I'm trying to figure out how can I call a grpc server from a javascript function in my nodejs application, and update my page... I don't know how can I manage it.
This is the proto file:
syntax = "proto3";
package helloworld;
service Greeter {
rpc SayHello (HelloRequest) returns (HelloReply) {}
}
message HelloRequest {
string name = 1;
}
message HelloReply {
string message = 1;
}
this is the server:
var PROTO_PATH = __dirname + '/helloworld.proto';
var grpc = require('grpc');
var hello_proto = grpc.load(PROTO_PATH).helloworld;
function sayHello(call, callback) {
callback(null, {message: 'Hello ' + call.request.name});
}
function main() {
var server = new grpc.Server();
server.addProtoService(hello_proto.Greeter.service, {sayHello: sayHello});
server.bind('0.0.0.0:50051', grpc.ServerCredentials.createInsecure());
server.start();
}
main();
this is the javascript function :
var PROTO_PATH = __dirname + '/helloworld.proto';
var grpc = require('grpc');
var hello_proto = grpc.load(PROTO_PATH).helloworld;
function test() {
var client = new hello_proto.Greeter('localhost:50051',
grpc.credentials.createInsecure());
client.sayHello(function(err, response) {
console.log('Greeting:', response.message);
document.getElementById("para").innerHTML = 'Mex Received from grpc server ' + response.message;
});
}
when I click a button on my page i call the function test and i would like to update the element(id=para).
Any idea?
Related
Im trying to send an answer to my websocket-server from a component which does not contain the websocket. My Websocket server looks like this:
componentDidMount() {
var ws = new WebSocket('ws:// URL');
ws.onmessage = this.handleMessage.bind(this);
...
}
How can I pass the "var ws" to another class or component. Or is it possible to make the websocket globally accessable?
Thank you very much for any help!
I found a solution with help from this question in stackoverflow:
visit:
React native: Always running component
I created a new class WebsocketController like this:
let instance = null;
class WebsocketController{
constructor() {
if(!instance){
instance = this;
}
this.ws = new WebSocket('ws://URL');
return instance;
}
}
export default WebsocketController
And then in my other class where I need my websocket I just called it like this:
let controller = new WebsocketController();
var ws = controller.ws;
websocket connection
keep this code in some file, name it with .js extenstion. ex: websocket.js
var WebSocketServer = require("ws").Server;
var wss = new WebSocketServer({port:8100});
wss.broadcast = function broadcast(msg) {
console.log(msg);
wss.clients.forEach(function each(client) {
client.send(msg);
});
};
wss.on('connection', function connection(ws) {
// Store the remote systems IP address as "remoteIp".
var remoteIp = ws.upgradeReq.connection.remoteAddress;
// Print a log with the IP of the client that connected.
console.log('Connection received: ', remoteIp);
ws.send('You successfully connected to the websocket.');
ws.on('message',wss.broadcast);
});
In your app/website side. create .js file. Ex: client.js
var SERVER_URL = 'ws://127.0.0.1:8100';
var ws;
function connect() {
//alert('connect');
ws = new WebSocket(SERVER_URL, []);
// Set the function to be called when a message is received.
ws.onmessage = handleMessageReceived;
// Set the function to be called when we have connected to the server.
ws.onopen = handleConnected;
// Set the function to be called when an error occurs.
ws.onerror = handleError;
}
function handleMessageReceived(data) {
// Simply call logMessage(), passing the received data.
logMessage(data.data);
}
function handleConnected(data) {
// Create a log message which explains what has happened and includes
// the url we have connected too.
var logMsg = 'Connected to server: ' + data.target.url;
// Add the message to the log.
logMessage(logMsg)
ws.send("hi am raj");
}
function handleError(err) {
// Print the error to the console so we can debug it.
console.log("Error: ", err);
}
function logMessage(msg) {
// $apply() ensures that the elements on the page are updated
// with the new message.
$scope.$apply(function() {
//Append out new message to our message log. The \n means new line.
