I know how to make communication in client -> service direction, but I need communication in direction service -> client. I would need some observer on client or some way that I can call client from server.
Marko
I think you can use Client Notifications for that. Check the client notification how-to page for a raw description of what you need to add to your application.
I never used them myself. Be aware that they are not a solution for all use cases.
Related
I'm working on a PoC of a system where a mobile app client needs to be connected on a server with communications going both ways : either for updating the server or being updated by it. There is no client-to-client communications for the moment.
The client logs in the server via an HTTPS/POST method and gets back a token if the credentials are OK. This token is to be used by any further communication in order to authenticate the user. The reason why I'm using HTTPS for logging in is that there also is a web interface for other purposes.
I could not find a tutorial or documentation that explains how to implement this use case with channels based on websocket transport. All I found so far are either partial and focus on some specific aspects (eg authentication, setting SSL/TLS, etc) and assume the reader already knows the rest or are the over simplified implementations of the chat app. I'm sure I'm not looking at the right place...
My questions are:
What would be the list of callback to implement this use case on
either side
On the server: how does a process send notifications to the
client
NB: I'm using Elixir 1.5.1 and Phoenix 1.3
From the Phoenix guide:
Each Channel will implement one or more clauses of each of these four callback functions — join/3, terminate/2, handle_in/3, and handle_out/3.
The page I linked contains also an MCVE of sockets running on Phoenix. In the bottom there are examples of how the server-client communication is done.
The only thing to apply this to your use-case would be to use one of authentication libraries (e.g. Überauth that comes with great examples) to handle token on each subsequent connection request.
I am working on a project which is basically a Customer Feedback Analysis Dashboard. There are few graphs on the dashboard and data for each graph is fetched from the server through API requests.
Right now the dashboard is updated every time the page is refreshed. I want it to be updated immediately when there is a new feedback in the system. I am confused, whether I use websockets to send data for each graph or just a flag and use that flag to fetch data through API requests.
Like, facebook/twitter does. They tell you about new posts/tweets and when you click that button your feed/wall gets updated.
If you want to "push" data from server to client and you want that data to show up in a timely fashion (e.g. within 10-20 seconds of when it was available on the server), then you will want to implement some sort of "push" solution where the server can efficiently push data to the client whenever there is new data to send.
There are several possible approaches:
webSockets
socket.io
Server-sent events
Mobile platform-specific push (Android and iOS)
For a general purpose solution that works within a browser, you will want to use one of the first three. socket.io is built on top of webSockets (it just adds more features) so architecturally, they are similar.
Server-sent events are fairly new (modern browsers only) and are only for one way communication (from server to client). webSockets can be used for communication either way.
I'd personally recommend socket.io because of the features it offers (such as automatic client reconnection) and a simplified messaging layer. You can see the feature difference between socket.io and webSockets here. With socket.io, the client makes a connection to the server when the web page is loaded and that connection is persistent. After the connection is established, then either client or server can send messages to the other at any time in a very efficient manner.
Other useful references:
Push notification | is websocket mandatory?
websocket vs rest API for real time data?
Why to use websocket and what is the advantage of using it?
What are the pitfalls of using Websockets in place of RESTful HTTP?
Ajax vs Socket.io
When taking a look at the Pusher Servcer and their Client / Server API I am having some problems trying to figure out how Pusher will help me allow bi-directional communication between devices / apps.
I am having multiple smaller devices / apps in the field that should return their status to a server or another client, which acts as a dashboard to browse all those devices and monitor status, etc.
In my understanding this can be done using traditional WebSockets and a cloud-server in between which manages all connections between those clients - something I though Pusher would be.
But after reading through the docs I can't really see a concept of bi-directional data communication. Here's why:
To push data to the clients I have to use one of Pushers Server Libraries
To receive that Data I have to use one of Pusher Client Libraries
This concept however does not fit into what I need. I want to:
Broadcast to Clients.
Clients can send Data directly to Clients (Server acting as Gateway / Routing).
Clients can send Data to Server.
Server can send / response to unique Client.
When reading about Pusher, they state: "Bi-Directional Communication" which I currently cannot see. So how to implement that advertised Bi-Directional Communication?
Pusher does PubSub only. Using this, you can simulate bi-directional communication: Both sides of the conversation each need to have a topic dedicated to the conversation, and you then publish to this.
This is not ideal. For something which is probably closer to what you seem to want, take a look at WAMP (Web Application Messaging Protocol), which has more than just PubSub. There is a list of implementations at http://wamp-proto.org/implementations. For a router I would recommend Crossbar.io (http://crossbar.io), which has the most documentation to help you get started. Full disclosure: I am involved both with WAMP and Crossbar.io - but it's all open source and may just be what you need.
I am trying to build a simple server/client application where the NanoHttpd server communicates with the client using WebSockets.
The server replies back with the same text that the client sent.
Is it possible to broacast messages to all the clients connected?
Any links about Nanohttpd with multiple-clients connected would be helpful.
https://github.com/PathikDevani/NanoHttpd-Demo
check my github project. here some example for multi user handle on websocket.
-------link is broken now
I want to create a messaging service that uses the XMPP protocol. How would I implement the server-side as well as the client side aspects of this service? I know I would need a server (like Jabberd 2) that runs the messaging framework. How hard would this be to set up and get running? Also what would be the best way to hook up a client program into this service? How would i start pushing messages from one client, through the server, to another client?
Server: there are many out there, see http://xmpp.org/software/servers.shtml for a list.
I've used OpenFire in the past, it's fairly straightforward to set up.
You can add a library like xmppframework to your Cocoa project to make it a client, and configure it to talk to your XMPP server.
Each client gets an identifier (called a 'jid') of the form: uniquetext#xmppserver.name, and you send messages from one client to the other by addressing them to the jid of the intended recipient.
If you want to play around with simple examples in a scripting language, you can use something like the examples in the python xmpp library to see how it all works. Use an xmpp client like psi to connect as one jid and use the examples to connect as another jid to send/receive messages through the server.