I'm trying to make an iOS 5 app that features real-time things coming from the server. It will only use these whilst the app is running.
To make it real-time without polling I have been evaluating two design routes:
Creating a socket from the app to the server, and exchanging information via streams.
Pros: Relatively simple and would not involve a 3rd party.
Cons: Battery life drain.
For an overview of how this might work, check
out this excellent tutorial:
http://www.raywenderlich.com/3932/how-to-create-a-socket-based-iphone-app-and-server
Using standard HTTP to communicate with the server, and with each request from the app let the server know what they are viewing. If something new is available for user, send an Apple Push Notification (with no visible alert) to let app know it can go and download new thing.
Pros: Not opening up a new TCP connection, so battery life not drained unnecessarily.
Cons: Feels like a poor hack.
The official docs on APNs http://developer.apple.com/library/mac/#documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/ApplePushService/ApplePushService.html
I think a socket would be the way to go, but before I commit to it I wanted a second opinion, as this is the first time I've made anything like this!
Sockets would be my choice. I do not know how time critical your application is, but sockets might perform better as APNs if realtime is a must.
Does it really need to be "full real time"? From my point of view i would prefer http since it is already well integrated into the iOS SDK. Its easy to understand, maintain and implement and plenty of documentation is on the web. So maybe a http poll every minute or so will be enough (depending on the app and the number of users). Please consider firewalls too! Traffic to unknown ports maybe denied due to firewall policies of provider or local wifi. So if you really need realtime connectivity I guess you have to use sockets.
Related
If you had to open a resource from a database in a web browser on another computer, using an Apple tablet app as a remote control, how would you implement such a feature? This is basically what WhatsApp Web does, so it should be technically possible. But how would you go about it?
I'm assuming that you mean a situation where the app modifies something on the server, and the browser then updates automatically to reflect this. If you mean something like the iOS Remote app, then you may have to use another method (and you may not be able to do it from the browser).
To do this you'll have to have a server that both the iOS app and the browser are connected to. When the app does something, it updates the server, e.g. by submitting an HTTP request to a REST API. The server then updates the database.
Now you have to get the browser to update, and there are two ways of going about this. One is by polling the server periodically, using AJAX to update parts of the page dynamically without refreshing the whole page. This works, but there's a lot of overhead and it can be a drain on a laptop battery.
The better, but slightly more difficult to setup, alternative is to use WebSockets. WebSockets allow for two-way communication between server and client, and the connection stays open until one party closes it (or it times out after a long time). The client can submit information to or pull information from the server as before, but the server can also push information to the client without the client having to request it. This would typically be how games, chat clients, etc. can operate nearly in real time.
Setting this up isn't necessarily that difficult, but it's a very broad, open-ended topic that's beyond the scope of just iOS development. Beyond the iOS app and the web client, you'll also need a backend that's capable of using sockets. Node.js is a popular JavaScript-based backend for this sort of application; there are numerous others out there as well. You'll have to do your own research to determine what's right for you.
I just wonder why and for what kind of application or case we need the Socket.IO.
I am the iOS developer of a known open source project socket.IO-objc
Usually, we need HTTP or HTTPS to communicate with server. The socket aims to conduct real time communication (It should always keep a live HTTP connection.)
Libraries like socket.IO are needed when we need real-time in our app. Let me explain this in little more detail. Let's assume that you are developing a game, which is multiplayer and 2 or more users can play that simultaneously. Then, in that case, you won't be making HTTP or HTTPS calls because of many reasons and one of them is that their packet size is large and other is that these calls are very slow. In such scenarios we use libraries like sockets to send and receive data to and from the server. Sockets are really fast and are capable of sending only those data packets which are needed. Using HTTP programming you can never create any multiplayer game or any app which will be interacting with a server on a realtime basis.
Let's take another example. Let's assume that you are working on a chat application. When user A is typing something then user B should know that A is typing (similar to gtalk of facebook messenger). If you will use HTTP calls at that point of time then "B" will never be able to see the actual status of the other person because of the delay. So what we can use is sockets so that when user A is typing anything then his device will send only one data packet which will just notify the server that he is typing and will be delivered to user B, this process is really fast (almost realtime) and will reduce the data transfer also.
I'm working on chat application using socket.io also. So it seems to replacing everythings with socket.io. This is making me in doubt and curiousness. I totally agree with real-time app like chat suits for socket.io. However there is round-trip communication (such as user login) that's more suitable for HTTP.
Socket.io uses web socket to pass data among users who are all connected to a web server. With web socket, there is no negotiation protocols and connection remain open as long as users concerned are registering for service with the web server. As pointed out also, the payload is significantly less than http/https protocol.
Socket.IO is a JavaScript library for realtime web applications. It enables realtime, bi-directional communication between web clients and server. It has two parts: a client-side library that runs in the browser, and a server-side library for node.js. Both components have a nearly identical API.
I am building an app that needs to use push notifications. Currently it is only an iPhone app and i have already implemented a manual version for push notifications.
There are quite a few services that do this kindof thing for you... Are there any benefits to using them? Having a nice API is not really relevant because of the fact that i have already implemented pushing manually.
