I working on a project were mobile users can receive alerts based on diferent factors, the server side will be implemented using the MVC framework.
My question is regarding the client side; what would be the most efficient way to send the alerts to the clients? is there any way to broadcast the alerts to each device or do I have to set up some system where each device pulls the data from the server on an interval of mins/seconds? I am afraid pulling the data every X secs/mins would create an unnesesary overhead on the mobile devices.
One way would be using SMS but SMS gateway services are expensive and not on my budget right now.
I haven't personally tried it, but this service might work for you:
http://www.airgramapp.com/api
It is free for limited use. Downside is it appears to be a separate install on the mobile device. This might means less control of the content of the message or its look. Upside is it looks quick and easy if you just need a proof of concept at this point.
Related
I want to create a realtime stock alert app where users can subscribe to specific stock instrument with target price. Once that target price hit, The subscribed user will be notified over the app.
A good example of such platform is Tradingview.com
For stock API's I will be receiving realtime stock quotes from My API vendor over.
As far my knowledge is concern, I'm looking at this app as Web socket OR MQTT pub/sub platform where users can subscribe to that specific instrument topic and get notified once stock price is hit.
But my knowledge is limited when it comes to thousands of users subscribing to thousands of alerts.
What technologies must be going at the backend for such kind of apps ? What must be the data flow ?
Bit late answer to this, I was working on something similar with all custom NodeJS server and instruments you want to subscribe on. It is very simple server and you can find it here https://github.com/markosole/yahoo-node-streamer
I am working on desktop App built on top of Electron which is used for subscribing to instruments, monitoring multiple instruments and creating visual and sound alerts for every instrument individually. I have not release Electron app source to the public yet.
Creating mobile app will be harder as it would require backround data and best bet would be using Flutter and Google Firestore to send alerts. Well this is very top level.. I will eventually make flutter app and share it on Github
Overlooking the fact that there are literally thousands of apps out there that do all of this already....
Your best bet might be to do one of two things:
1) Just send out the stock price and let the client app figure out the alert, or
2) Have a back-end system that just sends out the alert to the specific customer when their price point is reached.
Option 1 is something that MQTT could easily do. Option 2 could be done using MQTT, but its something of an overkill IMHO. MQTT is built for applications where one node is publishing data, and many nodes are subscribing to that data -- hence Option 1 is more in line with what MQTT was built for.
Why can't the individual app servers directly send notification to their mobile apps ? What is the benefit of having a centralized notification platform ?
From this thread, GCM is a service that helps developers send data from servers to their Android applications on Android devices. Same with APN which is a service for app developers to propagate information to iOS (and, indirectly, watchOS), tvOS, and macOS devices.
You may check these threads:
Why it is preferred to use GCM for push notifications?
Let's say you have 50 applications on your phone that do not use GCM. Each app developer decides it is appropriate to poll their respective backend once a minute.
Since these are all separate applications, each call will likely not happen at the same time as another api call. The biggest kill to battery is when the radio within an android device has to turn back on after being off to make an API call, so multiple calls happening with blocks of time in between drains battery faster (read this article on the radio state machine to better understand why this is https://developer.android.com/training/efficient-downloads/efficient-network-access.html)
In addition, each application will be hitting a separate endpoint. Each time you make an API call, you have to go through the connect process for a given server. With batched api requests or HTTP 2.0, multiple calls going to the same server can be optimized by not having to re-do a handshake or the connect process.
What are some advantages of push notifications?
Wide reach across internet users.
High conversion rates.
Real-time communication.
Push Notifications Explained
Hope this helps!
I wonder to know which technique and tools I should use to have the ability to send real time notifications to users. Specifically if I build a messaging system.
I can see that modern social networks can send notifications about new messages almost immediately. Even when the user 'A' from one country writes a message to the user 'B' in another country you can see that the user 'A' writes a message and you immediately see it (even if those users live in different continents).
I tried to figure out how it is possible and find any information about this but without success.
The only thing I found out is the technique when we use a Redis or RabbitMQ server with several servers which acts like publishers and subscribers. Our API servers receive new messages then they push a new message in the queue then subscribers receives the messages and if they have an open WebSocket with the recipient they push this message in the WebSocket and a client receives the message.
But it really won't work if you have a distributed project and your clients are connected to the nearest servers in the nearest data center.
The question is: what technologies/techniques/anything we should use to be able to build notifications in a distributed project?
If you develop your distributed app/system using web technologies, you can consider building what is referred to as a Progressive Web App. With PWAs you can add push notifications in a relatively easy way. You could start with a PWA approach, and then decide later on if developing a native app as well (i.e. iOS or Android) would be necessary.
There are many resources to learn and guide you in developing progressive web apps. Check the references I mentioned above, and you can do this codelab as a starting point.
