I'd like to be able to make an HTTP request on the web to a specific server from my Arduino. I already have a Wireless SD Shield, and I am wondering if what I want to do is possible / what I would need to buy to make it work. From what I understand, I can plug an "add-on" shield to that with an antenna, like an XBee Wireless Transmitter. However, all examples I find on the web of such things use two Arduinos, one as a receiver and one as a transmitter. What I want is to use a single Arduino to connect wirelessly to the web and make an HTTP request.
It doesn't matter if HTTP itself is not supported, I can always create a basic client using TCP. But at the very least I need to be able to create a TCP connection and send data to the web through Wifi. Basically exactly like an Ethernet shield, but through Wifi.
Best Answer
Effectively what you have discovered (your wireless SD shield) is a method of sending serial data wirelessly, from one Arduino to another, via using xBee shield, wireless shields, etc. What you need to do is to connect to the internet. As you have ruled out ethernet and specified wifi, lets talk wifi shields.
There are a number of wifi shields available for the Arduino that you can use, though they are generally much more pricey than ethernet shields.
Here is one from sparkfun,
And another here.
Take a look at the documentation on the http://arduino.cc website for ways to write code for server connection.
Cheers.