Add support for methods

This patch adds support for the Method Service Set to call methods on
the server.

Fixes #251

.gitignore

@@ -1,2 +1,3 @@
 vendor/
 dist/
+__pycache__/

README.md

@@ -125,7 +125,7 @@ The current set of supported services is only for the high-level client.
 |                             | Write                         | Yes       |              |
 |                             | HistoryRead                   | Yes       |              |
 |                             | HistoryUpdate                 |           |              |
-| Method Service Set          | Call                          |           |              |
+| Method Service Set          | Call                          | Yes       |              |
 | MonitoredItems Service Set  | CreateMonitoredItems          | Yes       |              |
 |                             | DeleteMonitoredItems          | Yes       |              |
 |                             | ModifyMonitoredItems          |           |              |

client.go

@@ -516,6 +516,24 @@ func (c *Client) Browse(req *ua.BrowseRequest) (*ua.BrowseResponse, error) {
 	return res, err
 }
 
+// Call executes a synchronous call request for a single method.
+func (c *Client) Call(req *ua.CallMethodRequest) (*ua.CallMethodResult, error) {
+	creq := &ua.CallRequest{
+		MethodsToCall: []*ua.CallMethodRequest{req},
+	}
+	var res *ua.CallResponse
+	err := c.Send(creq, func(v interface{}) error {
+		return safeAssign(v, &res)
+	})
+	if err != nil {
+		return nil, err
+	}
+	if len(res.Results) != 1 {
+		return nil, ua.StatusBadUnknownResponse
+	}
+	return res.Results[0], nil
+}
+
 // Subscribe creates a Subscription with given parameters. Parameters that have not been set
 // (have zero values) are overwritten with default values.
 // See opcua.DefaultSubscription* constants

examples/method/method.go

@@ -0,0 +1,49 @@
+// Copyright 2018-2019 opcua authors. All rights reserved.
+// Use of this source code is governed by a MIT-style license that can be
+// found in the LICENSE file.
+
+package main
+
+import (
+	"context"
+	"flag"
+	"log"
+
+	"github.com/gopcua/opcua"
+	"github.com/gopcua/opcua/debug"
+	"github.com/gopcua/opcua/ua"
+)
+
+func main() {
+	var (
+		endpoint = flag.String("endpoint", "opc.tcp://localhost:4840", "OPC UA Endpoint URL")
+	)
+	flag.BoolVar(&debug.Enable, "debug", false, "enable debug logging")
+	flag.Parse()
+	log.SetFlags(0)
+
+	ctx := context.Background()
+
+	c := opcua.NewClient(*endpoint, opcua.SecurityMode(ua.MessageSecurityModeNone))
+	if err := c.Connect(ctx); err != nil {
+		log.Fatal(err)
+	}
+	defer c.Close()
+
+	in := int64(12)
+	req := &ua.CallMethodRequest{
+		ObjectID:       ua.NewStringNodeID(2, "main"),
+		MethodID:       ua.NewStringNodeID(2, "even"),
+		InputArguments: []*ua.Variant{ua.MustVariant(in)},
+	}
+
+	resp, err := c.Call(req)
+	if err != nil {
+		log.Fatal(err)
+	}
+	if got, want := resp.StatusCode, ua.StatusOK; got != want {
+		log.Fatalf("got status %v want %v", got, want)
+	}
+	out := resp.OutputArguments[0].Value()
+	log.Printf("%d is even: %v", in, out)
+}

uatest/method_server.py

@@ -0,0 +1,25 @@
+#!/usr/bin/env python3
+
+from opcua import ua, Server
+
+def even(parent, variant):
+    print("even method call with parameters: ", variant.Value)
+    ret = (variant.Value % 2 == 0)
+    print("even", type(ret))
+    return [ua.Variant(ret, ua.VariantType.Boolean)]
+
+def square(parent, variant):
+    print("square method call with parameters: ", variant.Value)
+    variant.Value *= variant.Value
+    return [variant]
+
+if __name__ == "__main__":
+    server = Server()
+    server.set_endpoint("opc.tcp://0.0.0.0:4840/")
+
+    ns = server.register_namespace("http://gopcua.com/")
+    main = server.nodes.objects.add_object(ua.NodeId("main", ns), "main")
+    fnEven = main.add_method(ua.NodeId("even", ns), "even", even, [ua.VariantType.Int64], [ua.VariantType.Boolean])
+    fnSquare = main.add_method(ua.NodeId("square", ns), "square", square, [ua.VariantType.Int64], [ua.VariantType.Int64])
+
+    server.start()

uatest/method_test.go

@@ -0,0 +1,54 @@
+// +build integration
+
+package uatest
+
+import (
+	"context"
+	"testing"
+
+	"github.com/gopcua/opcua"
+	"github.com/gopcua/opcua/ua"
+	"github.com/pascaldekloe/goe/verify"
+)
+
+func TestCallMethod(t *testing.T) {
+	tests := []struct {
+		req *ua.CallMethodRequest
+		out []*ua.Variant
+	}{
+		{
+			req: &ua.CallMethodRequest{
+				ObjectID: ua.NewStringNodeID(2, "main"),
+				MethodID: ua.NewStringNodeID(2, "even"),
+				InputArguments: []*ua.Variant{
+					ua.MustVariant(int64(12)),
+				},
+			},
+			out: []*ua.Variant{ua.MustVariant(true)},
+		},
+	}
+
+	srv := NewServer("method_server.py")
+	defer srv.Close()
+
+	c := opcua.NewClient(srv.Endpoint, srv.Opts...)
+	if err := c.Connect(context.Background()); err != nil {
+		t.Fatal(err)
+	}
+	defer c.Close()
+
+	for _, tt := range tests {
+		t.Run(tt.req.ObjectID.String(), func(t *testing.T) {
+			resp, err := c.Call(tt.req)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if got, want := resp.StatusCode, ua.StatusOK; got != want {
+				t.Fatalf("got status %v want %v", got, want)
+			}
+			if got, want := resp.OutputArguments, tt.out; !verify.Values(t, "", got, want) {
+				t.Fail()
+			}
+		})
+	}
+}

uatest/rw_server.py

@@ -1,18 +1,12 @@
 #!/usr/bin/env python3
 
-import logging
 from opcua import ua, Server
 
 if __name__ == "__main__":
-    logging.basicConfig(level=logging.WARN)
-
     server = Server()
-    server.set_endpoint("opc.tcp://0.0.0.0:4840/gopcua/server/")
-    server.set_server_name("OPC/UA server Read/Write tests")
-
-    uri = "http://gopcua.com/"
-    ns = server.register_namespace(uri)
+    server.set_endpoint("opc.tcp://0.0.0.0:4840/")
 
+    ns = server.register_namespace("http://gopcua.com/")
     main = server.nodes.objects.add_object(ua.NodeId("main", ns), "main")
     roBool = main.add_variable(ua.NodeId("ro_bool", ns), "ro_bool", True, ua.VariantType.Boolean)
     rwBool = main.add_variable(ua.NodeId("rw_bool", ns), "rw_bool", True, ua.VariantType.Boolean)