 of Table 14.3. In the mobile application, narrow- casting attributes graphical displays are triply encoded-by position (before the "mouth" for mute and select, straddling the "ears" for deafen and attend), symbol ('+' for include & '_' for exclude), and color (green for © 2009 by Taylor & Francis Group, LLC SIP Handbook: Services, Technologies, and Security (a) DoCoMo platform (b) Sample screen FIGURE 14.10 Mobile narrowcasting interface. Isosceles triangles iconfly users. #0 has surged forward and #3 has swayed to the left, but the "ghost icons" show that their local state has not yet been flushed out to the network. #1 has been muted and selected. #2 has been deafened and attended. #3 is in the (currently singleton) selection set, toggled for yawing (spinning). assert & red, yellow, and orange for inhibit-by self, other, and implicitly, respectively). The bridge between the interfaces and the SIP-based backend is a 'read- only' CVE client embedded in the SIP application server. When the policy server is launched, the embedded client connects to a CVE session server and opens a duplex channel for each member in the conference. Every time a user enables or disables one of the narrowcasting attributes, the action is relayed to the embedded CVE client. As each message is received, the client invokes the necessary methods to reflect the changed status in the SIP conference. 14.4.6 System Performance The narrowcasting control is basically lightweight: the commands are typically infrequent, and each of them is easily processed by an application server. For excluding narrowcasting commands (deafen and mute), the time complexity is constant (O(1)), independent of the number of participants in a session. © 2009 by Taylor & Francis Group, LLC Narrowcasting in SIP: Articulated Privacy Control For including narrowcasting commands (select and attend), in which the connectivity state of the complement of the selection needs to be adjusted, the time complexity is O(n), linear in the number of participants. The con- figuration