PROCEDURE POST_Test (o_replytext out VARCHAR2
,o_return_code out INTEGER
,i_messagetext in VARCHAR2
,i_urltext in VARCHAR2
,i_timeout in INTEGER DEFAULT 60)
IS
sslreq UTL_HTTP.req; /* Secure connection request */
rsp UTL_HTTP.resp; /* Secure response */
replymessage VARCHAR2(32767); /* reply message (local) */
replyline VARCHAR2(32767); /* piece of reply message read from secure site. */
BEGIN
/* Set up wallet information for secure connection capability */
/* remove this line if you don't have wallet installed and are not using https */
-- UTL_HTTP.SET_WALLET('file:DirectoryPath','put password here');
/* Initiate request to secure site, set parameters */
sslreq := UTL_HTTP.BEGIN_REQUEST(i_urltext,'POST','HTTP/1.0');
UTL_HTTP.SET_HEADER(sslreq,'Content-Type','text/xml');
UTL_HTTP.SET_HEADER(sslreq,'Content-Length',to_char(length(i_messagetext)));
UTL_HTTP.SET_TRANSFER_TIMEOUT(i_timeout);
/* Write information over secure connection */
UTL_HTTP.WRITE_TEXT(sslreq,i_messagetext);
/* Initialize Response */
rsp:=UTL_HTTP.GET_RESPONSE(sslreq);
replymessage := '';
/* Retrieve response */
BEGIN
LOOP
UTL_HTTP.READ_LINE(rsp,replyline,TRUE);
replymessage := replymessage || replyline;
END LOOP;
UTL_HTTP.END_RESPONSE(rsp);
EXCEPTION
WHEN UTL_HTTP.END_OF_BODY THEN
UTL_HTTP.END_RESPONSE(rsp);
END;
/* Set output information */
o_replytext := replymessage;
o_return_code := 0;
EXCEPTION
WHEN OTHERS THEN
o_return_code := SQLCODE;
o_replytext := SQLERRM;
END POST_Test;

Post for HTTP 1.1 is suppose to be supported, but it doesn't work. There is a bug in utl_http that Oracle knows about, and has yet to fix.