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subscriber.go
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/
subscriber.go
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//
// Copyright (C) 2021-2023 IOTech Ltd
//
// SPDX-License-Identifier: Apache-2.0
package messaging
import (
"context"
"encoding/json"
"fmt"
"net/url"
"strings"
"github.com/fxamacker/cbor/v2"
"github.com/edgexfoundry/edgex-go/internal/core/data/application"
dataContainer "github.com/edgexfoundry/edgex-go/internal/core/data/container"
"github.com/edgexfoundry/edgex-go/internal/pkg/utils"
"github.com/edgexfoundry/go-mod-messaging/v3/pkg/types"
"github.com/edgexfoundry/go-mod-bootstrap/v3/bootstrap/container"
"github.com/edgexfoundry/go-mod-bootstrap/v3/di"
"github.com/edgexfoundry/go-mod-core-contracts/v3/common"
"github.com/edgexfoundry/go-mod-core-contracts/v3/dtos"
"github.com/edgexfoundry/go-mod-core-contracts/v3/dtos/requests"
"github.com/edgexfoundry/go-mod-core-contracts/v3/errors"
)
// SubscribeEvents subscribes to events from message bus
func SubscribeEvents(ctx context.Context, dic *di.Container) errors.EdgeX {
messageBusInfo := dataContainer.ConfigurationFrom(dic.Get).MessageBus
lc := container.LoggingClientFrom(dic.Get)
messageBus := container.MessagingClientFrom(dic.Get)
messages := make(chan types.MessageEnvelope)
messageErrors := make(chan error)
app := application.CoreDataAppFrom(dic.Get)
subscribeTopic := common.BuildTopic(messageBusInfo.GetBaseTopicPrefix(), common.CoreDataEventSubscribeTopic)
topics := []types.TopicChannel{
{
Topic: subscribeTopic,
Messages: messages,
},
}
err := messageBus.Subscribe(topics, messageErrors)
if err != nil {
return errors.NewCommonEdgeXWrapper(err)
}
go func() {
for {
select {
case <-ctx.Done():
lc.Infof("Exiting waiting for MessageBus '%s' topic messages", subscribeTopic)
return
case e := <-messageErrors:
lc.Error(e.Error())
case msgEnvelope := <-messages:
lc.Debugf("Event received from MessageBus. Topic: %s, Correlation-id: %s", msgEnvelope.ReceivedTopic, msgEnvelope.CorrelationID)
event := &requests.AddEventRequest{}
// decoding the large payload may cause memory issues so checking before decoding
maxEventSize := dataContainer.ConfigurationFrom(dic.Get).MaxEventSize
edgeXerr := utils.CheckPayloadSize(msgEnvelope.Payload, maxEventSize*1024)
if edgeXerr != nil {
lc.Errorf("event size exceed MaxEventSize(%d KB)", maxEventSize)
break
}
err = unmarshalPayload(msgEnvelope, event)
if err != nil {
lc.Errorf("fail to unmarshal event, %v", err)
break
}
err = validateEvent(msgEnvelope.ReceivedTopic, event.Event)
if err != nil {
lc.Error(err.Error())
break
}
err = app.AddEvent(requests.AddEventReqToEventModel(*event), ctx, dic)
if err != nil {
lc.Errorf("fail to persist the event, %v", err)
}
}
}
}()
return nil
}
func unmarshalPayload(envelope types.MessageEnvelope, target interface{}) error {
var err error
switch envelope.ContentType {
case common.ContentTypeJSON:
err = json.Unmarshal(envelope.Payload, target)
case common.ContentTypeCBOR:
err = cbor.Unmarshal(envelope.Payload, target)
default:
err = fmt.Errorf("unsupported content-type '%s' recieved", envelope.ContentType)
}
return err
}
func validateEvent(messageTopic string, e dtos.Event) errors.EdgeX {
// Parse messageTopic by the pattern `edgex/events/device/<device-service-name>/<device-profile-name>/<device-name>/<source-name>`
fields := strings.Split(messageTopic, "/")
// assumes a non-empty base topic with events/device/<device-service-name>/<device-profile-name>/<device-name>/<source-name>
if len(fields) < 6 {
return errors.NewCommonEdgeX(errors.KindContractInvalid, fmt.Sprintf("invalid message topic %s", messageTopic), nil)
}
len := len(fields)
profileName, err := url.PathUnescape(fields[len-3])
if err != nil {
return errors.NewCommonEdgeXWrapper(err)
}
deviceName, err := url.PathUnescape(fields[len-2])
if err != nil {
return errors.NewCommonEdgeXWrapper(err)
}
sourceName, err := url.PathUnescape(fields[len-1])
if err != nil {
return errors.NewCommonEdgeXWrapper(err)
}
// Check whether the event fields match the message topic
if e.ProfileName != profileName {
return errors.NewCommonEdgeX(errors.KindContractInvalid, fmt.Sprintf("event's profileName %s mismatches with the name %s received in topic", e.ProfileName, profileName), nil)
}
if e.DeviceName != deviceName {
return errors.NewCommonEdgeX(errors.KindContractInvalid, fmt.Sprintf("event's deviceName %s mismatches with the name %s received in topic", e.DeviceName, deviceName), nil)
}
if e.SourceName != sourceName {
return errors.NewCommonEdgeX(errors.KindContractInvalid, fmt.Sprintf("event's sourceName %s mismatches with the name %s received in topic", e.SourceName, sourceName), nil)
}
return nil
}