$scope.messageLog = $scope.messageLog + msg + "\n";
});
}
Please let me know if you face any issue with this code
I am trying to develop a publish/subscribe application where a Java program is a publisher and nodejs program is a subscriber. The Java client connects to MQTT server and sends some random data. The NodeJS client should subscribe to the topic the java client has registered. I am getting the data from java client on to the NodeJS console, but I have to print that data asynchronously on a web page.
Here's the code I've written.
MqttPublishSample.java
public class MqttPublishSample {
public static void main(String[] args) {
String topic = "MQTT-Examples";
String content = "HelloWorld";
int qos = 2;
int i =0;
String broker = "tcp://localhost:1883";
String clientId = "JavaSample";
MemoryPersistence persistence = new MemoryPersistence();
try {
MqttClient sampleClient = new MqttClient(broker, clientId, persistence);
MqttConnectOptions connOpts = new MqttConnectOptions();
connOpts.setCleanSession(true);
System.out.println("Connecting to broker: " + broker);
sampleClient.connect(connOpts);
System.out.println("Connected");
while(i < 100)
{
int num = (int) (Math.random() * 2);
String text = content + num;
System.out.println("Publishing message: "+content+ " "+ num);
MqttMessage message = new MqttMessage(text.getBytes());
message.setQos(qos);
sampleClient.publish(topic, message);
System.out.println("Message published");
i++;
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
// System.out.println("Publishing message: " + content);
/*sampleClient.disconnect();
System.out.println("Disconnected");
System.exit(0);*/
} catch (MqttException me) {
System.out.println("reason " + me.getReasonCode());
System.out.println("msg " + me.getMessage());
System.out.println("loc " + me.getLocalizedMessage());
System.out.println("cause " + me.getCause());
System.out.println("excep " + me);
me.printStackTrace();
}
}
}
app.js
var express = require('express');
var app = express();
app.get('/', function (req, res) {
client.on('connect', function() {
console.log("Connection Successful");
client.subscribe('MQTT-Examples');
});
var content;
client.on('message', function (topic, message) {
content = message;
console.log(message.toString());
});
res.render('index', { title: content });
});
app.listen(3000, function () {
console.log('Example app listening on port 3000!');
});
I tried printing the message on the web page but I am unable to see any message.
I need to asynchronously print the data on the web page. Any help with how to proceed. Thanks!
try moving the line res.render('index', { title: content }); inside the callback for client.on e.g:
var express = require('express');
var app = express();
/*
* MQTT Client
*/
var content = ""; //buffer
client.on('connect', function() {
console.log("Connection Successful");
client.subscribe('MQTT-Examples');
});
client.on('message', function(topic, message) {
content += message.toString() + "<br>";
console.log(message.toString());
});
/*
* Express
*/
app.get('/', function(req, res) {
res.render('index', {
title: content
});
});
app.listen(3000, function() {
console.log('Example app listening on port 3000!');
});
Update
I did update to code, in the new code you will be able to see all messages received every time you reload the web page.
In the previous implementation was a kind of long polling, the resource will wait for a message from the broker.
Hope it helps.
So I want to be able to share methods across different node.js processes created using the cluster module.
If I run the code below I can share the method server.handleRequest across the child processes, however If I uncomment //server.test(); in the second file and try to use the method test in the original process, node crashes.
"use strict";
var os = require('os');
var http = require('http');
var cluster = require('cluster');
function testMethod() {
console.log('Test');
}
function handleRequest(req, res) {
res.writeHead(200);
res.end("This answer comes from the process " + process.pid);
}
var createServer = function createServer(opts) {
var server = {};
server.test = testMethod;
server.handleRequest = handleRequest;
if (cluster.isMaster) {
var cpuCount = require('os').cpus().length;
for (var i = 0; i < cpuCount; i += 1) {
cluster.fork();
}
return server;
} else {
// Create HTTP server.
http.Server(function(req, res) {
server.handleRequest(req, res);
}).listen(8080);
}
}
module.exports = {
createServer: createServer,
};
The second file that includes the above file.
