def listAllProducts = {
   // retrieve and render all products in xml format...
}

def listProductById = {
   // retrieve and render a product's detail in xml format...
}

"/products"(controller:"product", parseRequest:true) {
   action = [GET:"listAllProducts"]
}

"/products/$id"(controller:"product", parseRequest:true) {
   action = [GET:"listProductById"]
}

The requested resource (/myapp/products/1) is not available