[lbry] rpc: add a blocknotify example using lbcd websocket

rpcclient/examples/lbcdblocknotify/README.md

@@ -0,0 +1,34 @@
+lbcd Websockets Example
+=======================
+
+This example shows how to use the rpcclient package to connect to a btcd RPC
+server using TLS-secured websockets, register for block connected and block
+disconnected notifications, and get the current block count.
+
+## Running the Example
+
+The first step is to use `go get` to download and install the rpcclient package:
+
+```bash
+$ go get github.com/lbryio/lbcd/rpcclient
+```
+
+Next, modify the `main.go` source to specify the correct RPC username and
+password for the RPC server:
+
+```Go
+	User: "yourrpcuser",
+	Pass: "yourrpcpass",
+```
+
+Finally, navigate to the example's directory and run it with:
+
+```bash
+$ git clone github.com/lbryio/lbcd
+$ cd rpcclient/examples/lbcdblocknotify
+$ go run .
+```
+
+## License
+
+This example is licensed under the [copyfree](http://copyfree.org) ISC License.

rpcclient/examples/lbcdblocknotify/main.go

@@ -0,0 +1,67 @@
+// Copyright (c) 2014-2017 The btcsuite developers
+// Use of this source code is governed by an ISC
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"io/ioutil"
+	"log"
+	"path/filepath"
+
+	"github.com/lbryio/lbcd/rpcclient"
+	"github.com/lbryio/lbcd/wire"
+	"github.com/lbryio/lbcutil"
+)
+
+func main() {
+	// Only override the handlers for notifications you care about.
+	// Also note most of these handlers will only be called if you register
+	// for notifications.  See the documentation of the rpcclient
+	// NotificationHandlers type for more details about each handler.
+	ntfnHandlers := rpcclient.NotificationHandlers{
+		OnFilteredBlockConnected: func(height int32, header *wire.BlockHeader, txns []*lbcutil.Tx) {
+			log.Printf("Block connected: %v (%d) %v",
+				header.BlockHash(), height, header.Timestamp)
+		},
+		OnFilteredBlockDisconnected: func(height int32, header *wire.BlockHeader) {
+			log.Printf("Block disconnected: %v (%d) %v",
+				header.BlockHash(), height, header.Timestamp)
+		},
+	}
+
+	// Connect to local lbcd RPC server using websockets.
+	lbcdHomeDir := lbcutil.AppDataDir("lbcd", false)
+	certs, err := ioutil.ReadFile(filepath.Join(lbcdHomeDir, "rpc.cert"))
+	if err != nil {
+		log.Fatal(err)
+	}
+	connCfg := &rpcclient.ConnConfig{
+		Host:         "localhost:9245",
+		Endpoint:     "ws",
+		User:         "rpcuser",
+		Pass:         "rpcpass",
+		Certificates: certs,
+	}
+	client, err := rpcclient.New(connCfg, &ntfnHandlers)
+	if err != nil {
+		log.Fatalln(err)
+	}
+
+	// Register for block connect and disconnect notifications.
+	if err := client.NotifyBlocks(); err != nil {
+		log.Fatalln(err)
+	}
+	log.Println("NotifyBlocks: Registration Complete")
+
+	// Get the current block count.
+	blockCount, err := client.GetBlockCount()
+	if err != nil {
+		log.Fatal(err)
+	}
+	log.Printf("Block count: %d", blockCount)
+
+	// Wait until the client either shuts down gracefully (or the user
+	// terminates the process with Ctrl+C).
+	client.WaitForShutdown()
+}