I have successfully built an android app for my WordPress blog. The app retrieves the list of posts from an online jSON file, parses it and populates RecyclerView with the data. The last bit of work is notifying the users when I post new content to blog and the JSON file changes.
Please, do you have any idea how I might achieve this?
You should use the push services on both ends (android and firebase).check firebase's docs for how to implement their service.
push services automatically notifies (or posts , you can do whatever you like when the event is fired) the users subscribed to the service.
Related
I am using Flutter for the app and Django with Postgres for my backend APIs. I want to update the data from API in-app to update in real-time, what is the best way to do it. I went through a lot of blog posts and SO answers and have got the following solutions, Any better solutions would be appreciated
Websockets - difficult to scale
Refresh APIs after every n seconds - Difficult to scale
Firestore in build functions but I don't want to migrate to firebase.
Are there any better solutions? I want the solution to scale to many users so please let me know the best solution for this. Thanks
Update:
I have two data sources, one is the flutter app itself and another is a web dashboard, I want the data in the app which is a listview to get updated whenever new data is added from the dashboard in real-time. The data in the app is a listview that should be updated in real time with new records from the API.
Don't know if this is good solution, but you can try to use FCM from Firebase (you wrote only about firestore/real-time database).
Every time app is in reasumed state it can register token in your backend, and every time web dashboard is being changed, server can send push notification to the app with data/trigger to fetch data.
WebDashboard -> Backend -> FCM(with trigger/ full data) -> Mobile
I am trying to make an app in which I am going to use room database for offline data caching and using NodeJs and MongoDB as a backend service.
What I am going to do is when app first opens it fetches data from server and stores in room database from where it shows in database.
My problem is whenever some new data is updated on server how would I know whether it is available in room database and when to fire server request.
Someone please let me know how can achieve this any help would be appreciated.
THANKS
You are going to need to implement some sort of routine where you can check and validate (update) the data. However, this will depend on the importance of the data and rather if it should be updated and how often.
These are some of the solutions you can look at:
Long/short polling - Client Pull
WebSockets - Server Push
Server-Sent Events - Server Push
I would probably use some sort of real-time communication (web sockets) or use a real-time database to notify the app of changes when something needs to get updated. That said it would also depend on the technology, for instance, Firebase already offers offline caching.
You can achieve this functionality in multiple ways
Configure firebase notification in your app, whenever any server side data update happen just trigger a notification, based on that you can call api and store data in room.
Maintain some version code related to updated server side data in your api, based on that version code you can write logic for storing data in room.
I need to display some data from the server via my RecyclerView. The problem is how to notify the application that new data is available in the server. I have seen in some applications where the top of the list has a button with text like "Show 5 new posts." After clicking on that button, the 5 new posts download from the server without downloading the entire list of data. How can I implement that same synchronization?
There are lots of ways to achieve synchronisation in android.
You can use SyncAdapter (Highly recommended).
You can use GCM, push to client if anything new comes up and act accordingly.
Further you can use Local Broadcast Listener to notify that view
I think this link will help you to understand the synchronization between android app and server - Sync data between Android App and webserver .
Well in my app, the data from the server is being pulled in Json format and then with costume adapter i'm updating the listview.
But when ever the new content is updated in server how to trigger my app to know that some new content is available now in server. So that app can pull from the server and update the listview.
Just thinking of using GCM, is it a right way ?
Any better idea ?
Push notification (GCM) is the easiest way to go forward for this task. Just fire one push when your server data updated, and on mobile side, when you get push notification at that time just call your Activity and just refresh your ListView (setting whole adapter again or calling notifyDatasetChanged()).
I have an application in hand where we need to use a tab for data entry. The tab loads initial data from the remote server. Subsequently remote server needs to be updated, inserted (for new data) as the user inserts/updates data on the tab. Out database server is SQL Server 2008.
As suggested by the many experts at stackoverflow we are going to use Webservices at the server to facilitate data interchange. However I am still not sure of the following points -
1. whats the best mechanism for authentication in such case.
2. should i take a chunk of data from sqlite table at android, convert to JSON and pass it on to the Webservices for insert/update operation or take single row and update. Though I think sending single row would not be efficient.
3.How I manage failure to upgrade remote server. This is easier in case I use single row. My plan is to set status flag for sqlite records to 1 (default is 0) for records being updated/inserted to remote server. If update/insert fails I change the status flag back to 0 so that i can use them again next time. In case of success change the flag to 2.
thanks in advance
UPDATE
Doen some study and tried to use SampleSyncAdapter. Still some confusion about the whole operation. My Sqlite database is created by a program and content provider class exists in that application. Package name for the application is com.xylo.pds. I am trying to write a sync application which attempts to sync the data used in the first application. If I follow the SampleSyncAdapter sample - I need to develop server side application for authentication and then uploading android data to the server(in my case one way is sufficient). I can do that with the help of server side code given with the sample.
