The Symbian OS (779886), страница 55
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The Bluetooth standard therefore includes security protocols (which Symbian OSimplements).As well as conventional serial communications, over a physical seriallink or virtualized over IrDA or Bluetooth, Symbian OS supports a numberof higher-level short-link services:• Higher-level IrDA protocols are supported, for example includingIrTranP for beaming camera images.• IrDA Object Exchange (OBEX), a binary protocol for data exchange,is supported over IrDA, Bluetooth and USB connections.SHORT-LINK SERVICES247• A number of Bluetooth profiles including security profiles are supported, with support for licensee extension.• USB device management is supported.ArchitectureWhile short-link services forms a natural logical and functional block, itdoes not form a cohesive architectural unit.
While the supported shortlink technologies are designed to interoperate extensively and implementthe overall architectural patterns of communications services (server- andframework-based, protocol module plug-ins to the Socket Server, serialport plug-in implementations to the Serial Server framework), the detailedarchitecture of each is distinct and should be understood independentlyof the serial architecture.IrDA is implemented as a Socket Server plug-in module, loaded bythe Socket Server when an IrDA socket is requested (either directly byan application, or by other components in the Comms Services). Withinthe Socket Server session, the protocol module communicates with theinfrared port through the Serial Server and its IrDA serial plug-in CSYmodule, which ultimately drives the logical and physical device driversfor the onboard infrared hardware.The OBEX implementation is designed as a wrapper for either asocket style API (RSocket for IrDA and Bluetooth) or a USB client API(RDevUsbcClient for USB).
OBEX is implemented as a static DLL to whichclients link at compile time, with the OBEX code running in the clientthread.Bluetooth is implemented as a Socket Server protocol plug-in module.Clients request a Bluetooth socket from a Socket Server session. TheBluetooth socket communicates with the firmware controller via theBluetooth HCI implementation. Symbian OS implements the mandatedv1.2 Bluetooth stack.IrDA and OBEXSymbian OS has supported IrDA since the first ER5 release, providingline-of-sight infrared data exchange between devices.
IrDA is more thana simple connection protocol and, in fact, comprises a complete set ofprotocols from application level to link level, including IrTranP (Infra RedTransfer Picture, for devices with cameras), IrCOMM (IrDA serial portemulation) and TinyTP (TinyTransfer Protocol, providing flow control),as well as lower-level protocols including FIR (Fast Infrared). All aresupported by Symbian OS.IrDA also provides the underlying support for OBEX over infrared(Infrared Object Exchange, IrOBEX). OBEX is a protocol and not a servicebut application-level services can be created that use the protocol to248THE COMMS SERVICES BLOCKsend and receive data.
At the application level, Symbian OS providesOBEX-based services including SendAs messaging, SyncML data synchronization, installer services, and so on. Symbian OS has supported OBEXsince the first ER5 release. Since the introduction of Bluetooth supportin Symbian OS v6, it has supported OBEX over Bluetooth and, sinceSymbian OS v7, OBEX over USB (but with server functionality only).BluetoothBluetooth also defines a complete protocol stack and not just a radiolink technology.
The Bluetooth services that run on top of the stack aredefined as Bluetooth profiles. Symbian OS provides Serial Port, PAN(Personal Area Networking) and Generic Access profiles, as well asRemote Control (since Symbian OS v9), that enables a Symbian device tocontrol Bluetooth peripherals, for example headsets. Licensees may addadditional profile support.Bluetooth components include:• The Bluetooth Manager is the information store (implemented overSymbian OS DBMS) used to manage details of local and remoteBluetooth devices.• Bluetooth SDP (Service Discovery Protocol) enables Bluetooth devicesto find each other and store information about discovered devices.(The SDP database is not persistent.)• The Bluetooth HCI (Host Controller Interface) interfaces the Bluetoothstack to the onboard controller hardware and is provided as a referenceplug-in.Symbian OS has supported Bluetooth since Symbian OS v6, withincremental support added over subsequent releases.USB Manager and ClassesUSB classes are analogous to Bluetooth profiles and represent the usecases that a device supports when it connects to a USB host.
TheUSB Manager on a device enumerates, starts and stops the USB classesimplemented on the device and provides a query interface for their status,providing a central control point and an on–off switch.Symbian OS provides a USB Manager and implements USB CSY (serialover USB), Mass Storage and OBEX (OBEX over USB) classes. The USBManager implements a server interface for USB class implementations andfor clients requesting information or services from USB classes (typicallythe user is the USB host) and provides the underlying mechanism forapplication-level class configuration and querying of the USB host (theother connected device) across a USB connection.SHORT-LINK SERVICES249Component CollectionsOBEX CollectionThis collection defines the OBEX (Object Exchange) session protocol.OBEX is a binary protocol and is therefore compact and can supportapplication-level services from simple beaming of vCard and vCal entriesto full-scale synchronization, for example, as a SyncML bearer.Table 9.20 OBEX ComponentsComponent NameDevelopment NameOBEX ProtocolOBEX, IROBEXOBEX Extension APIOBEX EXTENSIONAPISIn Symbian OS, OBEX is supported over IrDA infrared, Bluetooth andUSB, providing session-style APIs, that is, Connect and Disconnect andbasic Get and Put commands.
