The Symbian Connect Object Model
SCOM ( the Symbian Connect Object Model ) is a reusable software component that allows developers to more easily produce applications that incorporate connectivity with Symbian OS smartphones. While SCOM does this by abstracting core connectivity features, it also provides the ability for developers to access other services on the phone which may be developed either by themselves or by a third party.
SCOM is an out-of-process COM server that supports multiple clients. SCOM is not an application that can be directly used by an end-user. Instead, some form of application must be created that uses SCOM in a way that is helpful to the end-user.
Functionality in SCOM and in PC Suites
SCOM does not provide all the functions that a user might expect. It provides functionality to manage device connections and services, and it provides simple access to some core services that Symbian considers should be common to all Symbian OS smartphones.
SCOM was originally created with the needs of smartphone manufacturers in mind. These Symbian licensees have to provide a PC suite to accompany their smartphones. Typically, the suites include the following functionality:
• Backup – copying files that include data, settings and installed applications from the smartphone to the PC
• Restore – restoring the files that include data, settings and installed applications back to the smartphone to restore it to a previous state
• Installation of new software (Symbian OS applications or Java applications)on the smartphone
• Synchronization with PIMs on the PC to keep contacts and calendar data up to date
• Some form of image or sound file management that requires the ability to copy files to and from the smartphone.
What SCOM provides directly
• Backup and restore
• File management
• Software install
PIM synchronization is not directly provided by SCOM. It, instead, allows specialized synchronization software access to services on the Symbian OS smartphone.
It is possible for any developer with sufficient skill and resources to create a complete PC suite based on SCOM, but Symbian does not regard that as sensible. You should assume that the smartphone manufacturers or specialist partners will create their own PC suites and that it will not be sensible to compete directly with them. Instead, developers should focus their attentions on creating applications that complement the PC suites provided with the smartphones.
SCOM and BAL
SCOM is the higher-level API provided to manipulate devices and their filing systems. BAL (the Bearer Abstraction Layer) is a slightly lower-level API that manages device connection and disconnection and services on the device. SCOM uses BAL to provide its own API (take a look at the respective device properties and the mapping will become apparent). It is possible to use SCOM without making direct use of BAL – indeed, this is how SCOM was originally intended to be used. However, the BAL service API is slightly more efficient, in terms of performance, than that of SCOM and so the developer may choose to use BAL for some operations. Figure below gives a simplified view of the components that a PC Connect application interacts with.