I'm building a webapp that has a mobile app companion. The mobile app can be used in offline mode.
What is the best way to keep the central database and the local database on the client apps in sync?
In this case, changes could be happening in the webapp and also on the local app in offline mode. How do I make sure that when a network connection is available, that both databases are in sync.
Keep in mind that the local app would only have a subset of the data. Ie.. only data pertinent to that user.
This seems like a common use case for apps. Is there an available framework for this?
Thank you.
Related
I am building a UWP app that targets both x86, x64 and ARM platforms. I want to replace the current implementation that uses Azure for the backed (an App Service and an SQL Server) because of the high price and because my Pay-As-You-Go subscription does not allow me to set a spending limit.
I thought about using a local database but I don't know if that could be a solution since I want the user to be able to have his data synced on both PC and phone for example. I am also ok with renouncing the idea of a structured database in favor of structured files (like xml) if I can find a way to keep them somewhere in the cloud (and then I can read/write them from the client app - no need for App Service).
Are there any free, non-trial alternatives to Azure? Or should I look more into the file storage implementation? Thanks in advance.
Instead of Azure you could use another web hosting solution to publish you API. Azure also offers small free plans that might be sufficient.
An alternative would be to request access and store/sync data to user's OneDrive. Each logged in user with Microsoft Account should have OneDrive storage available so this is a good middle-ground, which is still free for you. A nice introduction to this can be found in this article.
UWP also offers RoamingFolder where you can store small files that are synced across the devices that you use. Unfortunately this is less reliable because you are not able to control when the sync happens and cannot resolve conflicts.
I have successfully migrated to another cloud platform: Heroku. In my opinion, at least for small apps, Heroku offers the best solution both technology-wise and price-wise.
I am now able to have a webservice hosted for free in the cloud, without worring about traffic and number of requests. Of course you can scale up if you want better performance, but you can start with a free plan. Also, I have a postgressql db hosted also in the cloud, also for free (up until 10 000 records, and it will be just 9$/month if I want to upgrade to 10 milion). One can never found an offer like this free on Azure.
I had to learn a bit of Node.js (there are a lot of languages Heroku supports for backend services, but .Net is not one of them) but it was totally worth it!
Another option that is now starting to gain more and more popularity is FireBase. I will certantly also check that out for my future apps.
we have an app which uses JSONStore to support offline, if device is offline and user submit data it stores it offline, now when device is online and when user login to the app it sync with server and submit all data to server.
the question is, Is it possible when device comes online then my offline data sync with server without user open my app ?
Does worklight support that? Or I have to do something else?
please advice
Like Idan said, Worklight does not support this, but depending on the OS, it could support it.
For instance, on Android, you could use BroadcastReceivers to detect changes in network connectivity, and execute an action when it happens, regardless of whether your app is closed or not.
Here is the API for the receiver: http://developer.android.com/reference/android/content/BroadcastReceiver.html and here is a SO answer explaining how to use it to detect WiFi connectivity: https://stackoverflow.com/a/22626736/2245921 So you can modify this BroadcastReceiver to run the sync code that you would normally do if your app was already open.
If you are using any other platform (iOS, Windows) there might be an equivalent that you can use.
Also, keep in mind that if you are doing a hybrid application, you can create your own Cordova plugin to execute native code from Javascript. Here is the documentation on how to do so: http://cordova.apache.org/docs/en/3.5.0/guide_hybrid_plugins_index.md.html#Plugin%20Development%20Guide
We are currently planning to develop a suite of Windows Store Apps. They are independent and fully work alone, but they are related and act in concert. If a user has several of them, they should share some of their settings (and data), so that the user does not have to manually change these settings in every single one of them.
Is such a scenario even intented?
And how to implement it?
Registry: Does not work. Apps cannot access the registry.
ApplicationData (LocalFolder, LocalSettings etc.): Does not work. Apps cannot access the data of other apps.
Cloud services: Kind of works, but only when the machine is online. Our apps should work offline, too. And we would need to create/rent such a cloud service, which would cause additional costs.
KnownFolder.DocumentsLibrary: This –currently– looks like the only solution to me. The apps are already saving and sharing data there, so let's just save our settings there, too. But the name of the shared folder is one of the settings! And Windows Store Apps cannot create hidden files, so the user can see the settings file. This makes this solution a bit... "rough".
Any other ideas or additional information I have missed?
If you want them to sync with each other instantly, even when the device is offline, then that's your only option. Windows 8 Apps are not intended to share settings.
So much want of sharing.
Roaming API will only share with the SAME app, the SAME user, ANY W8 device.
SkyDrive will only share across ANY app, the SAME user, ANY device.
Using Azure (or any web service) will share across ANY app, ANY user, ANY device.
Don't do this
Don't use the register, the API is not supported
Don't use the file system, the boundaries cause your app to be brittle
Don't use ApplicationData.AnyFolder, this is restricted to a single app GUID
You had might as well get "instant" out of your language, man. That just doesn't happen. But you can have fast (let's call it near instant); you can use Sockets or SignalR to connect your client to some service out there with nearly instant responses. A less sophisticated approach would be to poll from your client, too. It has served developers for decades.
I am making an app for the iPhone in Xcode which needs to be able to send and receive excel data from a windows based machine. Making the app is no trouble but what would I need from a PC to access the app data?
Firstly, I wouldn't be using Excel as a data storage program. What you really should be using is a database hosted on a web server with a PHP interface etc. If you choose to go the database route, then you can easily use a Windows machine.
Though if you choose to stick with Excel, it would be theoretically be possible given that people have made apps to have full control of a computer remotely via an app. I just think that this approach is going to be very hard to set up, and will be a lot more clunky than any sort of web server set up. Don't forget that you can get free web server services if the data level is low.
As you mentioned, this PC won't have access to the internet. Assuming you aren't willing to fix that, I guess you'd be left with a Bluetooth or local wifi option. Having to plug it in would really defeat the purpose of an app, and I don't think that iPhones can even do that without mad hacks.
An alternative idea is to build an app that links in with some free web server service, then build VBA code to download it to your Excel sheet. When you plug your iPhone into your PC, use the hotspot to get internet access.
Hi exalted sages of the development world,
I humbly come before thee with a noob question. I'm actually pretty excited about Windows 8 Metro HTML5/Javascript development, but I haven't dived in to it yet. One initial question that immediately came up that Google has failed me on so far is how do I do local data access with metro HTML apps? I understand that I can use some of the new HTML5 local storage features, but what do I do say if I want to have an application that writes/receives data to say a SQL CE database on the local machine as opposed to a remote one? Is there some kind of programmable built in object that I can access with Javascript to do data manipulation with that would take the traditional place of a web server?
Thank you for your time.
There is no client for SQL access in WinRT. To access such databases, you have to create a web service and call it (similarly to Silverlight). WCF RIA Services are supported for this.
To store and retrieve data locally, there is JET API. HTML and JavaScript apps support IndexedDB. All these options read and write data to the app’s isolated storage; they do not enable free access to the file system.
Taken from http://www.itwriting.com/blog/4874-data-access-in-windows-8-winrt.html