Resolve "Implement missing functionality of subscription management"

Description

Related Issue

Motivation and Context

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

Related to #385

controller/northbound/server/submanagement.go

@@ -6,6 +6,8 @@ import (
 
 	subpb "code.fbi.h-da.de/danet/gosdn/api/go/gosdn/subscriptionmanagement"
 	"code.fbi.h-da.de/danet/gosdn/controller/nucleus"
+	"code.fbi.h-da.de/danet/gosdn/forks/goarista/gnmi"
+	"github.com/google/uuid"
 )
 
 // SubManagementServer represents a SubsriptionManagementServer.
@@ -67,3 +69,99 @@ func (s *SubManagementServer) GetAll(ctx context.Context, request *subpb.GetAllR
 		Subscriptions: subInfosToReturn,
 	}, nil
 }
+
+// Get fetches detailed info for one specific available subscription.
+func (s *SubManagementServer) Get(ctx context.Context, request *subpb.GetRequest) (*subpb.GetResponse, error) {
+	subUUID, err := uuid.Parse(request.GetSubid())
+	if err != nil {
+		return &subpb.GetResponse{
+			Timestamp: time.Now().UnixNano(),
+		}, err
+	}
+
+	info, err := s.networkElementWatchter.GetSubscriptionInformations(subUUID)
+	if err != nil {
+		return &subpb.GetResponse{
+			Timestamp: time.Now().UnixNano(),
+		}, err
+	}
+
+	var pathsToReturn []*subpb.Path
+	for _, path := range info.Opts.Paths {
+		var elems []string
+		for _, elem := range path {
+			elems = append(elems, elem)
+		}
+
+		pathsToReturn = append(pathsToReturn, &subpb.Path{Elem: elems})
+	}
+
+	return &subpb.GetResponse{
+		Timestamp: time.Now().UnixNano(),
+		Subscriptions: &subpb.Subscription{
+			Subid:   info.SubID,
+			Pid:     info.PndID,
+			Mneid:   info.MneID,
+			MneName: info.MneName,
+			Paths:   pathsToReturn,
+			SubscribeOptions: &subpb.SubscribeOptions{
+				GnmiMode:       info.Opts.Mode,
+				GnmiStreamMode: info.Opts.StreamMode,
+				SampleInterval: info.Opts.SampleInterval,
+			},
+		},
+	}, nil
+}
+
+// Delete stops and removes one specific running subscription is a no-op if object connected to ID does not exist.
+func (s *SubManagementServer) Delete(ctx context.Context, request *subpb.DeleteRequest) (*subpb.DeleteResponse, error) {
+	subUUID, err := uuid.Parse(request.GetSubid())
+	if err != nil {
+		return &subpb.DeleteResponse{
+			Timestamp: time.Now().UnixNano(),
+		}, err
+	}
+
+	s.networkElementWatchter.StopAndRemoveNetworkElementSubscription(subUUID)
+
+	return &subpb.DeleteResponse{
+		Timestamp: time.Now().UnixNano(),
+	}, nil
+}
+
+// Add creates a new subscription for the network element matching the provided ID using the provided subscribe options.
+func (s *SubManagementServer) Add(ctx context.Context, request *subpb.AddRequest) (*subpb.AddResponse, error) {
+	mneID, err := uuid.Parse(request.GetMneid())
+	if err != nil {
+		return &subpb.AddResponse{
+			Timestamp: time.Now().UnixNano(),
+		}, err
+	}
+
+	var paths [][]string
+	for _, path := range request.Subscription.Paths {
+		var elems []string
+		for _, elem := range path.Elem {
+			elems = append(elems, elem)
+		}
+		paths = append(paths, elems)
+	}
+
+	err = s.networkElementWatchter.SubscribeToNetworkElementWithID(mneID,
+		&gnmi.SubscribeOptions{
+			Mode:           request.Subscription.SubscribeOptions.GnmiMode,
+			StreamMode:     request.Subscription.SubscribeOptions.GnmiStreamMode,
+			SampleInterval: request.Subscription.SubscribeOptions.SampleInterval,
+			Paths:          paths,
+		},
+	)
+	if err != nil {
+		return &subpb.AddResponse{
+			Timestamp: time.Now().UnixNano(),
+		}, err
+	}
+
+	return &subpb.AddResponse{
+		Timestamp: time.Now().UnixNano(),
+	}, nil
+}