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+--- Thread: Output ZMQ-content to browser (/thread-6289.html)
Output ZMQ-content to browser - AarClay - Nov-14-2017
I have this code in Python. (Add i'm not a great python-expert ;) )
With this I can output the content of the ZeroMQ-stream to a file. Only writing to a file every 10 seconds does not seem to be really useful and costs a lot of performance.
Now I would like to show the content in a web-page. I am not an extreme python expert, but I have learned that I can set up a web server with PyBottle.
How can I integrate
PyBottle in my code, so it can output the latest message of the stream? I thought about the code of PyBottle in the **while**-loop.But do not I ( unnecessarily ) create a new web-server instance?
How can I handle this?
Or does anyone else have a good idea how to export the content of recent data from the stream to a browser?
Sample of
PyBottle: from bottle import route, run, template
@route( '/hello/<name>' )
def index( name ):
return template( '<b>Hello {{name}}</b>!', name = name )
run( host = 'localhost', port = 8080 )And my Python script, so far: #!/usr/bin/env python2
from gzip import GzipFile
from cStringIO import StringIO
from subprocess import call
pass; import zmq
context = zmq.Context()
subscriber = context.socket( zmq.XSUB )
subscriber.connect( "tcp://pubsub.*******.nl:7664" )
subscriber.send( chr( 0x01 ) # { 0x01: ZMQ_XSUB.subscribe,
+ "/RIG/VehiclePositions" # 0x00: ZMQ_XSUB.unsubscribe
) # }
while True:
multipart = subscriber.recv_multipart()
address = multipart[0]
contents = ''.join(multipart[1:])
contents = GzipFile( '', 'r', 0, StringIO( contents ) ).read()
filename = "tmp/treinpos.txt"
file = open( filename, "w" )
file.write( contents )
file.close()
subscriber.close()
context.term()
RE: Output ZMQ-content to browser - AarClay - Nov-15-2017
Anyone an idea how i can output the content to the browser?
RE: Output ZMQ-content to browser - snippsat - Nov-15-2017
I guess you mean Bottle and not PyBottle.
Quote:But do not I ( unnecessarily ) create a new web-server instance?Yes it's not good and unnecessarily to create a web-server instance for every update.
There are soultion for this and i would recommend Flask,
that has better support for stuff like this like Flask-SocketIO and jQuery + socket.io on the client side.
Also mention Celery that work well with Flask.
The topic of running background live update/stream tasks is complex.
If new to Python and web-develoment dos not help
Can show a solution that call a Python function on server side every 10-sec.
This is using Ajax to no reload browser,and done with jQuery on client side.
To help keep it clean
$.ajaxSetup({ cache: false });Will prevent all future AJAX requests from being cached.
setTimeout( will execute a script only one time) is better setInterval().
app.py:
from flask import Flask, render_template, jsonify, request
import random
app = Flask(__name__)
@app.route("/")
def test_job():
return render_template('index.html')
@app.route('/stuff', methods=['GET'])
def stuff():
'''Here stuff to be send to browser'''
val_random = random.random()
return jsonify(val_random=val_random)
if __name__ == "__main__":
app.run(debug=True)index.html:<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<link rel=stylesheet type=text/css href="{{ url_for('static', filename='css/style.css') }}" />
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<title>Show updated random number</title>
</head>
<body>
<div class="table">
<p id="rand_value">Value</p>
<button>Push to start random update</button>
</div>
</body>
<script>
$.ajaxSetup({ cache: false });
$(document).ready(function () {
$("button").click(function update_values() {
$.getJSON('/stuff', function (dat) {
$("#rand_value").text(dat['val_random']);
});
var interval = setTimeout(update_values, 10000);
});
});
</script>
</html>
RE: Output ZMQ-content to browser - AarClay - Nov-16-2017
Thank you for your extensive response. I will look at it from the weekend.
I am talking about the latest update in the stream, which must be shown in the browser.
How you can have this refreshed real-time by users, that is indeed with AJAX.
I was familiar with that point.
RE: Output ZMQ-content to browser - AarClay - Nov-24-2017
I do not understand at all?
This is what i must do first in my code, and of course make sure that flask is installed and running.
app = Flask(__name__)And so I have to put this code in the while loop?
@app.route("/")
def index():
return contentIs this right?
RE: Output ZMQ-content to browser - snippsat - Nov-24-2017
(Nov-24-2017, 02:26 PM)AarClay Wrote: And so I have to put this code in the while loop?No i think you are confused
Is this right?
There no while loop,the build web-server of Flask is what should be running.
Here is the full setup,also added Bootstrap to make button and random numbers text look better.
pip install FlaskFolder setup:
rand_numbers\ |-- app.py templates\ |-- index.htmlapp.py:
from flask import Flask, render_template, jsonify, request
import random
app = Flask(__name__)
@app.route("/")
def test_job():
return render_template('index.html')
@app.route('/stuff', methods=['GET'])
def stuff():
'''Here stuff to be send to browser'''
val_random = random.random()
return jsonify(val_random=val_random)
if __name__ == "__main__":
app.run(debug=True)index.html:<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<link rel=stylesheet type=text/css href="{{ url_for('static', filename='css/style4.css') }}" />
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet" >
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<title>Show updated random number</title>
</head>
<body style="background-color: rgb(186, 209, 231)">
<div class="text-center" role="group" aria-label="...">
<h1 class="text-success" id='numbers'>000000</h1>
<a id='b1' class="btn btn-primary"><span class="glyphicon glyphicon-random"></span> Random numbers</a>
</div>
</body>
<script>
$.ajaxSetup({ cache: false });
$(document).ready(function () {
$("#b1").click(function update_values() {
$.getJSON('/stuff', function (dat) {
$("#numbers").text(dat['val_random']);
});
var interval = setTimeout(update_values, 10000);
});
});
</script>
</html>No shall start web-server bye running python app.py in rand_numbers folder(always to this from command line).This will give you a address
http://127.0.0.1:5000/.This address do you copy and paste into browser,and push button to start random update every 10-sec.
RE: Output ZMQ-content to browser - AarClay - Nov-26-2017
But, i want to output the last message from the ZeroMQ stream. Not a random number....
Read my first post ;)
How can i integrate this, on the way that i describe?
RE: Output ZMQ-content to browser - snippsat - Nov-26-2017
(Nov-26-2017, 12:01 AM)AarClay Wrote: Read my first post ;)They point is not at all that i shall write everything for for you
ow can i integrate this, on the way that i describe?
Look at jsonify(),it can handle both python list and dict which will be JSON serialization automatic over the connection.
So when i do
jsonify(val_random=val_random) it will send this Response JSON object in browser {"val_random: 0.55719943207732"}.You have to look at your
contents,and think of how it can be transferred based on this info.
RE: Output ZMQ-content to browser - AarClay - Nov-26-2017
The content is also a JSON-string. I will try something.... Thanks :)
RE: Output ZMQ-content to browser - YogiMike - Jun-02-2021
thanks for the post snippsat. I used your example (with data changes) to use flask on my Raspberry Pi 2 with a Sense Hat to have a dynamic webpage which automatically updates Humidity, Temp, Barometric Pressure, and other data. It worked marvelously!!