I have an issue on firebase; the listener is connected to realtime database with personal hotspot and gets updates from database correctly, but when the hotspoter changes the network quality from 3G to LTE (or another, doesn't matter), the listener starts to not get updates from realtime database anymore. How can I detect this issue?
The Firebase SDK uses various mechanism to detect whether the socket it uses to communicate with the server is still active, but unfortunately these are not always reliable on all (especially) mobile providers.
You could enable debug logging to see what the SDK is going during those 10 minutes, or you could detect the network switch yourself and call goOffline()/goOnline in quick succession so that the SDK creates a new connection.
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I'm looking for a way to managing and controlling IoT devices without the (constant) need for a remote server to be part in it and with a PWA instead of a native application on the managing device. The resulting goal is an IoT device that keeps working when a product eventually goes obsolete (no more server running/allocated) and having an application that has PWA benefits like always up-to-date, easy to replicated and cheaply hosted on something like S3.
As an example, let's say I have one or more IoT devices of different classes like an ESP8266 and a Raspberry Pi for instance. Just as with any new IoT device I want to add it to the network and from there on manage its state from an app. The app in this case is a PWA instead of full blown native app.
1) Traditionally, in the initial setup a native app would scan for wifi networks, connecting automatically to one that has the right name. Using PWA's we are limited to just the "state" of the network. So users would have to manually switch to the network of the newly connected IoT device. This is okay.
2) Next up, the user would need to enter his/her wifi credentials. There might be methods to set this up automatically using a native app, but I don't believe this is the case on a PWA. This, also, is okay.
3) The device then restarts, tries to connect to the network set up in (2). If set up correctly it should get its IP using DHCP. And now things get difficult. I want to 'discover' that network from my PWA. There used to be a way to retrieve the IP from a device using the WebRTC API. but that since has changed to show an obfuscated mdns that resolves to localhost. The ip leak would have allowed for a browser based network scan, but that is no longer possible. I always hoped that Android would default to using a users router as a DNS server, but that is not the case. The result is that simply using an mDNS isn't an option either. I do not want user having to check their router, install an app like fing or do anything else that disrupts the flow from a UX perspective.
Step (3) needs to run every time the app starts so you'd want something reliable. Scanning for devices isn't possible using a PWA, so I need to find another method. I was thinking of something like the way Docker containers can find each other in between networks (see etcd for example), using a predefined key that is shared during installation. The problem with this, is that it requires a remote server to store the IPs attached to that key. I don't want that.
Ideas on how to solve this are very much appreciated! I want to be able to offer a solution that would work even when WAN is out. That being said, I am aware that a connection to a remote server is needed if the end user would want to enable any voice assistant or wants to control a device from WAN.
I want to run a server on Windows Phone 8. It is important that the server keeps running even if the user opens another app or the screen lock turns on. Relying on an internet connection is not an option. It should work in a local network.
UseCase: The server is needed for a multiplayer game. The idea is that one player starts a local server. After that, all players (including the player who starts the local server) can connect to this server using a webbrowser. The server delivers html and responds to ajax calls.
It seems that PeriodicTask and ResourceIntensiveTask do not fit my needs. Is that correct? How can I run an app in the background that is always listening for incoming tcp connections?
I don't know a clean way. But if you're happy with a hack: You could use the Geolocator. This blog gives a step by step guidance: How to create application which executes in the background on Windows Phone 8?
As most of the hacks, this brings some problems and questions (probably more than I mention here):
If the user turns off the GPS, your server won't be reachable anymore.
I don't know how strict Microsoft is with what you can publish on their store.
No way to do this on Windows Phone.
I am currently writing an iPhone application that sends and receives JSON data from a remote server to essentially display realtime information. Me and my partner started the project using Google App Engine (Python) for the server-side implementation mostly because it was easy to pick up and seemed suitable for our needs at the time. However, we're only just now starting to see the downsides of the framework for realtime iPhone apps - APNS is not at all supported, and neither is the GAE Channels API. So our only option for displaying the realtime server data on our app is to continuously poll the server, which certainly seems like horrible design.
We'll have to port our server-side code to a new framework. My question is, which one do we use? From numerous searches, I still have yet to find a satisfactory answer.
I should mention that I don't necessarily want the server to send push notifications. I just want to be able to push data to clients in real-time, and then manipulate that data on the iPhone client-side code. We're fine with setting up the framework on a local server if we have to.
Since you don't want to be pull data in background (lett alone if it is even possible)will have to use APNS.
But why switch away from google app angine, you could use an APNS provider like Urban Airship wich provide there on API to connect with.
