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Fetching a URL

Problem

You want to get the web page stored at a URL (web address), such as http://schematics.sourceforge.net/

Solution

The url.ss library in the net collection provides support for opening URLs. The following program opens a URL and displays the HTML that makes up the HTTP body.

(require (lib "url.ss" "net"))

(display-pure-port
 (get-pure-port
  (string->url "http://schematics.sourceforge.net/")))

Discussion

If you want to retain the HTTP headers use the get-impure-port function.

(require (lib "url.ss" "net"))

(get-impure-port
 (string->url "http://schematics.sourceforge.net/"))

To get the headers from an impure-port, you purify it.

(require (lib "url.ss" "net"))

(purify-port
 (get-impure-port
  (string->url "http://schematics.sourceforge.net/")))

If you're behind a proxy server, you'll need to set a proxy with current-proxy-servers, which also can be called without arguments to display the current settings:

> (current-proxy-servers '(("http" "proxy.example.com" 8101)))
> (current-proxy-servers)
(("http" "proxy.example.com" 8101))

To retrieve a URL using the HTTPS protocol, see WebFetchingHttpsUrl.

Note: query string separator

> If you want the bits at the end to use & instead of ; there you'll
> want to do this:
>
> (require (lib "url.ss" "net")
> (lib "uri-codec.ss" "net"))
>
> (current-alist-separator-mode 'amp)
>
> (url->string
> (string->url "http://uk.old.finance.yahoo.com/d/quotes.csv?s=@%5EFTMC&f=sl1d1t1c1ohgv&e=.csv"))
>

See also http://pre.plt-scheme.org/plt/collects/net/doc.txt

-- StephenDeGabrielle - 12 Jul 2007

-- JensAxelSoegaard

-- GordonWeakliem - 20 Apr 2004