developmeh
diff --git a/software-architecture/decoupling_patterns_in_ruby_protocol_handler_part1.md b/software-architecture/decoupling_patterns_in_ruby_protocol_handler_part1.md
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+title = "Decoupling Patterns in Ruby: Part 1 The Protocol Handler"
+template = "page.html"
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+
+## The Protocol Hander (The Controller)
+
+Firstly, we have a __controller__, which has one job and only one job (ADD NOTE ABOUT SRP), to act as the programmatic interface for the request and response. Think of it as a primary function or an entry point for our script. Its context is
+parameters provided by the user-agent, context provided by the protocol and method, and intent provided by the route. The question you should be asking yourself here is;
+
+> Can I process the intent based on what has been provided by the request?
+
+There are some things we must know here that represent our Buy-it-Now interface. The user we are acting upon and the product we are selling. At this stage of the request, we are only interested if those values are present and how to respond if those values are malformed or omitted.
+The controller should not do any other work! The controller or entry point doesn't care if the user exists or the product is in stock; those concerns are for our service layer.
+
+```ruby
+class BuyItNowController < ApplicationController
+  def initialize(
+    idempotency_handler: IdempotencyResponseHandler.new,
+    error_handler: BuyItNowErrorHandler.new,
+    buy_it_now_service: BuyItNowService
+  )
+    @idempotency_handler = idempotency_handler
+    @error_handler = error_handler
+    super()
+  end
+
+  def buy_it_now
+    buy_it_now_service.deliver(user_id: current_user, )
+
+    # Update product logic here...
+    render json: { message: 'Product updated successfully' }, status: :ok
+  end
+
+  def idempotency_params
+    params.require(:idemptotency_id).permit(:idempotency_id)
+  end
+
+  def product_params
+    params.require(:product).permit(:sku, :quantity)
+  end
+end
+```
+
+How did we get `current_user`
+```ruby
+# user_auth_middleware.rb
+class UserAuthMiddleware
+  def initialize(app)
+    @app = app
+  end
+
+  def call(env)
+    # valdiate session data or JWT here
+    env["HTTP_X_PROCESSED_BY_MIDDLEWARE"] = "true"
+    env
+    @app.call(env)
+  end
+end
+
+class UserAuthConstraint
+  def matches?(request)
+    request.headers["X-Processed-By-Middleware"] == "true"
+  end
+end
+
+
+# routes.rb
+constraints MiddlewareConstraint.new do
+  # Routes that require the middleware processing
+  resources :products
+end
+```