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Real-time — SSE & WebSocket

Helena speaks two real-time protocols in addition to request/response HTTP. Both are hand-rolled on the Go standard library — no third-party dependency.

Server-Sent Events (SSE)

A one-way stream of events over HTTP (text/event-stream).

  1. Enter the endpoint URL as usual.
  2. Click the Stream button (next to Send).

Helena opens the stream with Accept: text/event-stream, reads the body incrementally, and appends each event to the response Body view live, with a running event count in the status line. The Stream button becomes Stop while the stream is open — click it (or send a new request) to end the stream.

Each event is rendered with its optional event: type and id: followed by the data payload. The parser follows the WHATWG interpretation algorithm: multi-line data: accumulation, \n / \r / \r\n line endings, comments, and the persistent last-event-id.

Note

A stream and a normal Send are mutually exclusive — stop one before starting the other.

WebSocket

A persistent, bidirectional connection (RFC 6455).

  1. Enter a ws:// or wss:// URL.
  2. Click Send (or press Enter in the URL field).

Because the URL scheme is ws/wss, Helena opens a WebSocket session dialog instead of doing an HTTP request:

  • It dials the resolved URL and runs the opening handshake (verifying the server's Sec-WebSocket-Accept). Your request's enabled headers — e.g. an Authorization header — are carried into the upgrade, with {{variables}} resolved.
  • Received messages appear in the transcript prefixed ←; messages you type and Send appear prefixed →.
  • Pings from the server are answered with pongs automatically; fragmented messages are reassembled.
  • Close the dialog to close the connection.

Text frames are shown as text; binary frames are summarized as <N binary bytes>.

Hand-rolled, spec-pinned

The RFC 6455 frame codec (masking, the 7/16/64-bit length encodings, control frames) and the Sec-WebSocket-Accept derivation are implemented from the spec and pinned to its own §5.7 and §1.3 examples. gRPC, by contrast, can't be hand-rolled on this footprint and is intentionally not bundled.