receiving POST encoded in JSON

We are planing to wor with a company that will send us data as POST in
json format.
CGIDEV seems to ignore this data. With another company I used
QtmhRdStin, but I wonder if there is an easier way to read it.

I installed YAJL from Scot's site, but it seems that is great to create
json and to parse it, but I did not find how to receive it.

According to this: http://www.w3.org/TR/html-json-forms/ browsers will
be able to send json encode data.

Here is part of the document they send me.

Recurso: Pago (POST / JSON)
Pedido

Nombre Campo Tipo Longitud Descripción
codServicio String 5
tipoTrx Num 2 03 = Pago
usuario String 20
password String 20
nroFactura Num 15
importe String 15,2 Ej.: 10.000 = 000000001000000
moneda String 1 1= Guaraní, 2= Dólar.
medioPago Num 1 1=Efectivo, 2=Cheque
codTransaccion Num 10 Identificador único de la transacción.

{
"usuario": "test",
"password": "*134*",
"nroFactura": "60",
"moneda": "1",
"importe": "335500",
"codTransaccion": "0012929861"
}

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