"use strict";
var router = require('./test.js');
var server = router.createServer();
//server.test();
But If I don't use the cluster module I can use the test method outside the factory function with out crashing. So how do I share methods created in factory functions across all node processes, while using the cluster module? And why do the child processes execute test when only the original process calls server.test()?
var http = require('http');
function testMethod() {
console.log('Test');
}
function handleRequest(req, res) {
res.writeHead(200);
res.end("This answer comes from the process " + process.pid);
}
var createServer = function createServer(opts) {
var server = {};
server.test = testMethod;
server.handleRequest = handleRequest;
http.Server(function(req, res) {
server.handleRequest(req, res);
}).listen(8080);
return server;
}
module.exports = {
createServer: createServer,
};
I am trying to install protractor in my Mac. The installation is done via command line but one of the scripts is failing due to connectivity problems. The main problem is that I am behind a corporate proxy server.
I set the proxy server in my console and npm is also configured with the correct proxy settings.
The script that fails is here
and it contains the following
#!/usr/bin/env node
var fs = require('fs');
var os = require('os');
var url = require('url');
var http = require('http');
var AdmZip = require('adm-zip')
// Download the Selenium Standalone jar and the ChromeDriver binary to
// ./selenium/
// Thanks to http://www.hacksparrow.com/using-node-js-to-download-files.html
// for the outline of this code.
var SELENIUM_URL =
'http://selenium.googlecode.com/files/selenium-server-standalone-2.35.0.jar';
var CHROMEDRIVER_URL_MAC =
'https://chromedriver.googlecode.com/files/chromedriver_mac32_2.2.zip';
var CHROMEDRIVER_URL_LINUX32 =
'https://chromedriver.googlecode.com/files/chromedriver_linux32_2.2.zip';
var CHROMEDRIVER_URL_LINUX64 =
'https://chromedriver.googlecode.com/files/chromedriver_linux64_2.2.zip';
var CHROMEDRIVER_URL_WINDOWS =
'https://chromedriver.googlecode.com/files/chromedriver_win32_2.2.zip';
var DOWNLOAD_DIR = './selenium/';
var START_SCRIPT_FILENAME = DOWNLOAD_DIR + 'start';
var chromedriver_url = '';
var start_script = 'java -jar selenium/selenium-server-standalone-2.35.0.jar';
if (!fs.existsSync(DOWNLOAD_DIR) || !fs.statSync(DOWNLOAD_DIR).isDirectory()) {
fs.mkdirSync(DOWNLOAD_DIR);
}
console.log(
'When finished, start the Selenium Standalone Server with ./selenium/start \n');
// Function to download file using HTTP.get
var download_file_httpget = function(file_url, callback) {
console.log('downloading ' + file_url + '...');
var options = {
host: url.parse(file_url).host,
port: 80,
path: url.parse(file_url).pathname
};
var file_name = url.parse(file_url).pathname.split('/').pop();
var file_path = DOWNLOAD_DIR + file_name;
var file = fs.createWriteStream(file_path);
http.get(options, function(res) {
res.on('data', function(data) {
file.write(data);
}).on('end', function() {
file.end(function() {
console.log(file_name + ' downloaded to ' + file_path);
if (callback) {
callback(file_path);
}
});
});
});
};
download_file_httpget(SELENIUM_URL);
if (!(process.argv[2] == '--nocd')) {
if (os.type() == 'Darwin') {
chromedriver_url = CHROMEDRIVER_URL_MAC;
} else if (os.type() == 'Linux') {
if (os.arch() == 'x64') {
chromedriver_url = CHROMEDRIVER_URL_LINUX64;
} else {
chromedriver_url = CHROMEDRIVER_URL_LINUX32;
}
} else if (os.type() == 'Windows_NT') {
chromedriver_url = CHROMEDRIVER_URL_WINDOWS;
}
var chromedriver_zip = chromedriver_url.split('/').pop();
start_script += ' -Dwebdriver.chrome.driver=./selenium/chromedriver';
download_file_httpget(chromedriver_url, function(file_name) {
var zip = new AdmZip(file_name);
zip.extractAllTo(DOWNLOAD_DIR);
if (os.type() != 'Windows_NT') {
fs.chmod(DOWNLOAD_DIR + 'chromedriver', 0755);
}
});
}
var start_script_file = fs.createWriteStream(START_SCRIPT_FILENAME);
start_script_file.write(start_script);
start_script_file.end(function() {
fs.chmod(START_SCRIPT_FILENAME, 0755);
});
How can we modify this script in order to resolve the connectivity issue?
