HTTP proxies

[Devin Asay]

So Trevor, when, if ever, is the HTTPProxy property in LiveCode useful?

On Aug 20, 2013, at 12:26 PM, Trevor DeVore wrote:

> On Tue, Aug 20, 2013 at 1:22 PM, Devin Asay <devin_asay at byu.edu> wrote:
> 
>> I am a neophyte when it comes to proxy servers. My application phones home
>> on occasion via HTTP requests (mostly GET but some PUT) to get content
>> update updates and such. One user has reported that this fails because the
>> application isn't set up to use his university's proxy server.
>> 
>> I found the HTTPProxy property in the dictionary. Is it sufficient to give
>> users a way in my application to enter their HTTP proxy server address?
>> This is also a point of confusion to me. I thought that the HTTP proxy was
>> an OS setting that users set up when setting their network settings. Can
>> anyone point me in the right direction?
>> 
> 
> Ah, proxy servers. When it comes to proxy servers, what will work is highly
> dependent on how the proxy server is set up. Here are a couple of scenarios
> to consider. I have come across all of them while working with customers.
> 
> 1) The user has a predefined proxy IP address stored in the OS. No
> authentication required.
> 
> 2) The user has a predefined proxy IP address with a username/password that
> they need to enter. The proxy server might use Basic or Digest
> authentication.
> 
> 3a) The proxy server is determined by a PAC file that lives on their
> internal network. This PAC file is javascript that determines which proxy
> server should be used based on the URL that is being requested.
> 
> 3b) You might have to find a PAC file on the network using the WPAD
> detection protocol.
> 
> 4) NTLM authentication may be required in which case you need an external
> to handle the various handshakes between proxy server and your app.
> 
> In addition, if you are requesting urls using https then you need support
> for the CONNECT protocol. libURL does not support this but curl does (if
> you have a binary that was compiled correctly).
> 
> So basically proxy servers are a major pain to deal with.
> 
> If the user is behind a static proxy server IP address then you could
> create a dialog allowing them to enter that address. If the proxy needs a
> username/password then you also have to determine the auth type (e.g.
> Basic, Digest, …).
> 
> For PAC files it becomes more complicated as does NTLM.
> 
> The GLX App Framework has a version of libURL that can support everything
> except for https connections through proxy servers (NTLM is handled by an
> external That Chipp and Chris provided). I've had to resort to a custom
> version of libURL built around curl for CONNECT support, but that isn't
> publicly available.
> 
> If you download the latest GLX Application Framework code then you can get
> to the internet library and the routines for processing PAC/finding PAC (in
> the glxappFramework stack file).
> 
> Here are some docs I have for it:
> 
> http://www.bluemangolearning.com/revolution/docs/glxapp_framework/api_docs/Documents/stack_glxapplicationFramework_package_10810598858276329711010032801141111201213283117112112111114116.htm
> 
> http://revolution.screenstepslive.com/s/revolution/m/glxapp/c/1950
> 
> -- 
> Trevor DeVore
> Blue Mango Learning Systems
> www.clarify-it.com    -    www.screensteps.com
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Devin Asay
Office of Digital Humanities
Brigham Young University