The main reason i ask is that i downloaded the app Path and noticed that their push notifications seem to be a lot faster and a lot more reliable than my app...
Btw, Im using GAE for the backend.
Thanks
The most obvious benefit to using a push notification provider is not having to write the code yourself. Writing an efficient and reliable provider of Apple Push Notifications is not simple. If you want a quick solution and are willing to pay for it, using an existing provider is probably the way to go.
In my opinion the APNS API is bad. The fact that you don't get an acknowledgement for a successfull notification makes it hard to code a reliable provider. If you want to make sure you're not missing error responses from Apple, you have to attempt reading often from the connection, and with large timeouts, which will make your provider slow. On the other hand, if you want to send your notifications as quickly as possible, you'll have to sacrifice the reliability (because you won't be able to rely on getting all the error responses that Apple send). Of course, if you make sure that your DB doesn't contain invalid device tokens, and that you always send valid payloads, you can assume that you won't get error responses from Apple, which would allow you to send notifications quickly.
That said, I'm not sure how reliable and/or fast are the existing APN providers.
The best way to be sure of the quality of the provider you use is to write it yourself (unless you are willing to spend the time on testing the reliabily and speed of existing providers).
I have a situation where I would like to communicate between 2-4 devices over the 3G network (it should also work over WLAN, but 3G solution is critical).
Every device (except one) asks for a GPS-location every ~5 seconds, but when this process is cancelled by the user of that device, one device needs to be informed of this event.
I was thinking that one device could act as a server, and the rest as clients that should connect to the server. Is this possible over the 3G network?
I've also read about push-notifications, is this relevant here? Can you receive notifications without disturbing the user with a popups etc?
Are there other ways?
Basically I would like to use apple "standard" solutions (if there are any) before diving into eventual socket-programming or anything similar...
What I would like to avoid is to have a webserver or some similar "3rd-party" solution, because I don't want many users to simultaniously connect and "pull" from the same external server in a final solution...
UPDATE:
Basically my application will have thousands of users that will need to be informed if an even occurs. Also this happens simultanously ~5 second, what would be the best solution to reduce load and avoid spamming?
I was thinking that one device could act as a server, and the rest as
clients that should connect to the server. Is this possible over the
3G network?
It could work, but having a dedicated server would be a better choice
I've also read about push-notifications, is this relevant here? Can
you receive notifications without disturbing the user with a popups
etc?
In your case no, since you will need a server to communicate with apple
Basically I would like to use apple "standard" solutions (if there are
any) before diving into eventual socket-programming or anything
similar...
There are no standard solution, other than you should probably rethink about using a dedicated remote server for this
iPhones can't communicate directly with each other using 3G. You can access the internet through the 3G, but you can't do peer-to-peer as you are suggesting. If you were close enough, you could use bluetooth, but I expect you are too far away.
You would have no way of detecting the one device that acts as a server from the other devices. The IP address could (and probably would) change every time the device connects to a mobile data network. You would need a central server to co-ordinate all of the clients.
You have multiple questions, but I'll try to address as many of them as I can:
I was thinking that one device could act as a server, and the rest as
clients that should connect to the server. Is this possible over the
3G network?
No, you cannot run a server on a iPhone/iPad that is accessible over 3G without an external website acting as an intermediary. (You can run one that is accessible over Wi-Fi, but this does not solve your problem as stated.)
I've also read about push-notifications, is this relevant here? Can
you receive notifications without disturbing the user with a popups
etc?
Push requires you (or a third party contracted by you) to have a web server, so if you want a server-free solution it is not relevant here.
Are there other ways?
Over 3G you will, under the current Apple restrictions, always need an external server.
Basically I would like to use apple "standard" solutions (if there are any) before diving into eventual socket-programming or anything similar...
Diving won't help you here. Even using low-level socket programming you will not be able to run a server on an iPhone accessible over 3G without an external website to aid in establishing a connection.
You can try using GameCenter. The mechanism of network games in Game Center allows connect up to four players with no third-party solutions.
I am looking for ways where my RESTful web service can let my iPad app know to update its cached data when the server's data has been updated. The server is running on Tomcat & Apache Jersey.
Is this doable? And not using Apple Push Notification (APN)?
There are essentially two options: heartbeat check from the app to the server (on a timer) or something that keeps the line of communication open, such as web sockets. Here is an open source web socket for iOS, but I have not personally experimented with it:
http://code.google.com/p/unitt/wiki/UnittWebSocketClient
I'm not sure why you want to avoid APN, but this really sounds like what it's made for.
If you want to update only when your app is running, there are other options (straight forward polling comes to mind), but if you want the user to be notified even when the application isn't running, there isn't really any other Apple approved way to do it.
Can reverse the design around and make your device a client and pull data from a REST service at a regular interval?? With all the support one gets from REST, it might be helpful to know you will have complete control of when data is being pulled by the device from server and exactly the data that might goto device.
I'm curious to know your thoughts, Thanks.
I'll be building a web-syncing iOS application soon, and we're going to use RestKit. Take a look, it might be a big help.