Interface IWorkflowOperationMiddleware

Namespace

WorkflowForge.Abstractions

Assembly

WorkflowForge.dll

Middleware that executes at the operation level (wraps individual operation execution). Operation middleware executes INSIDE the foundry pipeline for each operation.

Execution Order:

Operation middleware wraps each operation execution in a Russian Doll pattern:

OperationMiddleware1 (outermost - first added)
  → OperationMiddleware2
    → OperationMiddleware3 (innermost - last added)
      → OPERATION EXECUTES
    ← OperationMiddleware3
  ← OperationMiddleware2
← OperationMiddleware1

Common Use Cases:

• Error Handling: Catch and log operation exceptions
• Timing: Measure operation execution time
• Logging: Log operation start/completion with context
• Validation: Validate operation inputs/outputs
• Retry Logic: Retry failed operations with backoff
• Caching: Cache operation results
• Authorization: Check permissions before executing operation

public interface IWorkflowOperationMiddleware

Remarks

Unlike IWorkflowMiddleware which executes once per workflow, operation middleware executes for EACH operation in the workflow. This allows fine-grained control over individual operation behavior.

Methods

ExecuteAsync(IWorkflowOperation, IWorkflowFoundry, object?, Func<CancellationToken, Task<object?>>, CancellationToken)

Executes the operation middleware logic.

Task<object?> ExecuteAsync(IWorkflowOperation operation, IWorkflowFoundry foundry, object? inputData, Func<CancellationToken, Task<object?>> next, CancellationToken cancellationToken = default)

Parameters

operation IWorkflowOperation

The operation being executed.

foundry IWorkflowFoundry

The foundry context providing properties, logger, and services.

inputData object

Input data passed to the operation.

next Func<CancellationToken, Task<object>>

Delegate to invoke the next middleware in the pipeline or the operation itself. Call this to continue the operation execution. Not calling this will short-circuit the operation.

cancellationToken CancellationToken

Cancellation token for the operation execution.

Returns

Task<object>

A task representing the operation execution result. The result can be null or any object depending on the operation.

Remarks

Middleware should:

• Call next(cancellationToken) to continue operation execution
• Handle exceptions appropriately (log, transform, or rethrow)
• Clean up resources in finally blocks
• Respect cancellation tokens
• Preserve operation results unless intentionally transforming them

Example implementation:

public async Task<object?> ExecuteAsync(
    IWorkflowOperation operation,
    IWorkflowFoundry foundry,
    object? inputData,
    Func<CancellationToken, Task<object?>> next,
    CancellationToken cancellationToken)
{
    // Pre-execution logic
    Logger.LogInformation("Starting operation: {Name}", operation.Name);

    try
    {
        // Execute operation
        var result = await next(cancellationToken).ConfigureAwait(false);

        // Post-execution logic (success)
        Logger.LogInformation("Operation completed: {Name}", operation.Name);
        return result;
    }
    catch (Exception ex)
    {
        // Post-execution logic (failure)
        Logger.LogError(ex, "Operation failed: {Name}", operation.Name);
        throw;
    }
}

Exceptions

OperationCanceledException

Thrown when the operation execution is cancelled.