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BIG-REQUESTS extension

Raises the maximum request length from the core limit of 262140 bytes (65535 4-byte units) to a server-advertised value in the megabytes, using an extended length encoding. Needed for large image transfers and glyph uploads.

  • Module: X.require('big-requests', cb) (X name BIG-REQUESTS, version 2.0)
  • Source: lib/ext/big-requests.js · Tests: no dedicated file — enabled implicitly at connect by every test
  • Spec: bigreq.html

You normally never require this module yourself: x11.createClient enables it automatically as part of connecting, unless you opt out:

x11.createClient({ disableBigRequests: true }, (err, display) => {
    // display.max_request_length stays at the handshake value (65535)
});

x11.createClient((err, display) => {
    // BigReq enabled; typically 4194303 units (16 MiB) on Xorg/Xvfb
    console.log(display.max_request_length);
});

Requests​

Enable(cb)​

Switches this connection to the extended length encoding. cb(err, maxRequestLength) — the new maximum request length in 4-byte units. Called automatically at connect; createClient stores the result as display.max_request_length (replacing the core handshake value) before invoking your callback.

Events / errors​

None.

Notes​

  • After Enable, requests may use the extended encoding: a core length field of 0 followed by a 32-bit length. Requests up to the core limit keep the classic encoding; only oversized ones need the extended form.
  • Render's AddGlyphs/AddGlyphsFromPicture (ext/render.md) always emit the extended encoding, so they only work while BigReq is enabled (the default).
  • With disableBigRequests the extension is not required at all — no Enable request is sent and the connection keeps the core 262140-byte limit.