async.clj

(send! [ch message] [ch message options]
  "Send a message to the channel, asynchronously.

   `message` can either be a String or byte[]. If it is a String, it will be
    encoded to the character set of the response for HTTP streams, and as UTF-8
    for WebSockets.

   The following options are supported [default]:

   * :close? - if `true`, the channel will be closed when the send completes.
     Setting this to `true` on the first send to an HTTP stream channel
     will cause it to behave like a standard HTTP response, and *not* chunk
     the response. [false]
   * :status - the HTTP status of the response. Used to override the status
     returned from the handler that called `as-channel` for HTTP streams.
     Ignored if this is not the first send to the channel. [nil]
   * :headers - the HTTP headers of the response. Used to override the headers
     returned from the handler that called `as-channel` for HTTP streams.
     Ignored if this is not the first send to the channel. [nil]
   * :on-complete - `(fn [throwable] ...)` - called when the send
     attempt has completed. The success of the attempt is signaled by the
     passed value, i.e. if throwable is nil. If the error requires the
     channel to be closed, the [[as-channel]] :on-close callback will
     also be invoked. If this callback throws an exception, it will be
     reported to the [[as-channel]] :on-error callback [`#(when % (throw %))`]

   Returns nil if the channel is closed when the send is initiated, true
   otherwise. If the channel is already closed, :on-complete won't be
   invoked.")