Largely as a result of security concerns, developer access to the GTalk IM Service has been restricted for Android SDK version 1.0. As a result, the functionality described in this section will not be available to developers using the first full release of the Android SDK.

Rather than remove the affected sections, they have been left here in full as a guide for use with future Android releases.

Later releases of Android will expose a full suite of instant messaging functionality through an XMPP based IM Service. This will include management of contact rosters, presence notification, and the trans-mission and receipt of instant messages.

Google Talk (GTalk) is an instant messaging protocol for peer-to-peer (P2P) communication. Once con-nected, GTalk maintains a persistent socket connection with the GTalk server, meaning fast response times and low latency.

This section is based on an early SDK implementation that used GTalk. GTalk is based on the XMPP protocol, but it’s a Google-specific variant that currently requires that users have a Gmail account.

What makes the GTalk Service particularly interesting for developers is the ability to broadcast Intents over the air (OTA) between Android devices using data messaging. Data messages received by a remote device are re-broadcast as Intents locally, meaning that this mechanism lets you broadcast an Intent on a remote device.

The GTalk Service can be used to create your own multi-user, social, or collaborative applications. It provides the framework for building a range of applications, including distributed emergency warning systems, dynamic route guidance applications, family social networks, and augmented reality gaming systems.

Android will eventually include all the interfaces needed to create a Google Talk Instant Messaging cli-ent, including full control over presence management and subscription handling. You can, if you’re so inclined, build a replacement for the native client — or simply use the relevant components within your own applications.