Question: I need to send an AJAX request to, for example, port 8080 where a daemon is running there.

Answer: 
You cannot `POST` information cross domain, subdomain, or port number. You can however use JSONP if you have access to both the daemon *and* the requesting site. If data needs to be returned, then the `daemon` needs to support a `callback` query parameter and return it properly formatted.

Pass the information to the daemon:

```
$.getJSON('http://domain.com:8080/url/here?callback=?', {
  key: 'value',
  otherKey: 'otherValue'
}, function(data){
     // Handles the callback when the data returns
});

```

Now just make sure your daemon handles the `callback` parameter. For instance, if `callback=mycallback` the return from the daemon (the only thing written to the page) should look like this:

For an key/value pairs:

```
mycallback( {'returnkey':'returnvalue', 'other':'data' });

```

For an array:

```
mycallback( [1,2,3] );

```

If you do not have a JSONP or similar mechanism in place, you cannot communicate cross domain using jQuery.
This counts as a different origin, even though you have it on the same box, just different port. 

If you are targetting mostly new browsers like FireFox 3.5 and up, you can try to add `Access-Control` headers to your application in another port and allow to call from your default app pool. Information about access control headers can be found here: <https://developer.mozilla.org/en/HTTP_access_control>

IE also implements it (again, in using a different ACTIVEX control, why so?): <http://blogs.msdn.com/ie/archive/2009/01/14/completing-access-control-support-for-xdomainrequest.aspx> and <http://msdn.microsoft.com/en-us/library/cc288060(VS.85).aspx>