client/watch.go

// Licensed to the Apache Software Foundation (ASF) under one or more
// contributor license agreements.  See the NOTICE file distributed with
// this work for additional information regarding copyright ownership.
// The ASF licenses this file to You under the Apache License, Version 2.0
// (the "License"); you may not use this file except in compliance with
// the License.  You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package client

import (
	"context"
	"encoding/json"
	"fmt"
	"log"

	pb "github.com/apache/servicecomb-service-center/pkg/registry"
	scerr "github.com/apache/servicecomb-service-center/server/scerror"
	"github.com/gorilla/websocket"
)

const (
	apiWatcherURL = "/v4/%s/registry/microservices/%s/watcher"
)

func (c *Client) Watch(ctx context.Context, domain, project, selfServiceID string, callback func(*pb.WatchInstanceResponse)) *scerr.Error {
	headers := c.CommonHeaders(ctx)
	headers.Set("X-Domain-Name", domain)

	conn, err := c.WebsocketDial(ctx, fmt.Sprintf(apiWatcherURL, project, selfServiceID), headers)
	if err != nil {
		return scerr.NewError(scerr.ErrInternal, err.Error())
	}

	for {
		messageType, message, err := conn.ReadMessage()
		if err != nil {
			log.Println(err)
			break
		}
		if messageType == websocket.TextMessage {
			data := &pb.WatchInstanceResponse{}
			err := json.Unmarshal(message, data)
			if err != nil {
				log.Println(err)
				break
			}
			callback(data)
		}
	}
	return scerr.NewError(scerr.ErrInternal, err.Error())
}