SyncTab architecture. Part 2. Android Application

This post is a continuation for recent post with description of SyncTab server application. In this post I'm going to tell about SyncTab Android application.

As android application is very simple, I will make a very short description.

SyncTab application has a few activities only: the main activity is a list of shared links. When user first opens an application, she can either login into or register a new account. There is also a way to reset a password. User can only reset password, as original password is not stored; only salted hash of the password is stored on server. After user is signed in, she can see the list of links, edit settings and tags etc.

When user is authenticated and device is online, application starts two services: SyncService and RefreshService.

RefreshService connects to the server and checks if there are any new links to open on this device. Each device has an associated tag and opens only links with specified tag. Android device by default checks for the links with Android tag, and opens them if any. By default, RefreshService checks the server every minute if connection is up. But it is possible to change a period time or disable this service at all (if user doesn't want to receive links on device).

SyncService is used to synchronize android application status with server. Application allows to send links, when device is offline. In this case, link can't be send, but is added to the sync queue. Well, there are other operations that can be proceeded offline, like logout, remove link, re-send link, add/edit/remove tags. If device is offline, such operations are added to the sync queue. When network is app and device is online, SyncService checks the sync queue and executes each task in it. Sync queue tasks are persistent and stored in the database.

No hard coded values, except preferences names. Everything moved to the appropriate files like strings.xml, array.xml, integers.xml, colors.xml etc. Values vary not only for different localization, but for different devices (e.g. phone and tablet).

Documentation is available only online from synctab website. Website has two versions: for normal clients and for mobile clients. While, my phone will be redirected to the mobile version, a tablet will open a normal version of website.

There are two managers for each entity, a regular manager and remote manager. Application works mostly with regular manager, which itself calls remote manager if need. For example, there are TagManager and RemoteTagManager. To call an operation, activities use SyncTabFacade, while SyncTabFacade calls managers.

Activities started using special IntentHelper class, that provides a static functions like showLoginActivity(), showAboutActivity(), browseDocumentation() etc.

Links' favicons are cached as files in the cache directory. When a list of new links is retrieved, a favicon preloader thread starts. Thus, favicons are downloaded in background. If device is offline, and favicons can't be loaded, than an appropriate task is added to the sync queue for each favicon (and next time device is online, the favicons will be downloaded).

Well, looks like nothing interesting I can tell more about SyncTab android application.

So I decided to write a list of helpful facts about developing for Android as a separate post – "Tips: developing for Android".