Add a cross-plank example (WIP)

plank/cmd/cross_plank_communication/server_one/config.json

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+{
+  "debug": false,
+  "no_banner": false,
+  "root_dir": "./",
+  "spa_config": {
+    "root_folder": "public/",
+    "base_uri": "/",
+    "static_assets": [
+      "public/assets:/assets"
+    ],
+    "cache_control_rules": {
+      "*.{js,css}": "public, max-age=86400",
+      "*.{ico,jpg,jpeg,svg,png,gif,tiff}": "public, max-age=604800"
+    }
+  },
+  "host": "localhost",
+  "port": 30081,
+  "log_config": {
+    "root": ".",
+    "access_log": "access.log",
+    "error_log": "errors.log",
+    "output_log": "stdout",
+    "format_options": {
+      "force_colors": false,
+      "disable_colors": true,
+      "force_quote": false,
+      "disable_quote": false,
+      "environment_override_colors": false,
+      "disable_timestamp": false,
+      "full_timestamp": true,
+      "timestamp_format": "",
+      "disable_sorting": false,
+      "disable_level_truncation": false,
+      "pad_level_text": false,
+      "quote_empty_fields": false,
+      "is_terminal": true
+    }
+  },
+  "shutdown_timeout_in_minutes": 1,
+  "rest_bridge_timeout_in_minutes": 1,
+  "fabric_config": {
+    "fabric_endpoint": "/ws",
+    "use_tcp": false,
+    "tcp_port": 61613,
+    "endpoint_config": {
+      "TopicPrefix": "/topic",
+      "UserQueuePrefix": "/queue",
+      "AppRequestPrefix": "/pub",
+      "AppRequestQueuePrefix": "/pub/queue",
+      "Heartbeat": 60000
+    }
+  },
+  "enable_prometheus": true
+}

plank/cmd/cross_plank_communication/server_one/server_one.go

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+// Copyright 2022 VMware, Inc.
+// SPDX-License-Identifier: BSD-2-Clause
+
+package main
+
+import (
+	"github.com/vmware/transport-go/plank/pkg/server"
+	"github.com/vmware/transport-go/plank/services"
+	"github.com/vmware/transport-go/plank/utils"
+	"os"
+)
+
+// configure flags
+func main() {
+	serverConfig, err := server.CreateServerConfig()
+	if err != nil {
+		utils.Log.Fatalln(err)
+	}
+	platformServer := server.NewPlatformServer(serverConfig)
+	if err = platformServer.RegisterService(services.NewPingPongService(), services.PingPongServiceChan); err != nil {
+		utils.Log.Fatalln(err)
+	}
+
+	syschan := make(chan os.Signal, 1)
+	platformServer.StartServer(syschan)
+}

plank/cmd/cross_plank_communication/server_two/config.json

@@ -0,0 +1,54 @@
+{
+  "debug": false,
+  "no_banner": false,
+  "root_dir": "./",
+  "spa_config": {
+    "root_folder": "public/",
+    "base_uri": "/",
+    "static_assets": [
+      "public/assets:/assets"
+    ],
+    "cache_control_rules": {
+      "*.{js,css}": "public, max-age=86400",
+      "*.{ico,jpg,jpeg,svg,png,gif,tiff}": "public, max-age=604800"
+    }
+  },
+  "host": "localhost",
+  "port": 30080,
+  "log_config": {
+    "root": ".",
+    "access_log": "access.log",
+    "error_log": "errors.log",
+    "output_log": "stdout",
+    "format_options": {
+      "force_colors": false,
+      "disable_colors": true,
+      "force_quote": false,
+      "disable_quote": false,
+      "environment_override_colors": false,
+      "disable_timestamp": false,
+      "full_timestamp": true,
+      "timestamp_format": "",
+      "disable_sorting": false,
+      "disable_level_truncation": false,
+      "pad_level_text": false,
+      "quote_empty_fields": false,
+      "is_terminal": true
+    }
+  },
+  "shutdown_timeout_in_minutes": 1,
+  "rest_bridge_timeout_in_minutes": 1,
+  "fabric_config": {
+    "fabric_endpoint": "/ws",
+    "use_tcp": false,
+    "tcp_port": 61613,
+    "endpoint_config": {
+      "TopicPrefix": "/topic",
+      "UserQueuePrefix": "/queue",
+      "AppRequestPrefix": "/pub",
+      "AppRequestQueuePrefix": "/pub/queue",
+      "Heartbeat": 60000
+    }
+  },
+  "enable_prometheus": true
+}

