HTTP Response from ILXPlugin

Maybe you can use the example on page 49 of this document:

https://devcentral.f5.com/DesktopModules/Downloads/API/downloadservice/DownloadFile/242?version=340

flow.client.on("data", function(buffer) {
    flow.client.end(
        "HTTP/1.0 200 OK\r\n" +
        "Server: BigIP\r\n" +
        "Connection: Keep-Alive\r\n" +
        "Content-Length: " + 4 + "\r\n\r\n" +
        "abc\n");
});    

Or you need to use flow.client.write(data);