I am working on an android fitness app and I want to get the hang of using ContentProviders. I was thinking about using the myfitnesspal api to get a list of exercises, but the api is private and my request has not been addressed yet. Then I considered scraping exercises from a website--but I am a little concerned about the reliability of this approach (if the site goes down, app won't keep working).
What is the best way to go about this? Is it "safe" to get information from a website (rather than an api) with a ContentProvider?
Correct me If I am wrong. You want user to acces your data even if there is not web API active. So my thought for it would be
Download all the data from web API and store it in database
create an node to check if data has been updated in the API if updated download new data in background and update the database else show same data from database
Benefits
User don't need to download data all the time they use app and their volume of internet would be saved
User don't need to see blank page if there's not any data
If im wrong, i would really like to know.. but the answer is simple: a ContentProvider allows only the connection to a database in your cellphone. You can't use a ContentProvider to get data from the internet. What you're trying to do is achievable with a WebService, which is an application running on a determined domain on the Internet and allows you to call some pre-defined methods linked to URLs of this same domain (but i imagine you know about that, right?).
Related
I'm building a listview and getting it's data from Parse.com. At the moment, every time the app loads up it queries for new data from Parse.com, causing the whole listview to load.
I'd like a situation where the listview references a local datasource and only go to Parse.com if new data is available. Somewhat similar to what the instagram app does whereby when you load it up, the list view is already populated and would get updated if needed.
I have tried ParseQuery Cache policies but the behavior still stays the same. What would be the most efficient way of implementing this feature?
Thanks in advance.
Sync Adapters can help you with your your problem. It is generally used for account and cloud synchronization. But there is no limitation using it.
http://developer.android.com/training/sync-adapters/index.html
Synchronizing data between an Android device and web servers can make
your application significantly more useful and compelling for your
users. For example, transferring data to a web server makes a useful
backup, and transferring data from a server makes it available to the
user even when the device is offline. In some cases, users may find it
easier to enter and edit their data in a web interface and then have
that data available on their device, or they may want to collect data
over time and then upload it to a central storage area.
Although you can design your own system for doing data transfers in
your app, you should consider using Android's sync adapter framework.
This framework helps manage and automate data transfers, and
coordinates synchronization operations across different apps. When you
use this framework, you can take advantage of several features that
aren't available to data transfer schemes you design yourself
You can access sample project here: http://developer.android.com/shareables/training/BasicSyncAdapter.zip
Note: Sync adapters run asynchronously, so you should use them with the
expectation that they transfer data regularly and efficiently, but not
instantaneously. If you need to do real-time data transfer, you should
do it in an AsyncTask or an IntentService.
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.
I'm doing a photosharing app with account authentication using phonegap.
We will be using jquery(client),CSS3(no-images and animation)/codeigniter(server) and we already structure our database from the server.
I can't decide how should I retrieve my data and what to do with it after I pull it from the server.
I should retrieve the data base from the login that is used it pulls out the friends/followers/people who comment to the pictures just like instagram did but it is more like a combination of facebook and instagram.
The data should be synchronized or auto update everytime there's a new comment from the photos,friend request,etc,.
Should I cache the data when I pull it from the server?What is the best way to CRUD cache data?
Generally, you can prefetch some amount of necessary data when the user log in, and you can have a background service to schedule batch transfers and batch update data. It should not automatically sync data everytime (unless you really need it), because internet connections will shorten the battery life rather quickly.
You can read this good document about this: http://developer.android.com/training/efficient-downloads/efficient-network-access.html#PrefetchData
The document is for Android, but I think it can be applied for other platforms.
Hope it help you something :)
I'm developing an Android app as a "proof of concept" for our company. If they like it and think it's worth investing, then we'll move on to bigger things. I'm trying to figure out the best/most practical approach for this.....the basics of the app will connect to our DB and display information regarding a specific customer. For now, let's say we will only pull data from 3-4 tables (but there could be 10+ in the future). If the app doesn't have an internet connection then it should use the local DB. What is the best approach for this? Here's what I was thinking and would like some input/suggestions if possible:
1.) app runs checks internet connection. If exists, check db version (how, through a web service?)..if server db is newer, get latest data. If no internet, use local db.
2.) app parses data and displays it.
If this is correct, then there could be no modifications to the web service that would add fields to a result without changing the app as well. Is there a way for an app to parse fields regardless of how many fields there are?
I've read and walked through the tutorial on google with databases and such (Notepad tutorial) but it seems like the column names are all hard-coded in the parsing class, which I was hoping to avoid.
Sorry if this is confusing but I know I need my app to use a local db to read data, I also know that the app must get data from the server when it can (via onCreate or a refresh button) and copy it locally....Copying it locally is the part I'm having trouble understanding I guess....is there no way of saying "go out and get this result and display it", knowing that those results could mean 5 fields the first time or 1 the next.
Any help/guidance is greatly appreciated!
You probably want to use a SQLLite DB to store your data locally, a ContentProvider to provide CRUD access to the db, and a SyncAdapter to sync with your server when possible. The Sync Adapter also writes to the DB via the ContentProvider. See the SampleSyncAdapter sample in the SDK for an example of how this works. You will be implementing your own ContentProvider, but the sample just uses Android's supplied Contacts ContentProvider.
http://developer.android.com/resources/samples/SampleSyncAdapter/index.html
I am trying to decide on what data storage methods to implement. Here is the situation. Whatever method I choose, it is going to be updated once week (can I update a SQLite db without putting out an update in the market?). The user cannot add or remove items from this ListActivity, they can only pick the ones they want. This data method should be able to remember the selected items during any given week. Let me know what method you would use and why. Thanks so much in advance.
A webservice would allow you to update the data whenever you want without having to push updates to the market. And updating your app in the market doesn't guarantee that users will apply the update. Ofcourse the downside here is that your users would need to be connected to the internet while using the app.
Moving your database to remote server will give you freedom to manipulate data without actual application being updated, thus no need to update on the market. If it is a matter of access to internet, you can still use this practice, just more work has to be done (adding Broadcasters that will listen to connectivity than update the local database with global one on your server, or something similar).
If you want to update the data on the device once a week, then you will need to use the local SQLite database and interact with a web service that provides the updates. You will not need to go through the market to do this. However, if you need to update the structure of the database (add, remove, or change columns or tables for example), then you will need to update your app on the market.
I highly recommend watching the Google IO 2010 talk Developing Android REST client applications. The speaker is the author original author of the Twitter app for Android, and talks about the design patterns and best practices that he uses.