plank/cmd/cross_plank_communication/server_two/server_two.go

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+// Copyright 2022 VMware, Inc.
+// SPDX-License-Identifier: BSD-2-Clause
+
+package main
+
+import (
+	"github.com/vmware/transport-go/bridge"
+	"github.com/vmware/transport-go/bus"
+	"github.com/vmware/transport-go/plank/pkg/server"
+	"github.com/vmware/transport-go/plank/services"
+	"github.com/vmware/transport-go/plank/utils"
+	"os"
+	"time"
+)
+
+// configure flags
+func main() {
+	serverConfig, err := server.CreateServerConfig()
+	if err != nil {
+		utils.Log.Fatalln(err)
+	}
+	platformServer := server.NewPlatformServer(serverConfig)
+	brokerConfigForAnotherWs := &bridge.BrokerConnectorConfig{
+		Username:        "guest",
+		Password:        "guest",
+		ServerAddr:      "localhost:30081",
+		UseWS:           true,
+		WebSocketConfig: &bridge.WebSocketConfig{WSPath: "/ws"},
+		HeartBeatOut:    30 * time.Second,
+		STOMPHeader:     map[string]string{},
+	}
+	if err = platformServer.RegisterService(services.NewExternalBrokerExampleService(bus.GetBus(), brokerConfigForAnotherWs), services.ExternalBrokerExampleServiceChannel); err != nil {
+		utils.Log.Fatalln(err)
+	}
+
+	syschan := make(chan os.Signal, 1)
+	platformServer.StartServer(syschan)
+}

