BSV Arcade uses Server-Sent Events (SSE) as a lightweight, real-time bridge to track Bitcoin transaction status from submission through its entire lifecycle on the network. [1]

Core Mechanism

The Arcade service acts as an intermediary between your application and the Teranode network. It provides a streaming interface that avoids the overhead of constant client polling by pushing updates to the browser as they happen. [1, 2, 3]

  • Listening to Network Events: Arcade listens to Bitcoin network events (via libp2p gossip) and updates transaction statuses in its storage (SQLite).
  • Persistent HTTP Connection: A client initiates a connection to Arcade’s /events endpoint using a standard HTTP request.
  • Unidirectional Data Flow: Once established, Arcade pushes updates (like transaction confirmation or failure) directly to the client. The client does not send data back over this specific connection. [1, 3, 4, 5, 6]

Key Features of the SSE Implementation

  • Automatic Reconnection: If the connection drops, the browser’s EventSource API automatically reconnects. Arcade then uses the Last-Event-ID header to replay any missed events from that specific timestamp, ensuring no status updates are lost.
  • Token-Based Filtering: To ensure security and privacy, each SSE connection only receives events for transactions submitted with a matching callback token. This allows multiple users to have isolated, scoped event streams without complex authentication.
  • Efficiency: Because it uses the standard text/event-stream media type over HTTP, it is compatible with most modern browsers and network infrastructures (like firewalls) that might otherwise block more complex protocols like WebSockets. [1, 4, 7]

Typical Lifecycle

  1. Transaction Submission: You submit a transaction to Arcade via its HTTP API.
  2. Connection Setup: Your frontend connects to the SSE stream using a callback token.
  3. Real-Time Pushes: As the transaction moves from “broadcast” to “seen” and finally “mined,” Arcade pushes these status changes as individual events to the client. [1, 8]

[1] https://github.com [2] https://gokhana.medium.com [3] https://maximilian-schwarzmueller.com [4] https://amitavroy.com [5] https://blogs.embarcadero.com [6] https://medium.com [7] https://en.wikipedia.org [8] https://dev.to

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