This is more of a conceptual understanding gap rather than technical one. I am new to web socket\messaging api's.
I ran a chat application using faye ruby server and everything works fine between two browsers.I want to send a message from a stand alone ruby client to a browser client which is sending messages to same server. Is it possible to send a message from a client like the one below to a browser whose script is also given below ?
This is not related to the application I created, but I was trying to understand the use of WS client api. Or specifically put , can I send message from a server client to browser client ? I guess I am lacking the understanding of the word 'client' here.
I see the messages on the server console, but the browser doesn't get the message sent by the stand alone client.
Also I see this when i run the client :
Started GET "/faye/test123" for 127.0.0.1 at 2015-04-09 07:17:46 -0400
require 'faye'
require 'eventmachine'
EM.run {
ws = Faye::WebSocket::Client.new('ws://localhost:9292/faye/test123')
ws.onopen = lambda do |event|
p [:open, ws.headers]
ws.send('987654321')
end
ws.on :open do |event|
p [:open]
ws.send('123 123 123 123')
p [:sent]
end
}
Browser script :
window.client = new Faye.Client('http://localhost:9292/faye');
client.subscribe('/test123', function(payload){
if(payload.message)
{
console.log('I am in here 77777.......'+payload.message);
return $("#incomingText").append(payload.message);
}
}
Looking at your code I think it might be useful to highlight the difference between websockets and faye.
Faye is a framework that supports a number of transports, websockets being just one of them. It can also do long polling for example. One of the benefits of Faye is that it can select the right transport that both the client and server understand. It also implements a simple pub/sub protocol on top of that transport, giving you a nice API to build off of.
Doing a pure websocket implementation is totally doable, but if you're going to go with Faye it's probably a good idea to use Faye's publish/subscribe API and not muck with Faye's websockets directly.
To answer your specific question:
Is it possible to send a message from a client like the one below to a browser whose script is also given below ?
Yes, absolutely but I would suggest doing it with Faye::Client. Here's what your server side code might look like:
client = Faye::Client.new('http://localhost:9292/faye')
client.publish('/test123', 'message' => 'Hello world')
With much more info here:
http://faye.jcoglan.com/ruby/clients.html
Related
I have this Telegram bot written in Lua that I am doing as a hobby for a language network. And I have been reading new messages via the getUpdates API call all the time. Now I want to rewrite it to use webhooks, but I have no experience with that whatsoever. I have googled but didn't find anything certain. I kinda feel that WSAPI is the library to use, but I am not sure. Moreover, I am not really sure I need any special library just for reading POST requests (which is all that the Telegram bot API uses). I tried using sockets:
socket = require 'socket'
server = assert(socket.bind("*", 9000))
function read(client, pattern, prefix)
local data, emsg, partial = client:receive(pattern, prefix)
if data then
return data
end
if partial and #partial > 0 then
return partial
end
return nil, emsg
end
while true do
local client = server:accept()
client:settimeout(3)
local msg, err = read(client, '*a')
if not err then
print(msg)
client:close()
end
end
The print(msg) here gives me the full POST request including headers, which I am probably able to parse (the body is supposed to always be a JSON). I am not really that familiar with HTTP requests though and I'm not sure I can just throw away everything that goes before the first {.
My setup is Lua 5.2, Ubuntu x64 16.04 and Nginx. What I need to do is to receive and read POST requests, nothing more.
TL;DR: is it okay to parse the POST request I receive from the code above or am I missing something, like a library that'd make my life easier?
Thanks!
I'm trying to upload to my server (on Heroku) a file stored in a password protected FTP.
The problem is that this FTP also dont contain my production IP address on his whitelist (and i cant add it..) so i should use a proxy to connect my rails app this FTP.
I tried this code :
proxy_uri = URI(ENV['QUOTAGUARDSTATIC_URL'] || 'http://login:password#myproxy.com:9293')
Net::HTTP::Proxy(proxy_uri.host, proxy_uri.port,"login","password").start('ftp://login:password#ftp.website.com') do |http|
http.get('/path/to/myfile.gz').body
end
But my http.get returns me lookup ftp: no such host.
I also got this code for FTP download, but i dont know how to make it works with a proxy :
ftp = Net::FTP.new('ftp.myftp.com', 'login', 'password')
ftp.chdir('path/to')
ftp.getbinaryfile('myfile.gz', 'public/myfile.gz', 1024)
ftp.close
Thanks in advance.