plank/services/cross_plank_example.go

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+package services
+
+import (
+	"encoding/json"
+	"github.com/google/uuid"
+	"github.com/vmware/transport-go/bridge"
+	"github.com/vmware/transport-go/bus"
+	"github.com/vmware/transport-go/model"
+	"github.com/vmware/transport-go/plank/utils"
+	"github.com/vmware/transport-go/service"
+	"sync"
+	"time"
+)
+
+const ExternalBrokerExampleServiceChannel = "external-broker-example-service"
+const localSyncBusChannel string = "ext-svc"
+
+type ExternalBrokerExampleService struct {
+	targetBroker *bridge.BrokerConnectorConfig
+	conn         bridge.Connection
+	bus          bus.EventBus
+	mu           sync.Mutex
+}
+
+func NewExternalBrokerExampleService(bus bus.EventBus, config *bridge.BrokerConnectorConfig) *ExternalBrokerExampleService {
+	service := &ExternalBrokerExampleService{
+		bus:          bus,
+		targetBroker: config,
+	}
+	return service
+}
+
+func (s *ExternalBrokerExampleService) HandleServiceRequest(request *model.Request, core service.FabricServiceCore) {
+	// in this example, I wrote it so that "ping" request assumes the broker session is established already, but in real
+	// scenarios you may wish to ensure the connection is alive and healthy. maybe you will want to create a few more
+	// service requests to handle the lifecycle of the WS connection to the other broker. for example, you could create
+	// a request "connect" for connecting to the external broker and "disconnect" for closing the connection explicitly.
+	switch request.Request {
+	case "ping":
+		// we create a single-fire listener for the channel that's linked to the other broker
+		handler, err := s.bus.ListenOnce(localSyncBusChannel)
+		if err != nil {
+			// failed to set up the listener. this rarely happens though but still it helps to make sure all errors are tracked.
+			core.SendErrorResponse(request, 500, err.Error())
+			return
+		}
+
+		// we will take the payload from the local request and use it to send a remote request in L67
+		utils.Log.Infoln("RECEIVED LOCAL REQUEST PAYLOAD", request.Payload)
+
+		// set up the handler for responses returned back from the external broker
+		handler.Handle(func(message *model.Message) {
+			var payload model.Response
+			if err := message.CastPayloadToType(&payload); err != nil {
+				utils.Log.Errorln("RECEIVED RESPONSE BUT FAILED TO CAST", err)
+				core.SendErrorResponse(request, 500, err.Error())
+			}
+			// pass back the success response from the external broker back to the requester.
+			core.SendResponse(request, payload.Payload)
+			utils.Log.Infof("RECEIVED RESPONSE: %v\n", payload.Payload)
+		}, func(err error) {
+			// external broker sent an error. pass it back to the requester.
+			core.SendErrorResponse(request, 400, err.Error())
+			utils.Log.Errorln("RECEIVED ERROR RESPONSE FROM EXTERNAL BROKER", err)
+			return
+		})
+
+		// create a request object for the remote service "ping-pong-service" with request named "ping-get" and pass it
+		// through the external broker using the connection we established when the service started. see ping-pong-service
+		// L60 for the data structure for the request payload that the service accepts
+		req := &model.Request{Request: "ping-get", Payload: request.Payload.(string)}
+		reqMarshalled, _ := json.Marshal(req)
+		if err = s.conn.SendJSONMessage("/pub/queue/ping-pong-service", reqMarshalled); err != nil {
+			core.SendErrorResponse(request, 400, err.Error())
+			return
+		}
+
+	default:
+		core.SendErrorResponse(request, 400, "unknown service")
+	}
+}
+
+func (s *ExternalBrokerExampleService) OnServiceReady() chan bool {
+	ready := make(chan bool, 1)
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	// connect to the external broker
+	var err error
+	if s.conn, err = s.bus.ConnectBroker(s.targetBroker); err != nil {
+		utils.Log.Errorln("[external-broker-example-service] could not connect to the broker. Service failed to start")
+		ready <- false
+		return ready
+	} else {
+		utils.Log.Infoln("[external-broker-example-service] connected to external broker!")
+
+		// create a local channel named "ext-svc" and bridge it to the external broker
+		busChannelManager := s.bus.GetChannelManager()
+		busChannelManager.CreateChannel(localSyncBusChannel)
+		if err = s.bus.GetChannelManager().MarkChannelAsGalactic(localSyncBusChannel, "/queue/ping-pong-service", s.conn); err != nil {
+			utils.Log.Errorln(err)
+			ready <- false
+			return ready
+		}
+	}
+
+	// this is just to demonstrate that a message travels from this Plank process to another.
+	// you can use any WebSocket client instead to send a request message to this service and get a response back.
+	go func() {
+		t := time.NewTicker(5 * time.Second)
+		<-t.C
+		_ = s.bus.SendRequestMessage(ExternalBrokerExampleServiceChannel, model.Request{Id: &uuid.UUID{}, Request: "ping", Payload: "HI!"}, nil)
+	}()
+
+	// at this point, a connection between this Plank and the other broker is established and the local channel "ext-svc"
+	// is synced to the bus channel "ping-pong-service" from the other Plank. set the service to ready and return the channel.
+	ready <- true
+	return ready
+}
+
+func (js *ExternalBrokerExampleService) GetRESTBridgeConfig() []*service.RESTBridgeConfig {
+	return nil
+}
+
+func (s *ExternalBrokerExampleService) OnServerShutdown() {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	// disconnect from bridge connection
+	if s.conn != nil {
+		utils.Log.Infoln("[external-broker-example-service] disconnecting from external broker")
+		if err := s.conn.Disconnect(); err != nil {
+			utils.Log.Errorln(err)
+		}
+	}
+}