Android™ Application Development - Bahar Ali Khan

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Chapter 9: Peer-to-Peer Communication 282 // When the service connects, get the default GTalk Session public void onServiceConnected(ComponentName className, IBinder service) { gtalkService = IGTalkService.Stub.asInterface(service); } // If the service disconnects public void onServiceDisconnected(ComponentName className) { gtalkService = null; } }; A bound GTalk Service represents a connection between your application and the GTalk Service APIs. Before you can use the Service to use Android’s Instant Messaging functionality, you need to initiate a new GTalkConnection, as shown in the following section. Making a GTalk Connection and Starting an IM Session A GTalk Connection represents a conduit between the device and a GTalk server. An IM Session is the message pathway used to handle all the instant message traffi c; all the instant messages for a given session fl ow through this pipe. You can create several different connections and multiple IM Sessions connecting to different GTalk servers or IM providers. Under normal circumstances, a device needs a single GTalk Connection supporting a single IM Session that uses the device owner’s username. You can access the default connection and session using getDefaultConnection and getDefaultSession on the GTalk Service and default connection, respectively, as shown in the snippet below: IGTalkConnection gTalkConnection = gtalkService.getDefaultConnection(); IImSession imSession = gTalkConnection.getDefaultImSession(); IM Sessions are used to send text and data messages, set user presence, manage the IM contact roster, and manage group chats. The IM Session is your primary interface for handling instant messaging in Android applications. As a result, the following code snippet shows a more typical implementation of the ServiceConnection used to bind the GTalk Service to an application. It ensures that an IM Session object is always valid. private IGTalkConnection gTalkConnection = null; private IImSession imSession = null; private ServiceConnection gTalkServiceConnection = new ServiceConnection() { // When the service connects, get the default GTalk session. public void onServiceConnected(ComponentName className, IBinder service) { IGTalkService gtalkService = IGTalkService.Stub.asInterface(service); try { gTalkConnection = gtalkService.getDefaultConnection(); imSession = gTalkConnection.getDefaultImSession(); } catch (RemoteException e) { }
} Chapter 9: Peer-to-Peer Communication // When the service disconnects, clear the GTalk session. public void onServiceDisconnected(ComponentName className) { gTalkConnection = null; imSession = null; } }; Introducing Presence and the Contact Roster Presence is a lightweight mechanism used in instant messaging to broadcast a user’s availability. Originally, presence was represented as a simple fl ag that indicated when a user was logged on and available to chat. This has gradually evolved into a more detailed status indicator that lets users describe their availability more accurately by indicating if they’re available, busy, away from the computer, or offl ine. The recent popularity of applications like FriendFeed and Twitter has resulted in presence being expanded to include custom messages that can describe anything from a user’s current activity to the music they’re listening to. Users can see the presence of all the people in their contact roster. The contact roster is a list of all the contacts with whom a user has an agreement to exchange messages and share presence information. When adding someone to their roster, users are implicitly subscribing to updates of that person’s presence, and changes to their own presence are propagated to all the contacts on their roster. Instant messaging is an inherently portable technology — a user’s presence and contact roster are maintained by the GTalk server, so the roster on an Android device is synchronized with Gmail chat and any desktop IM clients. Managing the Contact Roster Developers can access the contact roster to determine the presence of any of a user’s IM contacts, monitor presence updates, add new contacts, remove existing ones, and handle subscription requests. Accessing the IM Contact Roster When it's made available, the contact roster should be accessible through a native Content Provider using the helper class android.provider.Im.Contacts. You can query it as you would any other Content Provider. In the following snippet, you can see how to iterate over the roster to fi nd the presence of each IM contact: Uri uri = android.provider.Im.Contacts.CONTENT_URI_CHAT_CONTACTS; Cursor c = managedQuery(uri, null, null, null); if (c.moveToFirst()) { do { String username = c.getString(c.getColumnIndexOrThrow(Contacts.USERNAME)); int presence = c.getInt(c.getColumnIndexOrThrow(Contacts.PRESENCE_STATUS)); if (presence == Contacts.AVAILABLE) { 283
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Professional Android Application su
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Professional Android Application D
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Professional Android Application D
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About the Author Originally from Pe
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Acknowledgments A big thank you goe
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Contents Chapter 2: Getting Started
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Contents xii Saving and Loading Fil
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Contents Chapter 10: Accessing Andr
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Introduction Now is an exciting tim
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Introduction covered, you can move
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Introduction At http://p2p.wrox.com
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Chapter 1: Hello, Android 2 Using t
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Chapter 1: Hello, Android An Open P
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Chapter 1: Hello, Android 6 ❑ ❑
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Chapter 1: Hello, Android 8 When ma
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Chapter 1: Hello, Android 10 In mar
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Chapter 1: Hello, Android 12 Each A
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Chapter 1: Hello, Android 14 ❑ Da
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Chapter 1: Hello, Android 16 ❑ an
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Getting Started All you need to sta
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Chapter 2: Getting Started Unless o
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Installing the ADT Plug-in Install
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Chapter 2: Getting Started 3. In th
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Chapter 2: Getting Started If every
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} lp = new LinearLayout.LayoutParam
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❑ ❑ ❑ ❑ ❑ Small screens w
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Chapter 2: Getting Started on how t
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Chapter 2: Getting Started To start
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Ensuring a Seamless User Experience
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Figure 2-11 Chapter 2: Getting Star
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} myListView.setAdapter(aa); Chapte
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Chapter 2: Getting Started A number
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Creating Applications and Activitie
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Chapter 3: Creating Applications an
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Creating Resources Chapter 3: Creat
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❑ ❑ #ARGB #ARRGGBB Chapter 3: C
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android:startOffset=”500” andro
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Referencing Resources in Resources
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} } Chapter 3: Creating Application
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Chapter 4: Creating User Interfaces
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Chapter 5: Intents, Broadcast Recei
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Data Storage, Retrieval, and Sharin
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Chapter 6: Data Storage, Retrieval,
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} Chapter 6: Data Storage, Retrieva
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} } } Chapter 6: Data Storage, Retr
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Querying Your Database Chapter 6: D
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} // Open or create the database to
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Adding, Updating, and Deleting Cont
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} } Chapter 6: Data Storage, Retrie
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} } break; Chapter 6: Data Storage,
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Maps, Geocoding, and Location-Based
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Chapter 7: Maps, Geocoding, and Loc
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} Chapter 7: Maps, Geocoding, and L
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Chapter 11: Advanced Android Develo
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400 Android, getting started Androi
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402 databases databases creating ea
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404 interapplication communication
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406 passing custom class objects pa
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408 synchronizing threads synchroni
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Programmer to Programmer Get more
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Android™ Application Development - Bahar Ali Khan

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