// Module included in the following assemblies:
//
// * networking/ptp/ptp-cloud-events-consumer-dev-reference.adoc

:_mod-docs-content-type: REFERENCE
[id="ptp-events-consumer-application-{ptp-events-rest-api}_{context}"]
= PTP events consumer application reference

PTP event consumer applications require the following features:

. A web service running with a `POST` handler to receive the cloud native PTP events JSON payload
. A `createSubscription` function to subscribe to the PTP events producer
. A `getCurrentState` function to poll the current state of the PTP events producer

The following example Go snippets illustrate these requirements:

.Example PTP events consumer server function in Go
[source,go]
----
func server() {
  http.HandleFunc("/event", getEvent)
  http.ListenAndServe("localhost:8989", nil)
}

func getEvent(w http.ResponseWriter, req *http.Request) {
  defer req.Body.Close()
  bodyBytes, err := io.ReadAll(req.Body)
  if err != nil {
    log.Errorf("error reading event %v", err)
  }
  e := string(bodyBytes)
  if e != "" {
    processEvent(bodyBytes)
    log.Infof("received event %s", string(bodyBytes))
  } else {
    w.WriteHeader(http.StatusNoContent)
  }
}
----

.Example PTP events createSubscription function in Go
[source,go,subs="attributes+"]
----
import (
"github.com/redhat-cne/sdk-go/pkg/pubsub"
"github.com/redhat-cne/sdk-go/pkg/types"
v1pubsub "github.com/redhat-cne/sdk-go/v1/pubsub"
)

// Subscribe to PTP events using REST API
s1,_:=createsubscription("/cluster/node/<node_name>/sync/sync-status/os-clock-sync-state") <1>
s2,_:=createsubscription("/cluster/node/<node_name>/sync/ptp-status/class-change")
s3,_:=createsubscription("/cluster/node/<node_name>/sync/ptp-status/lock-state")

// Create PTP event subscriptions POST
func createSubscription(resourceAddress string) (sub pubsub.PubSub, err error) {
  var status int
      apiPath:= "/api/ocloudNotifications/{ptp-events-rest-api}/"
      localAPIAddr:=localhost:8989 // vDU service API address
      apiAddr:= "localhost:8089" // event framework API address

  subURL := &types.URI{URL: url.URL{Scheme: "http",
    Host: apiAddr
    Path: fmt.Sprintf("%s%s", apiPath, "subscriptions")}}
  endpointURL := &types.URI{URL: url.URL{Scheme: "http",
    Host: localAPIAddr,
    Path: "event"}}

  sub = v1pubsub.NewPubSub(endpointURL, resourceAddress)
  var subB []byte

  if subB, err = json.Marshal(&sub); err == nil {
    rc := restclient.New()
    if status, subB = rc.PostWithReturn(subURL, subB); status != http.StatusCreated {
      err = fmt.Errorf("error in subscription creation api at %s, returned status %d", subURL, status)
    } else {
      err = json.Unmarshal(subB, &sub)
    }
  } else {
    err = fmt.Errorf("failed to marshal subscription for %s", resourceAddress)
  }
  return
}
----
<1> Replace `<node_name>` with the FQDN of the node that is generating the PTP events. For example, `compute-1.example.com`.

.Example PTP events consumer getCurrentState function in Go
[source,go,subs="attributes+"]
----
//Get PTP event state for the resource
func getCurrentState(resource string) {
  //Create publisher
  url := &types.URI{URL: url.URL{Scheme: "http",
    Host: localhost:8989,
    Path: fmt.SPrintf("/api/ocloudNotifications/{ptp-events-rest-api}/%s/CurrentState",resource}}
  rc := restclient.New()
  status, event := rc.Get(url)
  if status != http.StatusOK {
    log.Errorf("CurrentState:error %d from url %s, %s", status, url.String(), event)
  } else {
    log.Debugf("Got CurrentState: %s ", event)
  }
}
----
