Lua - Parsing XML from a URL

Lua - Parsing XML from a URL

I want to parse this XML
http://steamcommunity.com/id/GreenMarineValve?xml=1 with Lua 5.1, there
are some libraries like LuaXML but they do not support parsing from the
URL.
Would you give me a link to a library to do that if there is any or some
advice to achieve my goal?
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More details for those who have experience with Steam's Web API, I
basically want to convert "customURL" to Steam Community ID (steamID64),
but I see there is no other way doing it without parsing that XML file, I
could parse it from the URL if it was JSON format instead of XML.
Is there an API I'm missing which will take the customURL as a parameter
and return the communityID ? Some related links to WebAPI:
https://developer.valvesoftware.com/wiki/Steam_Web_API
https://partner.steamgames.com/documentation/webapi