I want to start to create a website which is opened on a mobile phone (any kind of smartphone). This website will have the feature to control a website you have already opened on your computer. (The Volkswagen New Century Beetle from 2011 had the feature, that i could scroll via smartphone on the website opened on my desktop computer)
We have a streaming website for horsevideos, and this will be an awesome feature for our customers, if they could watch the streams on their smart tv and control via iphone/android/wp.
Also wilmaa.com from switzerland provides a remote control for smartphone to navigate on my website on smart tv/webbrowser.
Because I need a starting point to learn how it works i was checking Google, maybe there already any remote controls outside, but unfortunately i couldn't find anything.
Maybe Stack Overflow can help me by giving some starting points on how to realize this.
To do this you need some kind of 'pushing' service able to overcome the inherent drawback of HTTP that it has always been a 'pull only' system - client initiates a request, server answers. In this case you want to push an event from the server to the client.
For the past years this has been done with so called 'long polling'. This means that you 'abuse' the mechanism present in browsers that protects the server from hanging requests, but allows them to take a while. Apache is by default configured to allow a request to last 300 seconds on most platforms. Long polling works by sending an Ajax request, and if the server has no data, instead of sending that back it just waits, until either it does have data, or a long period such as a minute has expired. The client does not send a new request until it has received a response. This gives the illusion to the end user of real time feedback, and is how sites like Facebook et al have done this for years.
Since a few months it's also possible to employ a new HTML5 technology that now has stable implementations on all major browsers: Websockets. This technology allows a server to upgrade a common pull request to a full bidirectional connection, allowing realtime communication between browser and server. Regrettably, the 'regular' webservers such as Apache are not really built for this kind of logic, although it is possible to emulate it with frameworks like Ratchet. For the realtime part of the system the current platform of choice for most sites, including Stack Overflow here, is node.js - serverside asynchronous Javascript.
What I would recommend in your situation:
Set up a separate node.js server as an event dispatcher (you can get a cheap micro sized EC2 instance at Amazon for like $15 per month which will probably suffice, and is very scalable)
Keep all the other code in the regular environment where it is now, just add logic to communicate with the event dispatcher
Deploy Socket.io as your websocket handling service. It simplifies all the Javascript logic on both server and client side, and wraps a realtime connection in such a way that it's even compatible with IE5.5, by gracefully degrading towards technologies that are supported by both server and client - websockets on recent browsers, long polls or other technologies on legacy systems.
With this solution you can easily implement, with relatively little code, a system with full realtime responsiveness across multiple platforms as you described.
As for the controlling app itself, just use HTML5, with Phonegap if you intend to distribute to app stores.
I'm looking at having thousands of simultaneous connections from mobile phones to the server whereby anytime a user interacts with his cell phone, the data is sent and logged by the server. Also, anytime the server has new information for that user, the server can push that information without a browser refresh. I am wondering what is more stable and how you would build this?
A good real-time framework or infrastructure will have numerous APIs that should let you connect any device, no matter the technology, to the real-time server e.g. an iOS client library for iPhone and iPad, a JavaScript client library for numerous platforms including normal and mobile web, an Android compatible Java library and so on.
An interesting idea might be to choose which ever framework or real-time service suits your needs best and then using something like PhoneGap. But, as #rt2088 says, it depends if you need the notification app to be running as a service on the phone or as a standalone application.
The choice will also depend on whether you want to install, host, maintain and manage the scaling of your own real-time services or not. If not, there are a number of services out there who you could use so you can concentrate on building your application. If you do want to manage your own infrastructure then the Comet Maturity guide could be a good start. It's a little out of date but is still probably the best reference available.
the ability to push new content the
user based on his GPS location which
is "pinged" to our server. Based on
that, we deliver local content. What
frameworks are you talking about?
There are a number of real-time frameworks available at the moment. Some are hosted services and others require installation on your own hardware. The majority of them will come with a bunch of libraries in different technologies that make it easier to get up and running with them e.g. a JavaScript library that wraps the WebSocket object and also manages fallback for web browsers that don't support WebSockets.
I've just created a Real-Time Technologies Guide in which I've listed all the real-time technologies that I could think of and provided a bunch of tags associated with each.
wouldn't a javascript client library
cover all platforms if it is a web
appilcation?
If the application is a web application then yes, a JavaScript library would be all you need for the client application. The server side libraries that you require would depend on the real-time technology you choose.
Best solution to achieve this is to use the WebSocket communication. It is bidirectional asynchronous communication. Currently every browser supports this new standard and plenty of code snippets available. You just have to google it. There are many server and client side frameworks. choose the one best suits to your requirement.
The details of the WebSocket specification is available at -
Websocket specification
Do you need notification when user uses mobile browser of handset or the mobile handset itself (performing non-browser tasks)? Based on that, the framework to record user activity can be selected.