Attempts to connect to a socket on another machine and returns a stream object for the connection.
open-tcp-stream hostname service &key direction element-type errorp read-timeout timeout => stream-object
An integer or string.
A string or a fixnum.
One of
:input
,
:output
or
:io
.
base-char
or a subtype of
integer
.
A boolean.
A positive number, or
nil
.
A positive number, or
nil
.
The
open-tcp-stream
function attempts to connect to a socket on another machine and returns
stream-object
for the connection if successful. The server machine to connect to is given by
hostname
, which can be one of the following:
"www.nowhere.com"
"204.71.177.75"
#xCC47B14B
The name of the service to provide is given by
service
. If
service
is a string, the location of the file specifying the names of the services available varies, but typically on Windows 95 it is called
SERVICES
and is stored in the
Windows
directory., and on Windows NT it is the file
%SystemRoot%\system32\drivers\etc\SERVICES
The service can also be a fixnum representing the port number of the desired connection.
The direction of the connection is given by
direction
. Its default value is
:io
. The element type of the connection is determined from
element-type
, and is
base-char
by default.
If
errorp
is
nil
, failure to connect (possibly after
timeout
seconds) returns
nil
, otherwise an error is signaled.
timeout
specifies a connection timeout.
open-tcp-stream
waits for
timeout
seconds for the TCP connection to be made. If
timeout
is
nil
(the default) it does not wait. On failure,
open-tcp-stream
signals an error or returns
nil
according to the value of
errorp
. To provide a timeout for reads after the connection is made, see
read-timeout
.
read-timeout
specifies the read timeout of the stream. If it is
nil
(the default), the stream does not time out during reads, and these may hang. See socket-stream for more details. To provide a connection timeout, see
timeout
.
Unlike the other ways of creating a socket stream with SSL processing,
open-tcp-stream
does not take the
ssl-side
argument and always uses the value
:client
.
The following example opens an HTTP connection to a given host, and retrieves the root page:
(with-open-stream (http (comm:open-tcp-stream
"www.lispworks.com" 80))
(format http "GET / HTTP/1.0~C~C~C~C"
(code-char 13) (code-char 10)
(code-char 13) (code-char 10))
(force-output http)
(write-string "Waiting to reply...")
(loop for ch = (read-char-no-hang http nil :eof)
until ch
do (write-char #\.)
(sleep 0.25)
finally (unless (eq ch :eof)
(unread-char ch http)))
(terpri)
(loop for line = (read-line http nil nil)
while line
do (write-line line)))