papers/hanzo-webhooks/sections/08-implementation.tex

\section{Implementation}


\subsection{Architecture Components}

\begin{itemize}
    \item \textbf{Event Ingestion}: Kafka for event buffering
    \item \textbf{Router}: Go service matching events to subscriptions
    \item \textbf{Delivery Workers}: Go worker pool with connection reuse
    \item \textbf{Retry Queue}: Redis sorted set keyed by delivery time
    \item \textbf{Dead Letter Queue}: PostgreSQL for failed deliveries
    \item \textbf{Monitoring}: Prometheus metrics, PagerDuty alerts
\end{itemize}

\subsection{Worker Pool}

\begin{lstlisting}[language=Go, caption=Delivery Worker]
type Worker struct {
    client    *http.Client
    queue     *DeliveryQueue
    signer    *Signer
}

func (w *Worker) Process(ctx context.Context) error {
    for {
        delivery, err := w.queue.Dequeue(ctx)
        if err != nil {
            return err
        }

        result := w.deliver(ctx, delivery)
        if result.Success {
            w.queue.Ack(delivery)
        } else {
            w.scheduleRetry(delivery, result)
        }
    }
}

func (w *Worker) deliver(ctx context.Context, d *Delivery) Result {
    body, _ := json.Marshal(d.Event)
    signature := w.signer.Sign(body, time.Now().Unix())

    req, _ := http.NewRequestWithContext(ctx, "POST", d.URL, bytes.NewReader(body))
    req.Header.Set("Content-Type", "application/json")
    req.Header.Set("X-Webhook-Signature", signature)

    resp, err := w.client.Do(req)
    if err != nil {
        return Result{Success: false, Error: err}
    }
    defer resp.Body.Close()

    return Result{Success: resp.StatusCode >= 200 && resp.StatusCode < 300}
}
\end{lstlisting}

\subsection{Connection Management}

HTTP connections are pooled and reused:

\begin{lstlisting}[language=Go, caption=HTTP Client Configuration]
client := &http.Client{
    Transport: &http.Transport{
        MaxIdleConns:        1000,
        MaxIdleConnsPerHost: 100,
        IdleConnTimeout:     90 * time.Second,
    },
    Timeout: 30 * time.Second,
}
\end{lstlisting}