Re: [racket-users] Racket Echo Server/Client hanging

[Vishal Prasad]

Jon,

Thanks!

-Vishal

On Wednesday, December 6, 2017 at 12:19:07 AM UTC-5, Jon Zeppieri wrote:
>
>
>
> On Wed, Dec 6, 2017 at 12:13 AM, Vishal Prasad  > wrote:
>
>> And this is the client:
>>
>>
>> (define (hello_socket port)
>> (define-values (in out) (tcp-connect "localhost" port))
>> (write "hello socket world\n" out)
>> (display (read in)))
>>
>>
>> The client does not receive any text back, and just hangs on the read. 
>>
>>
>> The `write` is buffered. If you add a `(flush-output out)`, it will work.
>
> - Jon 
>

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Re: [racket-users] Racket Echo Server/Client hanging

[Jon Zeppieri]

On Wed, Dec 6, 2017 at 12:13 AM, Vishal Prasad  wrote:

> And this is the client:
>
>
> (define (hello_socket port)
> (define-values (in out) (tcp-connect "localhost" port))
> (write "hello socket world\n" out)
> (display (read in)))
>
>
> The client does not receive any text back, and just hangs on the read.
>
>
> The `write` is buffered. If you add a `(flush-output out)`, it will work.

- Jon

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[racket-users] Racket Echo Server/Client hanging

[Vishal Prasad]

 

Really embarrassed I can't figure out what's going on here, but I just 
spent the last two hours banging my head against this going nowhere.


I'm trying to create a simple echo server and client in Racket.


This is the server:


(define (hello_listen port)
(define listener (tcp-listen port))
(define (loop)
(define-values (in out) (tcp-accept listener))
(thread (lambda ()
(copy-port in out)
(close-output-port out)))
(loop))
(loop))


And this is the client:


(define (hello_socket port)
(define-values (in out) (tcp-connect "localhost" port))
(write "hello socket world\n" out)
(display (read in)))


The client does not receive any text back, and just hangs on the read. 

When I write a simple client in Python however, the behavior is fine:


>>> import socket
>>> s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
>>> s.connect(('localhost', ))
>>> s.send("hi")   
2
>>> s.recv(500)
'hi' 

What am I missing here in the Racket client code?

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