I realise that you asked this question over 6 months ago, but I recently had a similar issue and found that this (unanswered) question is the top Google result, so I thought I would share my findings.
mudasobwa's comment below your original post has a link to the net/ftp documentation which explains how to use a SOCKS proxy...
Although you don't mention a specific requirement for a HTTP proxy in your original post, it seems obvious to me that is what you were trying to use. As I'm sure you're aware, this makes the SOCKS documentation totally irrelevant.
The following code has been tested on ruby-1.8.7-p357 using an HTTP proxy that does not require authentication:
file = File.open('myfile.gz', 'w')
http = Net::HTTP.start('myproxy.com', '9293')
resp, data = http.get('ftp://login:password#ftp.website.com')
file.write(data) if resp.code == "200"
file.close unless file.nil?
Source
This should give you a good starting point to figure the rest out for yourself.
To get you going, I would guess that you could use user:pass#myproxy.com for basic auth, or perhaps sending a Proxy-Authorization header in your GET request.
For reasons similar to the ones in this discussion, I'm experimenting with messaging in lieu of REST for a synchronous RPC call from one Rails 3 application to another. Both apps are running on thin.
The "server" application has a config/initializers/amqp.rb file based on the Request / Reply pattern in the rubyamqp.info documentation:
require "amqp"
EventMachine.next_tick do
connection = AMQP.connect ENV['CLOUDAMQP_URL'] || 'amqp://guest:guest#localhost'
channel = AMQP::Channel.new(connection)
requests_queue = channel.queue("amqpgem.examples.services.time", :exclusive => true, :auto_delete => true)
requests_queue.subscribe(:ack => true) do |metadata, payload|
puts "[requests] Got a request #{metadata.message_id}. Sending a reply..."
channel.default_exchange.publish(Time.now.to_s,
:routing_key => metadata.reply_to,
:correlation_id => metadata.message_id,
:mandatory => true)
metadata.ack
end
Signal.trap("INT") { connection.close { EventMachine.stop } }
end
In the 'client' application, I'd like to render the results of a synchronous call to the 'server' in a view. I realize this is a bit outside the comfort zone of an inherently asynchronous library like the amqp gem, but I'm wondering if there's a way to make it work. Here is my client config/initializers/amqp.rb:
require 'amqp'
EventMachine.next_tick do
AMQP.connection = AMQP.connect 'amqp://guest:guest#localhost'
Signal.trap("INT") { AMQP.connection.close { EventMachine.stop } }
end
Here is the controller:
require "amqp"
class WelcomeController < ApplicationController
def index
puts "[request] Sending a request..."
WelcomeController.channel.default_exchange.publish("get.time",
:routing_key => "amqpgem.examples.services.time",
:message_id => Kernel.rand(10101010).to_s,
:reply_to => WelcomeController.replies_queue.name)
WelcomeController.replies_queue.subscribe do |metadata, payload|
puts "[response] Response for #{metadata.correlation_id}: #{payload.inspect}"
#message = payload.inspect
end
end
def self.channel
#channel ||= AMQP::Channel.new(AMQP.connection)
end
def self.replies_queue
#replies_queue ||= channel.queue("reply", :exclusive => true, :auto_delete => true)
end
end
When I start both applications on different ports and visit the welcome#index view.
#message is nil in the view, since the result has not yet returned. The result arrives a few milliseconds after the view is rendered and is displayed on the console:
$ thin start
>> Using rack adapter
>> Thin web server (v1.5.0 codename Knife)
>> Maximum connections set to 1024
>> Listening on 0.0.0.0:3000, CTRL+C to stop
[request] Sending a request...
[response] Response for 3877031: "2012-11-27 22:04:28 -0600"
No surprise here: subscribe is clearly not meant for synchronous calls. What is surprising is that I can't find a synchronous alternative in the AMQP gem source code or in any documentation online. Is there an alternative to subscribe that will give me the RPC behavior I want? Given that there are other parts of the system in which I'd want to use legitimately asynchronous calls, the bunny gem didn't seem like the right tool for the job. Should I give it another look?
edit in response to Sam Stokes
Thanks to Sam for the pointer to throw :async / async.callback. I hadn't seen this technique before and this is exactly the kind of thing I was trying to learn with this experiment in the first place. send_response.finish is gone in Rails 3, but I was able to get his example to work for at least one request with a minor change:
render :text => #message
rendered_response = response.prepare!
