http man page on DigitalUNIX

Man page or keyword search:  
man Server   12896 pages
apropos Keyword Search (all sections)
Output format
DigitalUNIX logo
[printable version]

Http(n)			     Tcl Built-In Commands		       Http(n)


       Http - Client-side implementation of the HTTP/1.0 protocol.

       package require http ?2.0?

       ::http::config ?options?

       ::http::geturl url ?options?

       ::http::formatQuery list

       ::http::reset token

       ::http::wait token

       ::http::status token

       ::http::size token

       ::http::code token

       ::http::data token

       The  http  package  provides  the client side of the HTTP/1.0 protocol.
       The package implements the GET, POST, and HEAD operations of  HTTP/1.0.
       It  allows configuration of a proxy host to get through firewalls.  The
       package is compatible with the Safesock security policy, so it  can  be
       used  by	 untrusted applets to do URL fetching from a restricted set of

       The ::http::geturl procedure does  a  HTTP  transaction.	  Its  options
       determine  whether  a GET, POST, or HEAD transaction is performed.  The
       return value of ::http::geturl is a token  for  the  transaction.   The
       value is also the name of an array in the ::http namespace
	that  contains	state information about the transaction.  The elements
       of this array are described in the STATE ARRAY section.

       If the -command option is specified, then the HTTP operation is done in
       the  background.	  ::http::geturl  returns immediately after generating
       the HTTP request and the callback is invoked when the transaction  com‐
       pletes.	 For  this  to work, the Tcl event loop must be active.	 In Tk
       applications this is always true.  For pure-Tcl applications, the call‐
       er can use ::http::wait after calling ::http::geturl to start the event

       ::http::config ?options?
	      The ::http::config command is used to set and query the name  of
	      the  proxy  server and port, and the User-Agent name used in the
	      HTTP requests.  If no options are specified,  then  the  current
	      configuration  is	 returned.  If a single argument is specified,
	      then it should be one of the flags  described  below.   In  this
	      case  the current value of that setting is returned.  Otherwise,
	      the options should be a set of flags and values that define  the

	      -accept mimetypes
		     The  Accept  header  of the request.  The default is */*,
		     which means that all types	 of  documents	are  accepted.
		     Otherwise	you  can supply a comma separated list of mime
		     type patterns that you are willing to receive.  For exam‐
		     ple, "image/gif, image/jpeg, text/*".

	      -proxyhost hostname
		     The name of the proxy host, if any.  If this value is the
		     empty string, the URL host is contacted directly.

	      -proxyport number
		     The proxy port number.

	      -proxyfilter command
		     The  command  is  a  callback   that   is	 made	during
		     ::http::geturl  to determine if a proxy is required for a
		     given host.  One argument, a host name, is added to  com‐
		     mand  when	 it  is	 invoked.  If a proxy is required, the
		     callback should return a two element list containing  the
		     proxy server and proxy port.  Otherwise the filter should
		     return an empty list.  The	 default  filter  returns  the
		     values  of the -proxyhost and -proxyport settings if they
		     are non-empty.

	      -useragent string
		     The value of the User-Agent header in the	HTTP  request.
		     The default is "Tcl http client package 2.0."

       ::http::geturl url ?options?
	      The  ::http::geturl   command is the main procedure in the pack‐
	      age.  The -query option causes a POST operation and  the	-vali‐
	      date  option causes a HEAD operation; otherwise, a GET operation
	      is performed.  The ::http::geturl command returns a token	 value
	      that  can be used to get information about the transaction.  See
	      the STATE ARRAY section for details.  The ::http::geturl command
	      blocks until the operation completes, unless the -command option
	      specifies a callback that is invoked when the  HTTP  transaction
	      completes.  ::http::geturl takes several options:

	      -blocksize size
		     The  blocksize  used  when reading the URL.  At most size
		     bytes are read at once.  After each block, a call to  the
		     -progress callback is made.

	      -channel name
		     Copy  the	URL contents to channel name instead of saving
		     it in state(body).

	      -command callback
		     Invoke callback after  the	 HTTP  transaction  completes.
		     This  option causes ::http::geturl to return immediately.
		     The callback gets an  additional  argument	 that  is  the
		     token  returned  from  ::http::geturl.  This token is the
		     name of an array that is described	 in  the  STATE	 ARRAY
		     section.  Here is a template for the callback:
			    proc httpCallback {token} {
				upvar #0 $token state
				# Access state as a Tcl array

	      -handler callback
		     Invoke  callback  whenever	 HTTP  data  is	 available; if
		     present, nothing else will be done with  the  HTTP	 data.
		     This  procedure gets two additional arguments: the socket
		     for  the  HTTP  data  and	 the   token   returned	  from
		     ::http::geturl.   The token is the name of a global array
		     that is described in the STATE ARRAY section.  The proce‐
		     dure  is expected to return the number of bytes read from
		     the socket.  Here is a template for the callback:
			    proc httpHandlerCallback {socket token} {
				upvar #0 $token state
				# Access socket, and state as a Tcl array
				(example: set data [read $socket 1000];set nbytes [string length $data])
				return nbytes

	      -headers keyvaluelist
		     This option is used to add	 extra	headers	 to  the  HTTP
		     request.	The  keyvaluelist argument must be a list with
		     an even number of elements that  alternate	 between  keys
		     and  values.   The	 keys become header field names.  New‐
		     lines are stripped from the values so the	header	cannot
		     be corrupted.  For example, if keyvaluelist is Pragma no-
		     cache then the following header is included in  the  HTTP
		     Pragma: no-cache

	      -progress callback
		     The callback is made after each transfer of data from the
		     URL.  The callback gets three additional  arguments:  the
		     token from ::http::geturl, the expected total size of the
		     contents from the Content-Length meta-data, and the  cur‐
		     rent  number  of  bytes transferred so far.  The expected
		     total size may be unknown, in which case zero  is	passed
		     to	 the  callback.	  Here	is a template for the progress
			    proc httpProgress {token total current} {
				upvar #0 $token state

	      -query query
		     This flag causes ::http::geturl to do a POST request that
		     passes  the  query	 to the server. The query must be a x-
		     url-encoding formatted  query.   The  ::http::formatQuery
		     procedure can be used to do the formatting.