See Figure 9.33.OBEXOBEXProtocolOBEXExtension APIFigure 9.33 OBEX componentsUSB ManagerThis collection comprises the manager for the USB classes presenton a device, for example providing the mechanism beneath a configuration application like a control panel to switch on and off theavailable USB classes on a Symbian OS device and to query a USB host(not a Symbian OS device) application across a USB connection. SeeFigure 9.34.USBManagerUSBMgr.Figure 9.34 USB Manager components250THE COMMS SERVICES BLOCKTable 9.21 USB Manager ComponentsComponent NameDevelopment NameUSB ManagerUSBShort Link CollectionThese higher-level components support the Bluetooth protocol implementation and Bluetooth profiles.
See Figure 9.35.Short LinkBtooth.Protocol Btooth.Mgr.ClientAPIsBtooth.SDPBtooth.ProfilesHCIFrmwk.RemoteControlFrmwk.Figure 9.35 Short Link componentsTable 9.22 Short Link ComponentsComponent NameDevelopment NameBluetooth Protocol Client APIsNo unitBluetooth ManagerBLUETOOTHMANAGER,BLUETOOTHBTEXTNOTIFIERS,BLUETOOTHCONFIG,BLUETOOTHGAVDP,BLUETOOTHROM,BLUETOOTHUSERBluetooth SDPBLUETOOTHSDPBluetooth ProfilesBLUETOOTHAVRCPRemote Control FrameworkBLUETOOTHREMOTECONTROLHCI FrameworkBLUETOOTHHCI• The Bluetooth Protocol Client APIs are used by Bluetooth socket clientsand provide support for low-level control of protocol parameters(packet sizes, for example) and hardware (power modes, for example).• The Bluetooth Manager provides an information store for managingdetails of the local and remote Bluetooth devices, implemented overSymbian OS DBMS, allowing entries to be stored, retrieved, modifiedand deleted.SHORT-LINK SERVICES251• The Bluetooth Service Discovery Protocol (SDP) is the mechanismused by connected Bluetooth devices to query each other andexchange information about the Bluetooth services they support.• The Bluetooth Profiles include Generic Access Profile (GAP), PersonalArea Networking (PAN), since Symbian OS v8, and (from SymbianOS v9) Audio and Video Remote Control (AVRCP).• The Remote Control Framework enables sending and receiving ofremote-control commands to and from remote Bluetooth devices.
(Itis supported from Symbian OS v9.)• The HCI Framework is a reference implementation of the BluetoothHost Controller Interface as used by the Bluetooth Stack to interface tothe onboard controller hardware. It provides a full range of HCI commands, accessed indirectly via L2CAP and RFComm layers. Licenseescan replace the supplied implementation.Short Link Protocol Plug-insThis collection implements the Bluetooth core stack, including the Bluetooth protocols and the HCI firmware implementation and the IrDAprotocol suite as PRT Socket Server plug-in-in protocol modules.
SeeFigure 9.36.Table 9.23 Short Link Protocol Plug-insComponent NameDevelopment NameBluetooth Stack PRTBLUETOOTHSTACKBluetooth HCIBLUETOOTHHCIPROXYIrDA PRTIRDA, INFRA-REDCONFIG• The Bluetooth Stack PRT component implements the Bluetooth stackas a Socket Server protocol plug-in, providing a complete implementation including L2CAP, RFCOMM and SDP.• The Bluetooth HCI is a reference implementation of firmware-specificsupport for the standard Bluetooth Host Controller Interface (theShort Link ProtocolPluginsBtooth.StackPRTBtooth.HCIIrDAPRTFigure 9.36 Short Link Protocol Plug-ins252THE COMMS SERVICES BLOCKstack-side implementation of the interface forms part of the standardBluetooth support provided by Symbian OS).• The IrDA PRT is an implementation of the IrDA protocol stack as aSocket Server protocol plug-in, provides a complete IrDA implementation including IrTranP (for sending pictures) and FIR (Fast Infrared).Serial Comms Server Plug-ins CollectionCSY modules are implementations of serial ports virtualized over differentbearers (RS232, USB, Bluetooth, IrDA) and are loaded by the C32 SerialServer in response to clients to provide ports of the types requested.
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