We have a wireless device (WIFI enabled) that calls a PHP script to enter data into MySQL db. Am trying to find a way to see if the server (through PHP script) can "connect" to the client device (has a microcontroller but doesn't have an OS or display) and pass some data.
The client is a electronic board connected to a gate and the server needs to tell the device to open the gate. Seems to be pretty straight forward but am new to this.
If the client is configured to listen on a specific port, you can open a socket connection to it from the server (using fsockopen()).
You'll need to configure the client though, which I have no idea how to do because your client is nothing standard.
Related
There are two socket servers that have to send messages to each other. The first one is a node.js server with socket.io. The second is ja php websocket (ratchet - http://socketo.me/).
The second server (ratchet) runs in a php application (created with a php framework like laravel or symfony) that contains a basic chat application.
The node.js server is like a global manager that can convey messages to multiple socket servers.
The communication ways are planned as follows:
Scenario a)
-> client / browser sends a message via websocket
-> php app receives message from browser by ratchet socket and stores this message in database
-> php sends / forwards message to node.js via socket
-> php sends response to client / browser via websocket
Scenario b)
-> node.js server sends a message to all connected php clients via socket
-> php receives message from node.js and stores this message in database
-> php sends this message to one or more connected browser clients
-> browser receives messages from php via websocket
What is the best way to enable this communication way? The browser is already able to talk to the ratchet server. But I have no idea how the ratchet server can talk to the node.js server an act as a normal socket client so that they will establish and hold a connection to each other. Is there a command to send a “hello, I am a new client that wants to establish a connection” message to the node.js server or vice versa?
Is this a good concept at all? Or is there a better way to send socket messages over multiple instances? Are there any tips, tutorials or examples? Other questions to this topic are very old or contains a different setup.
I'd probably use this : https://github.com/ratchetphp/Pawl to have PHP sending messages to nodejs.
Then about the concept being good, I think not.
There is no point in having two differents websockets servers imo.
I'd probably use only one websockets server (nodeJS), and have PHP and node "talk" together through a messaging queue like rabbitMQ / REDIS
Currently I'm working on a project is about chat system between client and agent by using socket.js and PHP.
Recently, received confirmation from client is client server will have load balancer to balance to different server.
Like picture below.
I'm found out an issue from this setup.
Agent A is connected to Server B, but Client A is connected to Server A, so Client A can't communicate with Agent A.
How can I solve this problem by using programming way?
PS:
Client is not allow me to edit any server config file or settings.
Client server is linux server.
Thanks for help :)
we have a similar problem. Right now we have a solution, but it is most likely not the best. When we start our 2 socket servers on 2 different servers, then each server also creates a socketconnection to the other socket server. So each socket server is also a client of the other socket server. When Socket Server A receives a communication it sends it to all connected users AND it also broadcasts it to Socket Server B, and that one sends it then to all connected users again.
Another solution is a Publish/Subscribe broker, like you can find in that link here https://hackernoon.com/scaling-websockets-9a31497af051.
Hope that helps somehow.
I am thinking about a scenario where I want to send a data packet from my php service (based on certain behaviour) to a client (can be Android or Windows) connected to it.
A device which is connected to the internet is going to have an ip address.
So is it possible to send a packet (using socket or else) to this ip directly (without polling from client end) and can this data be read from the client.
Scenario is like this :
Client A --------------Registers Own IP Address-----------------> Server
Client B --------------Registers Own IP Address-----------------> Server
Events :
Some changes occur in the database (say)
Server detects the affected client (via some algo),say Client A
Sends a packet to Client A
Client A <--------------Send Data Packet----------------- Server
Is this at-all possible ?
If yes, how effective can this be ?
Please note that, Push notifications is not applicable in my situation.
I am looking for a live (realtime) data transmission system between client and server (both ways).
Any suggestion, help will be useful. Thanx
Absolutely possible to have persistent sockets open.
but I would say this would fail in a hosted environment. GoDaddy etc shuts that down. Been there done that.
I would highly recommend choosing a programming language like java (Whatever you are comfortable with). It is only going to be 200 lines of code.
I want to control a robot from the web, the robot is connected to Android device. The operation will be as the following :
a web application written using JavaScript and HTML runs on desktop computer which takes the keyboard input from the user and send them to the android device connected to the robot.
the android device receive the commands and then send them to Arduino board which used to control the robot.
But how should I deliver the data to the Android device which doesn't has a static IP address?
