System Introspection for System Analysis on Mobile Devices

Figure 4.4: Life-cycle of an android activity - Each activity is initializedby calling the onCreate() method. Inactive activitiesare placed in the background of the operation system[From the Android Developer Guide]A client connects and opens a stream to a server and the server opens a streamback to that client. Once connected the server sends the rooster to the client.The rooster contains all other clients known to the client. When the rooster isloaded, the online presence is delivered to all clients of the rooster. Each clientreturns its own presence. Whenever a message is send to another client, themessage is send to the server which then <strong>for</strong>wards the message to the recipient.If the recipient is not in the domain of the server, the server negotiates a serverto-serverconnection to the recipients server which delivers the message to itsclient. Figure 4.5 shows a typical message session containing elements fromconnecting to a server and exchanging messages.This work uses the message stanza <strong>for</strong> data exchange between the probe andthe client (see chapter 6.1). The data exchanged is primarily using simpledata structures. Most of the data can be packed into an XML structure and17