[dzach] 2008-6-25: How can one post a message to a google Blogger blog programmatically using TCL? 

Given the popularity of Google's Blogger platform, it might be a good idea to provide some basic functionality here. Google's '''Account Authentication API''' documentation can be found at:
 http://code.google.com/apis/accounts/docs/AuthForInstalledApps.html#ClientLogin
and a guide for the API here:

http://code.google.com/apis/blogger/developers_guide_protocol.html#CreatingPublicEntries

Here is the code I've tried so far (corrected with the help of [Pat Thoyts] in the Tcler's Chat):

 namespace eval ::gpost {

 proc init {} {
	# packages http and tls are needed
	if {[catch {
		package require tls
		package req http
		} err]
	} {
		return $err
	}
	variable var
	variable login

	array set var {
		loginurl https://www.google.com/accounts/ClientLogin
		posturl http://www.blogger.com/feeds/<your-blog's-id>/posts/default
		timer_http 30000
	}

	array unset login
	array set login {
		accountType GOOGLE  
		Email <your_google_account_email>
		Passwd <your_google_account_password> 
		service blogger
		source <your_company-service-version>
	}
	::http::register https 443 ::tls::socket
	set query [eval ::http::formatQuery [array get login]]

	# by specifying the -query option http::geturl sends a POST instead of a GET request, with a Content-type: application/x-www-form-urlencoded header
	# sent the POST request
	set token [::http::geturl $var(loginurl) -timeout $var(timer_http) -query $query]

	# to see what the reply was, uncomment the next line
	#parray $token

	upvar $token state
	# store login ids for later use
	foreach line [split [http::data $token] \n] { array set login [split $line =] }
	set login(httpcode) [lindex $state(http) 1]
	::http::cleanup $token
	return $login(httpcode)
 }
 proc post args {
	# prepare ATOM XML
	variable var
	variable login
	array set data $args
	if {![info exists data(-body)] || $data(-body) eq ""} {
		return [set login(httpcode) 500]
	}
	append atom "<entry xmlns='http://www.w3.org/2005/Atom' xmlns:app='http://purl.org/atom/app#'>"
	if {[info exists data(-title)] && ($data(-title) ne "")} {
		append atom "<title type='text'>$data(-title)</title>"
	}
	append atom "<content type='xhtml'>"
	append atom $data(-body)
	append atom "</content>"
	if {[info exists data(-pubtime)] && ($data(-pubtime) ne "")} {
		append atom "<published>$var(-pubtime)</published>"
	}
	if {[info exists data(-categories)] && ($data(-categories) ne "")} {
		foreach cat $data(-categories) {
			append atom "<category scheme='http://www.blogger.com/atom/ns#' term='" $cat "' />"
		}
	}
	if {![info exists data(-draft)] || $data(-draft)} {
		append atom "<app:control><app:draft>yes</app:draft></app:control>"
	}
	if {[info exists data(-author)] && ($data(-author) ne "")} {
		append atom "<author><name>$data(author)</name>"
		if {[info exists data(-email)] && ($data(-email) ne "")} {
			append atom "<email>$data(-email)</email> "
		}
		append atom "</author>"
	}
	append atom "</entry>"
	# the encoding should be utf-8
	set atom [encoding convertto utf-8 $atom]

	# now that the post is in an ATOM XML structure, send it to google
	set token [::http::geturl $var(posturl) -timeout $var(timer_http) -query $atom -type application/atom+xml -headers [list Authorization "GoogleLogin auth=$login(Auth)"]]

	# to see what the server reply was, uncomment the next line
	parray $token

	# store http return code to be returned
	upvar $token state
	set login(httpcode) [lindex $state(http) 1]

	# free memory used
	::http::cleanup $token
	return $login(httpcode)
 }
 }; # end namespace ::gpost

A reply like:
 HTTP/1.0 200 OK
 Server: GFE/1.3
 Content-Type: text/plain 

 SID=DQAAAGgA...7Zg8CTN
 LSID=DQAAAGsA...lk8BBbG
 Auth=DQAAAGgA...dk3fA5N

should be returned by the server upon login, where '''Auth=DQAAAGgA...dk3fA5N''' is the ''Auth'' (authorization) key to use in all subsequent requests. The key is stored in array value ::gpost::login(Auth), and a code 200 is returned if the login was successful.

For a minimal post, the ''post'' command must include a ''-body'' option, so to send a post, type:
 ::gpost::post -body "This is a test"

A code 201 is returned if the post was successful.
----
!!!!!!
%|[Category Internet]|%
!!!!!!