purpose of socket.shutdownOutput()

Question

I am using the below code to send data to a tcp server. I am assuming that I need to use socket.shutdownOutput() to properly indicate that the client is done sending the request. Is my assumption correct? If not please let me know the purpose of shutdownOutput(). Also appreciate any further optimizations I can make.

Client

def address = new InetSocketAddress(tcpIpAddress, tcpPort as Integer)
clientSocket = new Socket()
clientSocket.connect(address, FIVE_SECONDS)
clientSocket.setSoTimeout(FIVE_SECONDS)

// default to 4K when writing to the server
BufferedOutputStream outputStream = new BufferedOutputStream(clientSocket.getOutputStream(), 4096)

//encode the data
final byte[] bytes = reqFFF.getBytes("8859_1")
outputStream.write(bytes,0,bytes.length)
outputStream.flush()
clientSocket.shutdownOutput()

Server

ServerSocket welcomeSocket = new ServerSocket(6789)

while(true)
{
    println "ready to accept connections"
    Socket connectionSocket = welcomeSocket.accept()
    println "accepted client req"
    BufferedInputStream inFromClient = new BufferedInputStream(connectionSocket.getInputStream())
    BufferedOutputStream outToClient = new BufferedOutputStream(connectionSocket.getOutputStream())
    ByteArrayOutputStream bos=new ByteArrayOutputStream()

    println "reading data byte by byte"  
    byte b=inFromClient.read()    
    while(b!=-1)
    {        
       bos.write(b)
       b=inFromClient.read()
    }
    String s=bos.toString()

    println("Received request: [" + s +"]")   

    def resp = "InvalidInput"
    if(s=="hit") { resp = "some data" }

    println "Sending resp: ["+resp+"]"

    outToClient.write(resp.getBytes());
    outToClient.flush()
}

Answer 1

Socket.shutdownOutput() means that the client is finished sending any data through the TCP connection. It will send the remaining data followed by a termination sequence which will completely close its OUTGOING connection. It is not possible to send any further data, which will also indicate to your program that the request is completely finished. So its recommended if you are sure you don't have to send any more data.

But it's not needed to indicate that the request is finished (you don't have to open/close the output all the time if you have multiple requests), there are other ways.