Try this (or a variation):

CREATE OR REPLACE PROCEDURE web_get( in url long varchar )
RESULT( attr varchar(128), value long varchar )
URL '!url'
TYPE 'HTTP:GET';

and then call using:

select *
  into #temp
  from web_get( @url );

The #temp temporary table will contain a number of rows - the row with attr='body' will contain the page that you retrieved from the remote web server.

If you need to pass parameters you can either add the parameters directly to the URL (using ?p1=v1&p2=v2 etc) or add additional parameters to the web_get procedure - any parameter to the procedure which is not consumed by !parameter within the procedure declaration will automatically be encoded and added to the URL (for a HTTP:GET request) or the BODY (for a HTTP:POST request).

Example:

CREATE OR REPLACE PROCEDURE web_get_1( in url long varchar, in parm1 long varchar )
RESULT( attr varchar(128), value long varchar )
URL '!url'
TYPE 'HTTP:GET';

The web_get_1 procedure is like web_get except it will send the value of 'parm1' to the remote web server. In a similar way you can add as many parameters as you need. The parameter name(s) must be the name of the parameter that the remote web server is expecting.

Example:

CREATE OR REPLACE PROCEDURE web_get_xyz(
                      in url  long varchar,
                      in x    long varchar,
                      in y    long varchar,
                      in z    long varchar
                   )
RESULT( attr varchar(128), value long varchar )
URL '!url'
TYPE 'HTTP:GET';

The get_web_xyz procedure will encode the 'x', 'y', and 'z' parameters in the remote web server request. E.g. The statement:

select * into #temp from get_web_xyz( 'http://remote.com', 10, 20, 40 )

will result in the HTTP GET request to the URL http://remote.com?x=10&y=20&z=40

More information in the documentation on creating web service procedures.

FYI: The procedure that I keep in my toolbox (of commonly used procedures) is

CREATE OR REPLACE PROCEDURE sp_web_get (
                      in  url    long varchar,
                      in  cert   long varchar  default NULL,
                      in  proxy  long varchar  default NULL,
                      in  clport varchar(10)   default NULL
                  )
RESULT( attr varchar(128), value long varchar )
URL         '!url'
TYPE        'HTTP:GET'
CERTIFICATE '!cert'
CLIENTPORT  '!clport'
PROXY       '!proxy'
;

This procedure is the generalization of the web_get procedure show above - it allows specification of a certificate (for use with HTTPS calls), a client port (if needed to get through firewalls), and an HTTP proxy (if the site is configured to use one).