So I just copied codes of the sample code for my Authentication and Sync. My authenticator.xml has the existing entries-
android:contentAuthority="com.android.contacts"
android:accountType="com.example.android.samplesync
So now my application can add account and sync the contact. And no wonder it works with dummy server id given with the sample.
Now I need to put my own code in the application so that I can load my local database to the server. In order to that I need to add codes at onPerformSync of SyncAdapter. In order to use existing ContentProvider I have the following entries in the manifest file
<uses-permission android:name="com.xylo.pds.RCDataProvider" />. The application which defines the ContentProvider has the following entries -
<provider android:name=".RCDataProvider"
android:authorities="com.xylo.pds.provider"
android:exported="true"
android:readPermission="android.permission.permRead" />
Now if I have added a call to the contentresolver inside SyncAdapter keeping every thing else same just to check things are ok. So that, it is ok, I can change onPerformSync to add codes for uploading data. However now the application stops sysnc the contacts. What I am missing
Please enlighten me. Thanks
1) whats the best mechanism for authentication in such case.
You could/should use OAuth2. either implement your own token on web service website or use common OAuth2 web services in conjunction with the Android Account Manager.
The reason for suggesting this approach is really down to the suggested/recommended way of handling user authentication as per the Google docs.
See "Remembering your user" here http://developer.android.com/training/id-auth/identify.html
Which leads nicely on to your next questions
2) should i take a chunk of data from sqlite table at android, convert to JSON and pass it on to the Webservices for insert/update operation
or take single row and update. Though I think sending single row would
not be efficient.
You should use the android sync adapter which will make use of the account manager functionality described in the link I gave you in answer to question 1
You can code your android service in whatever way you wish but you should be using JSON rather than XML in both directions.
The really neat thing about using the account manager with a sync adapter is that your SQLite content provider methods can use the notifyChange method to tell the sync adapter to update the web service.
You can tell the sync adapter to get the latest data from your web service at the same time or you can schedule syncs.
3) How I manage failure to upgrade remote server. This is easier in case I use single row. My plan is to set status flag for sqlite
records to 1 (default is 0) for records being updated/inserted to
remote server. If update/insert fails I change the status flag back to
0 so that i can use them again next time. In case of success change
the flag to 2.
This is explained by Virgil in the Google I/O video embeded into into this sync adapter tutorial https://sites.google.com/site/andsamples/concept-of-syncadapter-androidcontentabstractthreadedsyncadapter
An alternative solution to using a sync adapter to get the data FROM your web service would be to use GCM (Google Cloud Messaging service. http://developer.android.com/google/gcm/gs.html
Basically Account Manager/sync adapter/gcm is the functionality that Android recommend you use and these are the services that Google uses itself for things like GMail and give your users the ability to keep their data intact even after clearing their data or uninstalling the app and re-installing the app and it also allows for a user to be able to install the app on a new phone and keeping their data.
Hope that helps
UPDATE in response to comments
You should always try hard to minimise traffic and size of data being sent in either direction. I would send the whole lot in one single JSON request gzipped.
Your web server should be able to automatically handle gzipped requests and if gzip is not installed on your server it's simple enough to add
A reference to creating a gzipped output stream from your app can be found here
http://developer.android.com/reference/java/util/zip/GZIPOutputStream.html
For the web server the solution you need will depend on the server you use and you should check with your host about gzip but here are a couple of links for the most popular web servers
Apache - http://howtounix.info/howto/Apache-gzip-compression-with-mod_deflate
NGinx Tutorial - http://www.howtoforge.com/how-to-save-traffic-with-nginxs-httpgzipmodule-debian-squeeze
GZip is the most popular solution for web servers and is very simple to implement.
I don't really have enough info to provide much more advice other than to say that I normally use Ruby on Rails for stuff like this and gzip is handled very simply with the ative support gzip library using something similar to this contacts = ActiveSupport::JSON.decode(gzipped_contacts.gsub("+", ""))
UPDATE 2 notifyChange()
Just to pick up on your point about notifyChange not being appropriate in the content provider due to there being no internet access.
It is fine to use notifyChange() in your content provider as it will tell the sync adapter to update as soon as it is appropriate to do so which means when the device is not too busy and as soon as an internet connection becomes available. That's the whole point of the sync adapter. Should you need to make use of notifyChange in your content provider for other services such as array adapters but you do not want the sync adapter to be told to update then there is a little documented boolean parameter that you can add to the end of the notifyChange params list. set it to false and the content provider will ignore the notifyChange
e.g. instead of the usual getContext().getContentResolver().notifyChange(uri, null);You can use getContext().getContentResolver().notifyChange(uri, null, false);
a) You could ask the users to sign in / sign up from the mobile apps, exactly as you would do it for a web site.
b) Take a look at this http://android-developers.blogspot.ro/2013/01/verifying-back-end-calls-from-android.html
Send more records in the same request, the idea is to make as few requests as possible.
I don't think you should keep the flag for error the same as the default value, it should be a different value so that you will be able to handle it more easily.