Subsequent requests fail with !! Unexpected error while processing request: deadlock; recursive locking. This may have been what Sam was getting at with the comment about getting ActionController to allow concurrent requests, but the cited gist only works for Rails 2. Adding config.allow_concurrency = true in development.rb gets rid of this error in Rails 3, but leads to This queue already has default consumer. from AMQP.
I think this yak is sufficiently shaven. ;-)
While interesting, this is clearly overkill for simple RPC. Something like this Sinatra streaming example seems a more appropriate use case for client interaction with replies. Tenderlove also has a blog post about an upcoming way to stream events in Rails 4 that could work with AMQP.
As Sam points out in his discussion of the HTTP alternative, REST / HTTP makes perfect sense for the RPC portion of my system that involves two Rails apps. There are other parts of the system involving more classic asynchronous event publishing to Clojure apps. For these, the Rails app need only publish events in fire-and-forget fashion, so AMQP will work fine there using my original code without the reply queue.
You can get the behaviour you want - have the client make a simple HTTP request, to which your web app responds asynchronously - but you need more tricks. You need to use Thin's support for asynchronous responses:
require "amqp"
class WelcomeController < ApplicationController
def index
puts "[request] Sending a request..."
WelcomeController.channel.default_exchange.publish("get.time",
:routing_key => "amqpgem.examples.services.time",
:message_id => Kernel.rand(10101010).to_s,
:reply_to => WelcomeController.replies_queue.name)
WelcomeController.replies_queue.subscribe do |metadata, payload|
puts "[response] Response for #{metadata.correlation_id}: #{payload.inspect}"
#message = payload.inspect
# Trigger Rails response rendering now we have the message.
# Tested in Rails 2.3; may or may not work in Rails 3.x.
rendered_response = send_response.finish
# Pass the response to Thin and make it complete the request.
# env['async.callback'] expects a Rack-style response triple:
# [status, headers, body]
request.env['async.callback'].call(rendered_response)
end
# This unwinds the call stack, skipping the normal Rails response
# rendering, all the way back up to Thin, which catches it and
# interprets as "I'll give you the response later by calling
# env['async.callback']".
throw :async
end
def self.channel
#channel ||= AMQP::Channel.new(AMQP.connection)
end
def self.replies_queue
#replies_queue ||= channel.queue("reply", :exclusive => true, :auto_delete => true)
end
end
As far as the client is concerned, the result is indistinguishable from your web app blocking on a synchronous call before returning the response; but now your web app can process many such requests concurrently.
CAUTION!
Async Rails is an advanced technique; you need to know what you're doing. Some parts of Rails do not take kindly to having their call stack abruptly dismantled. The throw will bypass any Rack middlewares that don't know to catch and rethrow it (here is a rather old partial solution). ActiveSupport's development-mode class reloading will reload your app's classes after the throw, without waiting for the response, which can cause very confusing breakage if your callback refers to a class that has since been reloaded. You'll also need to ask ActionController nicely to allow concurrent requests.
Request/response
You're also going to need to match up requests and responses. As it stands, if Request 1 arrives, and then Request 2 arrives before Request 1 gets a response, then it's undefined which request would receive Response 1 (messages on a queue are distributed round-robin between the consumers subscribed to the queue).
You could do this by inspecting the correlation_id (which you'll have to explicitly set, by the way - RabbitMQ won't do it for you!) and re-enqueuing the message if it's not the response you were waiting for. My approach was to create a persistent Publisher object which would keep track of open requests, listen for all responses, and lookup the appropriate callback to invoke based on the correlation_id.
Alternative: just use HTTP
You're really solving two different (and tricky!) problems here: persuading Rails/thin to process requests asynchronously, and implementing request-response semantics on top of AMQP's publish-subscribe model. Given you said this is for calling between two Rails apps, why not just use HTTP, which already has the request-response semantics you need? That way you only have to solve the first problem. You can still get concurrent request processing if you use a non-blocking HTTP client library, such as em-http-request.
I'm currently hosting both my rails app and a faye-server app on Heroku. The faye server has been cloned from here (https://github.com/ntenisOT/Faye-Heroku-Cedar) and seems to be running correctly. I have disabled websockets, as they are not supported on Heroku. Despite the claim on Faye's site that:
"Faye clients and servers transparently support cross-domain communication, so your client can connect to a server on any domain you like without further configuration."
