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* async_http: an async http hack for Corona SDK *
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About
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Currently (November 3, 2010), the Corona SDK only support synchronous http requests, meaning
your app blocks while the http request is in flight. Even sound playback comes to a grinding halt.

While we wait for Corona to officially support async http, I have created a workaround based on
webpopups and AJAX. 


Usage
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Usage is as follows:

		local async_http = require("async_http")

		local function onCompleteCallback(requestURL, resultPath)
		  print("URL: " .. requestURL)
		  print("was saved to: " .. resultPath)
		end

		local function onErrorCallback(requestURL, errorMessage)
		  print("Failed to fetch URL: " .. requestURL)
		  print("errormessage is: " .. errorMessage)
		end

		async_http.request(url, 
		                   absolute_path_to_destination_file, 
						   onCompleteCallback, 
						   onErrorCallback)
	
How it works
------------			
Under the hood, async_http.request opens an off-screen webpopup, loading the async_http.html file, 
passing the requestURL via a parameter (hex encoded).

The html file uses an AJAX call to fetch the data, hex encodes it, and opens a fake URL which contains
the hex-encoded data. 

This fake URL is then intercepted by the urlRequest handler of the webpopup,
hex-decoded and passed on to the onCompleteCallback handler.

There. That wasn't so hard now, was it? :-)


Credits
-------
The html file uses the Simple AJAX Code-Kit (SACK) v1.6.1, ©2005 Gregory Wild-Smith,
www.twilightuniverse.com, licenced under a modified X11 licence, see authors website 
for more details.

The html file also uses a function to decode URL Request parameters, written by
"lobo235", which as far as I can tell, was released into the Public Domain. (http://www.netlobo.com/url_query_string_javascript.html)


Contact
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Email: niels.vanspauwen@gmail.com
Twitter: @nielsvanspauwen