I am trying to connect a sensor to an AWS MQTT Broker to a database that will send it to a webserver so that it can be easily accessible. Right now the only way people in our lab can have access to our sensor data is through contacting me directly and having me connect to the Node Red dashboard. Would there be any way for everyone to have access to the data via WebSocket, or at least a couple of people?
I've searched for hours on end and have had no success regarding the ease of accessibility.
From what I've researched there is this a java based client called MQTT.Cool that can connect multiple brokers and have data published via WebSocket using JavaScript. However there is literally no data available except the ones provided by the company. So combining it it with my project has not been an easy task.
Also, I've thought about allowing my node red dashboard to be accessed out of my local
ip-address, but due to security reasons it has been recommended not to be done.
AWS IoT provides an SDK that you can use in your browser:
https://github.com/aws/aws-iot-device-sdk-js#browser
You can write a web application and view the contents returned by the database after logging in
If you need to browse in real-time, you can use mqtt.js to subscribe to some topics：
https://www.emqx.com/en/blog/connect-to-mqtt-broker-with-websocket
Or use MQTTX, a client tool, to connect directly to the MQTT broker and subscribe to topic
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I receive continuously data by uart sérial port.
How can i print this data on my html web site and update it dynamically ?
I use a raspberry pi 3 with apache server.
I can use php, javascript, python... and many languages.
You could create a NodeJS server, with express for example.
Then use the serialport npm module to get data from your serial port.
Then send this data through a websocket, create a web page, and use the Websocket Javascript API to retrieve the data from your websocket.
This way, you can display real-time data from serial port on your website. I've used this 'stack' to build a connected aquaponics system in a Hackathon and it worked well !
It would even be simplier if you use socket.io, since it provides simple library and code example for both the back-end and the front-end part.
Hope it helps,
Best regards
How to send database data to pubnub and how to receive data from pubnub website for live data streaming
Its not clearly.
Not sure what the actual question is here but I'll attempt to address it.
PubNub is not really a website, it's a realtime network service with serverless Functions that can process the messages that are published through that network.
You send data to the PubNub using the publish or fire API. You receive data using the subscribe API. You just need to pick a PubNub SDK (there's over 70 to choose from) to implement your app using these APIs. Here's the JavaScript SDK for example. Put Functions aside for now and concentrate on the publish/subscribe part first.
Also, you might want to review How PubNub Works docs to understand what PubNub is (and is not) and what it can do for your applications you use it in.
I am working on a home automation hub -- a Raspberry Pi running locally that displays weather info, controls my lights, etc. It is "networked" (and I use that term loosely) to a website via a shared MongoDB. Both the site and the hub are running Node.js/Express servers.
Essentially, I am looking to be able to enter text into a field on my website and then display it on my hub.
I'm struggling to figure out how to pass data between them. I can think of a couple ways that might get it done, but the only way I know I could get working is to implement some sort of Mongo watcher/listener to watch for changes on a specific collection. Essentially, you enter the text into the site, that updates the document in Mongo, the watcher informs the locally-running hub, which then fetches and displays the new content.
This seems hacky. Is there a better way? Is this something socket.io could manage? Maybe I'm overthinking it? Help!
You can use Socket.io, WebSocket or TCP socket to connect the two servers together and communicate that way. Or you can use a queue system like ZeroMQ or RabbitMQ and communicate that way. Or you can even make an HTTP request from one server to the other one every time you want it to grab new data - or you could even sent that data right in the request.
It would be much easier if you used Redis that supports pub/sub, see:
https://redis.io/topics/pubsub
or CouchDB that supports the changes feed:
http://docs.couchdb.org/en/2.0.0/api/database/changes.html
or RethinkDB that supports changefeeds:
https://rethinkdb.com/docs/changefeeds/javascript/
I don't think Mongo supports anything like that.
What I want to achieve:
I have a linux server connected to network which runs a database. The database is not reachable from network. There is a software which acts as a middle layer between the server and client(s). The clients would access the database through this layer. This is required because:
There will be multiple users with different permissions.
I want a common API because the client software will be implemented to mobile platform, mostly for Android and as a webpage(this is where I want to use JavaScript) as well.
I don't want to expose the database directly to clients because I would be forced to store the database's login credentials in client's device.
The client software will be used only for data exchange and displaying the result to user. Any processing would be done in server.
The part which is not clear is the webpage. I could use PHP, but I want to make it like the Google Hangouts app in Gmail or the Facebook Messenger. The content which is fetched from database is displayed without reloading the page. Since I have't done anything like this in JavaScript, I don't know where to start, which libraries I should use.
Note that the communication between the client and the server would be done over secure sockets. The middle layer would be implemented in C++ using OpenSSL.
I would suggest to connect to the server using C++ with the system() command.
Weather javascript is a database enabled language?
Can javascript be used as a language to connect and query the database? If yes why and if no why? Please explain in detail?
Theoretically any programming language can be used to connect to a database, as long as it has the proper db libraries that the developer can use to connect to the DBMS.
In particularly javascript has some limitations (like servers it can connect to, resources from PC that can access), when run inside a web browser container, limitations that are not part of the language itself. Node.js on the other hand doesn't have these limitations.
Most of the times you'll need a proxy between your javascript ajax calls and the actual database, because:
on one hand to not publicly expose the db credentials and also as secured databases don't allow remote connections,
and on the other hand as many DBMS require a binary communication protocol, which is not feasible to be implemented in javascript (there are DBMS which allow a json-based communication though)
My recommendation: implement the DB connect and query logic on the server-side part, and build a (RESTful) API to indirectly access the database this way. This also gives you control over what a logged in user can do with the database.