I am still running into this error when I try to post to a faye channel:
XMLHttpRequest cannot load http://MYFAYESERVER.herokuapp.com. Origin http://MYAPPURL.herokuapp.com is not allowed by Access-Control-Allow-Origin.
I have read about CORS and tried implementing some solutions outlined here: http://www.tsheffler.com/blog/?p=428 but have so far had no luck. I'd love to hear from someone who:
1) Has a rails app hosted on Heroku
2) Has a faye server hosted on Heroku
3) Has the two of them successfully communicating with each other!
Thanks so much.
I just got my faye and rails apps hosted on heroku communicating within the past hour or so... here are my observations:
Make sure your FAYE_TOKEN is set on all of your servers if you're using an env variable.
Disable websockets, which you've already done... client.disable(...) didn't work for me, I used Faye.Transport.WebSocket.isUsable = function(_,c) { c(false) } instead.
This may or may not apply to you, but was the hardest thing to track down for me... in my dev environment, the port my application is running on will be tacked onto the end of the specified hostname for my faye server... but this appeared to cause a failure to communicate in production. I worked around that by creating a broadcast_server_uri method in application_controller.rb that handles inclusion of a port when necessary, and then use that anywhere I spin up a new channel.
....
class ApplicationController < ActionController::Base
def broadcast_server
if request.port.to_i != 80
"http://my-faye-server.herokuapp.com:80/faye"
else
"http://my-faye-server.herokuapp.com/faye"
end
end
helper_method :broadcast_server
def broadcast_message(channel, data)
message = { :ext => {:auth_token => FAYE_TOKEN}, :channel => channel, :data => data}
uri = URI.parse(broadcast_server)
Net::HTTP.post_form(uri, :message => message.to_json)
end
end
And in my app javascript, including
<script>
var broadcast_server = "<%= broadcast_server %>"
var faye;
$(function() {
faye = new Faye.Client(broadcast_server);
faye.setHeader('Access-Control-Allow-Origin', '*');
faye.connect();
Faye.Transport.WebSocket.isUsable = function(_,c) { c(false) }
// spin off your subscriptions here
});
</script>
FWIW, I wouldn't stress about setting Access-Control-Allow-Origin as it doesn't seem to be making a difference either way - I see XMLHttpRequest cannot load http://... regardless, but this should still works well enough to get you unblocked. (although I'd love to learn of a cleaner solution...)
Can't say I have used Rails/Faye on Heroku but have you tried setting the Access-Control-Allow-Origin header to something like Access-Control-Allow-Origin: your-domain.com?
For testing you could also do Access-Control-Allow-Origin: * to see if that helps
Custom headers
Some services require the use of additional HTTP headers to connect to
their Bayeux server. You can add these headers using the setHeader()
method, and they will be sent if the underlying transport supports
user-defined headers (currently long-polling only).
client.setHeader('Authorization', 'OAuth abcd-1234');
Source: http://faye.jcoglan.com/browser.html
So try client.setHeader('Access-Control-Allow-Origin', '*');
I have a Rails project and two ruby mini-daemons running in the background. What's the best way to communicate between them?
Communication like below should be possible:
Rails -> Process 1 -> Process 2 -> Rails
Some requests would be sync, other async.
Queues (something like AMQ, or custom Redis based) or RPC HTTP calls?
Check DRb as well.
I implemented a system via RabbitMq + the bunny gem.
Update:
After reading http://blog.brightbox.co.uk/posts/queues-and-callbacks I decided to try out RabbitMQ. There are two gems amqp (async, eventmachine based) or bunny (sync). amqp is great, but if you're using Rails with passenger it can do some weird things.
The system works like this, the daemons listen on a queue for messages:
# The incoming data should be a JSON encoded hash that looks like:
# { "method" => method_to_call, "opts" => [ Array of opts for method ],
# "output" => "a queue where to send the result (optional)" }
# If output is specified it will publish the JSON encoded response there.
def listen_on(queue_name, class)
BUNNY.start
bunny = BUNNY.queue(queue_name)
bunny.subscribe do |msg|
msg = JSON.parse(msg[:payload])
result = class.new.send(msg["method"], *msg["opts"])
if msg["output"]
BUNNY.queue(msg["output"]).publish(result.to_json)
end
end
So once a message is received it calls a method from a class. One thing to note is that it would have been ideal to use bunny for Rails and amqp in the daemons. But I like to use one gem pe service.