Add non-discovery ServiceClient constructor functions.

service_client.go

@@ -2,19 +2,26 @@ package goupnp
 
 import (
 	"fmt"
+	"net/url"
 
 	"github.com/huin/goupnp/soap"
 )
 
 // ServiceClient is a SOAP client, root device and the service for the SOAP
-// client rolled into one value. The root device and service are intended to be
-// informational.
+// client rolled into one value. The root device, location, and service are
+// intended to be informational. Location can be used to later recreate a
+// ServiceClient with NewServiceClientByURL if the service is still present;
+// bypassing the discovery process.
 type ServiceClient struct {
 	SOAPClient *soap.SOAPClient
 	RootDevice *RootDevice
+	Location   *url.URL
 	Service    *Service
 }
 
+// NewServiceClients discovers services, and returns clients for them. err will
+// report any error with the discovery process (blocking any device/service
+// discovery), errors reports errors on a per-root-device basis.
 func NewServiceClients(searchTarget string) (clients []ServiceClient, errors []error, err error) {
 	var maybeRootDevices []MaybeRootDevice
 	if maybeRootDevices, err = DiscoverDevices(searchTarget); err != nil {
@@ -29,26 +36,50 @@ func NewServiceClients(searchTarget string) (clients []ServiceClient, errors []e
 			continue
 		}
 
-		device := &maybeRootDevice.Root.Device
-		srvs := device.FindService(searchTarget)
-		if len(srvs) == 0 {
-			errors = append(errors, fmt.Errorf("goupnp: service %q not found within device %q (UDN=%q)",
-				searchTarget, device.FriendlyName, device.UDN))
+		deviceClients, err := NewServiceClientsFromRootDevice(maybeRootDevice.Root, maybeRootDevice.Location, searchTarget)
+		if err != nil {
+			errors = append(errors, err)
 			continue
 		}
-
-		for _, srv := range srvs {
-			clients = append(clients, ServiceClient{
-				SOAPClient: srv.NewSOAPClient(),
-				RootDevice: maybeRootDevice.Root,
-				Service:    srv,
-			})
-		}
+		clients = append(clients, deviceClients...)
 	}
 
 	return
 }
 
+// NewServiceClientsByURL creates client(s) for the given service URN, for a
+// root device at the given URL.
+func NewServiceClientsByURL(loc *url.URL, searchTarget string) ([]ServiceClient, error) {
+	rootDevice, err := DeviceByURL(loc)
+	if err != nil {
+		return nil, err
+	}
+	return NewServiceClientsFromRootDevice(rootDevice, loc, searchTarget)
+}
+
+// NewServiceClientsFromDevice creates client(s) for the given service URN, for
+// a given root device. The location parameter is simply assigned to the
+// Location attribute of the returned ServiceClient.
+func NewServiceClientsFromRootDevice(rootDevice *RootDevice, location *url.URL, searchTarget string) ([]ServiceClient, error) {
+	device := &rootDevice.Device
+	srvs := device.FindService(searchTarget)
+	if len(srvs) == 0 {
+		return nil, fmt.Errorf("goupnp: service %q not found within device %q (UDN=%q)",
+			searchTarget, device.FriendlyName, device.UDN)
+	}
+
+	clients := make([]ServiceClient, 0, len(srvs))
+	for _, srv := range srvs {
+		clients = append(clients, ServiceClient{
+			SOAPClient: srv.NewSOAPClient(),
+			RootDevice: rootDevice,
+			Location:   location,
+			Service:    srv,
+		})
+	}
+	return clients, nil
+}
+
 // GetServiceClient returns the ServiceClient itself. This is provided so that the
 // service client attributes can be accessed via an interface method on a
 // wrapping type.