Read response from WebResponse Response Stream - http

Question

I've been playing around with some basic HTTP request response operations in an F# interactive session to try and get a better feel for the language. Everything here seems to be working as expected except when I get the response stream for my HTTP request I can never seem to read anything out of it. In the following code I get the text from the printfn line every time but the value for responseString always seems to be empty. Am I missing anything obvious?
let httpListener = new HttpListener()
httpListener.Prefixes.Add("http://*:8020/")
let getContext = Async.FromBeginEnd(httpListener.BeginGetContext, httpListener.EndGetContext)
let processRequest = async {
while true do
let! context = getContext
let request = context.Request
use requestReader = new StreamReader(request.InputStream)
let requestString = requestReader.ReadToEnd()
let response = context.Response
use streamWriter = new StreamWriter(response.OutputStream)
streamWriter.WriteLine "A response!"
response.Close()
}
httpListener.Start()
let maxThreads = 10
for n = 0 to maxThreads do
Async.Start processRequest
printfn "HttpListener started with %d maximum threads processing requests." maxThreads
let sendRequest = async {
let request = WebRequest.Create("http://localhost:8020") :?> HttpWebRequest
let postBytes = Encoding.ASCII.GetBytes("Issuing HTTP")
request.Method <- "POST"
request.ContentType <- "application/x-www-form-urlencoded"
request.ContentLength <- int64 postBytes.Length
let requestStream = request.GetRequestStream()
requestStream.Write(postBytes, 0, postBytes.Length)
requestStream.Close()
let! response = Async.FromBeginEnd(request.BeginGetResponse, request.EndGetResponse)
let responseStream = response.GetResponseStream()
use streamReader = new StreamReader(responseStream)
let responseString = streamReader.ReadToEnd()
printfn "Received the following response: %s" responseString
}
for n = 0 to maxThreads do
Async.Start sendRequest

Answer 1

you need to reduce the scope of usage for StreamWriter so it can be flushed on Dispose.
let processRequest = async {
while true do
let! context = getContext
let request = context.Request
use requestReader = new StreamReader(request.InputStream)
let requestString = requestReader.ReadToEnd()
let response = context.Response
do
use streamWriter = new StreamWriter(response.OutputStream)
streamWriter.WriteLine "A response!"
response.Close()
}