	      -timeout milliseconds
		     If	 milliseconds is non-zero, then ::http::geturl sets up
		     a timeout to occur after the  specified  number  of  mil‐
		     liseconds.	  A timeout results in a call to ::http::reset
		     and to the -command callback, if specified.   The	return
		     value  of	::http::status	is timeout after a timeout has

	      -validate boolean
		     If boolean is non-zero, then ::http::geturl does an  HTTP
		     HEAD  request.   This  request  returns  meta information
		     about the URL, but the contents are  not  returned.   The
		     meta  information	is available in the state(meta)	 vari‐
		     able after the transaction.  See the STATE ARRAY  section
		     for details.

       ::http::formatQuery key value ?key value ...?
	      This  procedure  does x-url-encoding of query data.  It takes an
	      even number of arguments that are the keys  and  values  of  the
	      query.  It encodes the keys and values, and generates one string
	      that has the proper & and = separators.  The result is  suitable
	      for the -query value passed to ::http::geturl.

       ::http::reset token ?why?
	      This command resets the HTTP transaction identified by token, if
	      any.  This sets the state(status) value to why,  which  defaults
	      to reset, and then calls the registered -command callback.

       ::http::wait token
	      This  is	a  convenience procedure that blocks and waits for the
	      transaction to  complete.	  This	only  works  in	 trusted  code
	      because it uses vwait.

       ::http::data token
	      This  is	a  convenience procedure that returns the body element
	      (i.e., the URL data) of the state array.

       ::http::status token
	      This is a convenience procedure that returns the status  element
	      of the state array.

       ::http::code token
	      This is a convenience procedure that returns the http element of
	      the state array.

       ::http::size token
	      This is a convenience procedure  that  returns  the  currentsize
	      element of the state array.

       The ::http::geturl procedure returns a token that can be used to get to
       the state of the HTTP transaction in the form of a Tcl array.  Use this
       construct to create an easy-to-use array variable:
	      upvar #0 $token state
       The following elements of the array are supported:

	      body   The  contents  of	the  URL.   This  will be empty if the
		     -channel  option  has  been  specified.   This  value  is
		     returned by the ::http::data command.

		     The  current  number of bytes fetched from the URL.  This
		     value is returned by the ::http::size command.

	      error  If defined, this is the error string seen when  the  HTTP
		     transaction was aborted.

	      http   The  HTTP	status	reply  from the server.	 This value is
		     returned by the ::http::code command.  The format of this
		     value is:
			    code string
		     The  code	is  a  three-digit  number defined in the HTTP
		     standard.	A code of 200 is OK.  Codes beginning  with  4
		     or	 5  indicate errors.  Codes beginning with 3 are redi‐
		     rection errors.  In  this	case  the  Location  meta-data
		     specifies	a new URL that contains the requested informa‐

	      meta   The HTTP protocol returns meta-data  that	describes  the
		     URL  contents.   The meta element of the state array is a
		     list of the keys and values of the meta-data.  This is in
		     a	format useful for initializing an array that just con‐
		     tains the meta-data:
			    array set meta $state(meta)
		     Some of the meta-data keys are listed below, but the HTTP
		     standard  defines more, and servers are free to add their

			    The type of the URL	 contents.   Examples  include
			    text/html,	image/gif,  application/postscript and

			    The advertised size of the contents.   The	actual
			    size  obtained  by	::http::geturl is available as

			    An alternate URL that contains the requested data.

	      status Either ok, for successful	completion,  reset  for	 user-
		     reset,  or	 error	for  an	 error	condition.  During the
		     transaction this value is the empty string.

		     A copy of the Content-Length meta-data value.

	      type   A copy of the Content-Type meta-data value.

	      url    The requested URL.

       # Copy a URL to a file and print meta-data proc ::http::copy { url file
       {chunk 4096} } {
	   set out [open $file w]
	   set	token  [geturl $url -channel $out -progress ::http::Progress \
	 -blocksize $chunk]
	   close $out
	   # This ends the line started by http::Progress
	   puts stderr ""
	   upvar #0 $token state
	   set max 0
	   foreach {name value} $state(meta) {	 if {[string length  $name]  >
       $max}  {	       set max [string length $name]   }   if {[regexp -nocase
       ^location$ $name]} {	  # Handle URL	redirects	  puts	stderr
       "Location:$value"       return [copy [string trim $value] $file $chunk]
	   incr max
	   foreach {name value} $state(meta) {	 puts [format "%-*s  %s"  $max
       $name: $value]

	   return $token } proc ::http::Progress {args} {
	   puts -nonewline stderr . ; flush stderr }

       safe(n), socket(n), safesock(n)

       security policy, socket

Tcl				      8.0			       Http(n)

List of man pages available for DigitalUNIX

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
Vote for polarhome
Free Shell Accounts :: the biggest list on the net