Skip to main content

Head

procedure Head(const aURL: string);

Example​

procedure ScriptEvent(var Value: variant);
begin
  Http.Head('https://api.example.invalid/archive/current');
  Value := Http.Response.ContentLength;
end;

Usage​

Sends a synchronous HEAD request without a response-body destination while retaining status and header metadata on the response facade.

Additional Technical Info​

Head selects hmHead, stores aURL, and calls Indy's HEAD overload without a response-content stream. Response.Content is cleared before the request and remains empty; status and response headers are still read from the underlying Indy response.

The method also supplies no request body. Pending Content is ignored and then normally cleared during finalisation.

Servers are expected to return the same header fields they would have selected for GET, while omitting the content. A reported Content-Length describes the selected representation, not bytes stored in Response.Content. Velox does not issue a follow-up GET, validate metadata consistency or implement cache logic.

HTTP error statuses normally remain inspectable. Operational failures can raise; response metadata can be stale if no new response was received. Redirects, cookies, authentication, proxy and SSL settings follow the shared client lifecycle.

Use HEAD only when the origin supports it correctly. It is safe/idempotent by specification, but remote behavior is outside Velox's control. The call blocks, URLs are unrestricted by this method, and the reviewed local SSL path does not enable peer-certificate verification.

External references

Created 2026-07-15