Enable ASP.NET ASMX web service for HTTP POST / GET requests
Try to declare UseHttpGet over your method.
[ScriptMethod(UseHttpGet = true)]
public string HelloWorld()
{
return "Hello World";
}
Actually, I found a somewhat quirky way to do this. Add the protocol to your web.config, but inside a location element. Specify the webservice location as the path attribute, like so:
<location path="YourWebservice.asmx">
<system.web>
<webServices>
<protocols>
<add name="HttpGet"/>
<add name="HttpPost"/>
</protocols>
</webServices>
</system.web>
</location>