Attach stdin of docker container via websocket - api

Question

I am using the chrome websocket client extension to attach to a running container calling the Docker remote API like this:
ws://localhost:2375/containers/34968f0c952b/attach/ws?stream=1&stdout=1
The container is started locally from my machine executing a jar in the image that waits for user input. Basically I want to supply this input from an input field in the web browser.
Although I am able to attach using the API endpoint, I am encountering a few issues - probably due to my lackluster understanding of the ws endpoint as well as the bad documentation - that I would like to resolve:
1) When sending data using the chrome websocket client extension, the frame appears to be transmitted over the websocket according to the network inspection tool. However, the process running in the container waiting for input only receives the sent data when the websocket connection is closed - all at once. Is this standard behaviour? Intuitively you would expect that the input is immediately sent to the process.
2) If I attach to stdin and stdout at the same time, the docker deamon gets stuck waiting for stdin to attach, resulting in not being able to see any output:
[debug] attach.go:22 attach: stdin: begin
[debug] attach.go:59 attach: stdout: begin
[debug] attach.go:143 attach: waiting for job 1/2
[debug] server.go:2312 Closing buffered stdin pipe
[error] server.go:844 Error attaching websocket: use of closed network connection
I have solved this opening two separate connections for stdin and stdout, which works, but is really annoying. Any ideas on this one?
Thanks in advance!