep.class, AppendBStep.class);

Sequential execution

By default steps run one after another. Each step receives the previous result as input.

var flow = StaticFlowBuilderFactory
    .builder(String.class, String.class)
    .append(AppendAStep.class)
    .append(AppendBStep.class)
    .build();

Result<String> result = flow.invoke("");
result.getResult(); // "AB"

The invocation returns a Result that captures the outcome and any thrown exception.

Concurrent execution

Adding concurrent() switches the builder into a mode where a collection of inputs is processed in parallel using the globally configured executor.

var flow = StaticFlowBuilderFactory
    .builder(String.class, String.class)
    .append(AppendAStep.class)
    .append(AppendBStep.class)
    .concurrent()
    .build();

List<Result<String>> outputs = flow.invoke(List.of("", "C"));
// outputs.get(0).getResult() == "AB"
// outputs.get(1).getResult() == "CAB"

The returned list mirrors the input order and retains the Result for each element.