Trait WorkflowHandler 

pub trait WorkflowHandler: Send + Sync {
    // Required methods
    fn name(&self) -> &str;
    fn execute<'a>(&'a self, ctx: &'a mut WorkflowContext) -> HandlerFuture<'a>;

    // Provided methods
    fn version(&self) -> Option<&str> { ... }
    fn category(&self) -> Option<&str> { ... }
    fn input_schema(&self) -> Option<Value> { ... }
    fn default_labels(&self) -> HashMap<String, String> { ... }
    fn describe(&self) -> WorkflowInfo { ... }
}

A dynamic workflow handler with context-aware step chaining.

Implement this trait to define workflows where each step can use the output of previous steps. Register handlers with Engine::register and execute them by name.

Why Pin<Box<dyn Future>> instead of async fn?

The handler must be object-safe (dyn WorkflowHandler) to allow registering different handler types in the engine’s registry.

Required Methods

fn name(&self) -> &str

The workflow name used for registration and lookup.

fn execute<'a>(&'a self, ctx: &'a mut WorkflowContext) -> HandlerFuture<'a>

Execute the workflow with the given context.

The context provides shell, http, and agent methods that automatically persist each step.

Errors

Return EngineError if any step fails. The engine will mark the run as Failed and record the error.

Provided Methods

fn version(&self) -> Option<&str>

Handler version string, used to trace which code version produced a run.

Override this to return a meaningful version (semver, git SHA, build hash, etc.). The default is None.

fn category(&self) -> Option<&str>

Optional /-separated category path used to group workflows in the UI tree.

Return a value like "data/etl" to place the workflow under data → etl. The default is None (uncategorized).

Validation (empty segments, leading or trailing /, //, whitespace segments) is enforced at registration time by Engine::register.

fn input_schema(&self) -> Option<Value>

Return a JSON Schema describing the expected input payload.

When present, the dashboard renders a dynamic form from this schema and the engine validates the payload before creating a run. The default is None (no schema, free-form payload).

fn default_labels(&self) -> HashMap<String, String>

Labels automatically applied to every run of this workflow.

These are merged with any labels provided at run creation time. User-provided labels take precedence over defaults.

fn describe(&self) -> WorkflowInfo

Return metadata about this workflow (description, source code).

Override this to provide a description and source code for the dashboard UI. The default returns an empty description with no source but propagates WorkflowHandler::category, WorkflowHandler::version, WorkflowHandler::input_schema, and WorkflowHandler::default_labels.

Implementors