You'r not even the fist to run into this problem: Apple Push Notifications on Google Appengine
Probably the easiest realtime framework you can use for sending data to iOS clients in real-time is PubNub (http://www.pubnub.com). It's reasonably priced, and it scales to anything you can throw at it. In my experience, it has no problem delivering a message to an end client in under .25 milliseconds (regardless of the number of clients it's being sent to).
Their latest version also supports APNS functionality for when you app isn't in the foreground.
https://github.com/pubnub/objective-c/blob/master/iOS/README_FOR_APNS.md
If you want to create your own APNS server (since you are running on App Engine anyway), there are examples of how to do that using App Engine's new Socket API. I've written a demo python AppEngine application that people might find helpful in this regard.
https://github.com/GarettRogers/appengine-apns-gcm
I understand that some applications need to check against a server periodically, but why don't servers let a mobile device know when it's time to update.
For example, let's say you receive an e-mail in gmail. As it stands now, there can be a delay between receiving the e-mail and your device notifying you. I assume this has to do with waiting until the device has checked the gmail server, at which point it sees the new e-mail and notifies the user. It makes more sense to me that when the gmail server receives an e-mail, it should ping (or however the creator wants to implement it) all registered devices to let them know that it's time to update. This way notifications would be synchronized and mobile device could save battery by not having to periodically check a server.
What you are describing is called a "server push". Some mobile applications does use server push. And Google actually have a technology in place to make this easier to implement, named "Cloud to device messaging" (C2DM). It works by having the servers sending a tiny little message, via googles C2DM servers, to the application running on the device, informing it its time for a update. And the device then retrieves the actual update from the original server (not from C2DM).
Its good stuff. It allows the service listening for C2DM manages to wake up the phone and everything. The downside is, the user of the application needs a google account. For android users, this isnt really a downside though.
Except they do, in some cases. In the "Mail, Contacts, Calendars" section of Settings on my iPod, there's a submenu labeled "Fetch New Data", which contains an option to have the mail server or whatever "Push" the data to the iPod. The Fetch aspect, which you can set the schedule for, is for when Push is off or you're syncing with applications that don't support push.
That is how Android does it. It pushes notifications to the device and that api is open to third party developers as well so they can push notifications to their users.
That thing is it is difficult to know the address of a mobile device at any particular time, the I.P address is dynamic, on a server the address is much more stable, so the device knows it will always find Google at google.com but Google has no real way of knowing where to find the device, it wouldn't know where to ping in the first place.
This is where push comes in, there are different implementations but i think they work by having the device maintain a connection to the server, and reestablishing it if its lost.
See http://en.wikipedia.org/wiki/Push_technology
This of course is much harder to implement and maintain then a simple client pull.
I have a requirement to promote 3G/GPRS over WiFi connectivity in the iPhone application I am developing. Please let me know if this is possible and if yes, how?
The problem is when I have a WiFi network which is available and connected but not logged in using Captive Portal, I cannot use that WiFi network to perform the tasks which require internet connection. What i have noticed is Reachability API detects the available WiFi but I cannot use it as I am not logged in and so I am not connected to internet using this WiFi hotspot until I login. So I want to use 3G/GPRS to perform the tasks requiring internet connectivity.
iPhone's default behavior is it uses WiFi when its available and if not then only 3G/GPRS.
So please let me know if both 3G/GPRS and WiFi are available but I am connected to internet not using WiFi but 3G/GPRS how to use 3G/GRPS to perform the tasks requiring internet connectivity.
Regards,
Third-party applications don't get control of where their data comes from. About all you're going to be able to do is ask your users to turn wifi off while your application does its thing. If you need to get back onto wifi after doing the initial data transfer, you could make some clever use of the iOS 4 multitasking and local-notification APIs: when your application enters the background, it could start a background-task handler (using -beginBackgroundTaskWithExpirationHandler: in your app delegate's -applicationDidEnterBackground:) to wait for the wifi connection to become unavailable, do its thing with the cell network, then create a UILocalNotification to tell the user it's okay to turn wifi back on again. That way, the user could get the benefits of whatever your app does and still keep the connection they started out on.
If you are creating an app which needs to access certain network resource(s) to function, then you should just ping, or try to connect to those resources directly instead of just depending on reachability for the decision. If you can't ping your server, then have the app do the same thing it would if reachability reported zero connectivity (even though it may not be).
For security reasons, Apple doesn't allow developer to do such settings pro grammatically, despite you GPRS network connection to achieve some purposes.