In download_file_httpget, you're calling http.get(...). That makes a direct connection to the target server.
Configuring a proxy in npm only affects npm. Node's http module has no concept of proxy servers.
If you need to make a request through a proxy, consider using the request module, which does support proxies.
I have a basic Node JS server which is designed to be used as an API, I've created a log and database module and I've started adding other modules to deal with different request types.
I'm using Express.js and node-mysql
When I visit /v1/group I get the following error -
TypeError: Cannot read property 'database' of undefined
at Group.getAll (C:\code\javascript\node\api\api\v1\groups.js:12:23)
at callbacks (C:\code\javascript\node\api\node_modules\express\lib\router\index.js:161:37) ...
So I guess after recieving a request and calling group.getAll() that this is undefined but I don't understand why, is there a way to set this or have I structured my application all wrong?
sever.js
"use strict";
var Express = require('express');
var Log = require('./database/log');
var Database = require('./database/database');
var dbConfig = require('./dbconfig.json');
var Group = require('./api/v1/groups');
//Init express
var app = new Express();
//Init log and database
var log = new Log();
var database = new Database(dbConfig, log);
var initCallback = function() {
//Init routes
var group = new Group(database, log);
//Group routes
app.get('/v1/group', group.getAll);
app.get('/v1/group/:id', group.getByID);
app.listen(3000);
log.logMessage("INFO", "Listening on port 3000");
};
//Test database connection
database.getConnection(function(err, connection) {
if (err) {
log.logMessage("FATAL", "Error connecting to database, check database is running and the dbconfig.json file is present and correct.");
process.exit(1);
}
connection.end();
initCallback();
});
database.js
"use strict";
var mysql = require('mysql');
var Database = function(dbConfig, log) {
this.connected = false;
this.log = log;
this.log.logMessage("INFO", "Connecting to database with: Host - " + dbConfig.dbhost + ", Database port - " + dbConfig.dbport + ", Database name - " + dbConfig.dbname + ", User " + dbConfig.dbuser + ", Password length - " + dbConfig.dbpass.length);
this.pool = mysql.createPool({
host : dbConfig.dbhost,
user : dbConfig.dbuser,
port: dbConfig.dbport,
password : dbConfig.dbpass,
database: dbConfig.dbname
});
};
Database.prototype.getConnection = function() {
var args = arguments;
return this.pool.getConnection.apply(this.pool, arguments);
};
module.exports = Database;
groups.js
"use strict";
var Group = function(database, log) {
this.database = database;
this.log = log;
};
Group.prototype.getAll = function(req, res) {
console.log(this); // --> undefined
var query = 'SELECT * FROM invgroups WHERE published = 1';
this.database.getConnection(function(err, connection) { // --> error line
if (err) { res.send(500, "Database error"); }
connection.query(query, function(err, results) {
if (err) { res.send(500, "Database error"); }
res.send(results);
});
connection.end();
});
};
Group.prototype.getByID = function(req, res) {
console.log(this);
res.send({name: "Group Item 1"});
};
module.exports = Group;
You need to properly bind the function.
app.get('/v1/group', group.getAll);
only passes the getAll function as a handler, but the function itself has no concept of this. this is decided based on the context that is bound, or based on how the function is called. This blog post is useful for understanding how function context works.
app.get('/v1/group', group.getAll.bind(group));