papers/hanzo-webhooks/sections/01-introduction.tex

\section{Introduction}


E-commerce platforms generate continuous streams of events: orders placed, payments processed, inventory updated, customers registered. External systems---fulfillment services, accounting software, marketing platforms---require timely notification of these events to maintain synchronization. Polling-based approaches introduce latency, waste resources, and create coupling between systems.

Webhooks provide a push-based alternative: the platform notifies external systems in real-time by sending HTTP requests to configured endpoints. However, webhook delivery faces challenges:

\begin{enumerate}
    \item \textbf{Reliability}: Network failures, endpoint downtime, and timeouts
    \item \textbf{Ordering}: Events must be processed in causal order
    \item \textbf{Security}: Endpoints must verify event authenticity
    \item \textbf{Scale}: High event volumes require efficient processing
\end{enumerate}

Hanzo Webhooks addresses these challenges through event sourcing, guaranteed delivery with adaptive retry, and cryptographic signature verification.

\subsection{Contributions}

This paper contributes:

\begin{itemize}
    \item A formal model of webhook delivery with provable guarantees
    \item An adaptive retry algorithm outperforming fixed exponential backoff
    \item A signature scheme preventing replay and tampering attacks
    \item Production validation processing 2.3M events daily
\end{itemize}