I have two approaches to solve that :
the JavaScript application sends the keyboard input to a web server runs PHP and MySQL , then the php application store the data on the MySQL database. An application runs on Android connected to that web server and extract the data from the MySQL database.
the JavaScript sends the data to the web server. The android application connected to the web server receives the data directly so the web server is just used as a relay.
The first approach is easy to do but its slow , so my question is...
How to implement the second approach and which web technologies should I use to implement it? And how to make the web server works as relay between two sides?
PS : I am planning to use 000webhost.com as web server. so I will not use my own server
You can either have your Android application poll the webserver for outstanding commands. This is a little inefficient in terms of data usage, but if you're on an unlimited 3G plan / wi-fi, you could live with it. It will be very easy to implement.
Alternatively, set up a TCP server on your server, and have your Android application open a socket connection with the server. This way, your web application can send commands to the server which will immediately stream them to the Android device. It will be slightly harder to implement, but will be more efficient and robust if done right.
PS - Most shared servers don't allow you to open a TCP server on your host so you might be forced to go with the first option.
PPS - I wasn't aware of Google Cloud Messaging. It seems to be a good solution for you what you're attempting to achieve. You should have a look into it.
I have recently written a socket server in PHP that will be handling communication between an Android phone application and my PHP webserver. Due to the fact that Android doesn't natively support push style notifications we are going to be using our webserver as the middleware layer to handle our 'pushes'.
The socket server is stable, runs well, and seems to scale nicely. While I would eventually like to re-write this in C I don't have the skill necessary to do that right now so I am going to be staying in PHP for at least a short while. As of this moment our Android emulator is able to communicate through the server, get pushes, etc. so that part is all covered.
My concern is that, right now, anyone can open a socket to my server and will be given a client connection. While we won't be passing sensitive data back and forth I don't want to allow just anyone to connect over and receive broadcast information, eat up my resources, and clog my server in general.
The question is, how do I secure a server like this? Let's assume that I am running on port 25,000--can I set up some sort of SSL layer on that port and expect devices like the Android to be able to communicate over that port without any special protocols or jumping through hoops?
I have considered asking the connecting clients to authenticate their user against our user database before being given a client connection, but that would require the passing of credentials in plain text over the network which I am NOT about to do.
Any suggestions on this would be very helpful--I am rather new to straight TCP communication from PHP and feel like I might just be missing something simple that allows for authentication on this level.
Additional information: If I am able to get a valid username and password securely I would be using MySQL to validate the user and then accept/reject their connection based on the results of the query.
Thanks in advance..
First, I hope you've implemented your PHP socket server in a fashion that allows more than one client to be connected at the same time. This is not as trivial as it should be given the absence of threads in PHP, but it's certainly.
Now, if you already have a socket server implemented, adding TLS support is easy. Just run stunnel and have your PHP socket server only accept requests on the local interface.
I don't think SSL is really going to solve your problem. At best with SSL you can provide each client with a client certificate and do client certificate validation on the server. But you'll need to manage tons of certificates then. Or give everyone the same client certificate (not a good idea).
You'll have to authenticate the client using his credentials. You are right that you don't want to send the credentials in plain text over the network, but there are simple alternatives. Take a look at e.g. HTTP Digest Authentication (http://en.wikipedia.org/wiki/Digest_access_authentication) or xAuth (http://dev.twitter.com/pages/xauth). You don't have to implement these techniques over HTTP; you can just as well send a challenge (a realm) over a simple tcp socket after you have accepted the connection. The client should then send a valid response within a short timeframe or the server aborts the connection.
By the way, did you consider HTTP streaming? See http://ajaxpatterns.org/HTTP_Streaming
It would probably make your life a lot easier as you can rely upon some other service (e.g. Apache) doing the hard work for you, and you can focus on the business value of your application.
you might want to consider:
Cloud to Device Messaging : http://code.google.com/android/c2dm/index.html
The only drawback is that it is only supported by android >=2.2
Not sure why you guys didn't use some off the shelf messaging library/server for java, then create an android service that connects to the message broker and handles all initial authentication.
The service would simply sit there and wait for any incoming messages.
(I'm pretty sure that listening for network data doesn't power up the radio, only when the data is actually there that the radio powers up. I suspect this is how C2DM works.)
This is better then polling because you're only waiting for data. You're not constantly sending packets requesting data. But you knew that already.
I did this, (I used the rabbitmq-java library and the rabbitmq message queue server) and had push style notification for my app in no-time. Even with Android 1.5 devices.
About security:
You could also implement your own security but without having to send plain-text passwords. Simply encrypt the passwords using something like MD5 before passing it through the network.
Then compare the encrypted password with the encrypted password you have on file.
This way, only encrypted passwords will go through the network.