Introduction

This section describes the key concepts of the system model and the system definition file.

The system definition file is an XML file which contains the system model architecture and build information. The System Model Manager (SMM) uses the file to generate the system model diagram. Licensees can modify the file to reflect their changes in the system model.

Key concepts

System model

The system model is a hierarchical representation of the Symbian platform architecture. It is a hierarchy of Symbian platform architectural levels, layers, blocks, sub-blocks, collections and components.

System definition file

The system definition file is an XML file, which describes the layers, blocks, sub-blocks, collections, and components that constitute the system model. It provides information about the Symbian platform architecture which is used to build the system and generate a system model diagram.

Module

The term module is used to refer to a block or a sub-block. If a block has sub-blocks, the sub-blocks are modules. If a block does not have sub-blocks, the block is a module.

CBR

CBR stands for Component Based Release. The CBR mechanism packages and delivers Symbian platform in a modular way. Licensees and partners can use this modularity to integrate and build components on the platform.

How the system model maps to the system definition file

The system definition file describes the Symbian platform system model. The following screenshot is a scaled down view of a system model diagram for Symbian OS v9.5.

System model diagram


System model diagram

The following table summarises the mapping information between the system model and the system definition file. For more information about the elements in the system definition file, refer to System Definition File Elements.

System Model

System definition File

Definition

Examples in Symbian platform

layer

<layer>

The highest level and a fundamental representation of Symbian platform.

A layer contains blocks or collections.

Kernel Services and OS Servicesare layers.

block (optional)

<block> (optional)

Represents a different technology division within a particular Symbian platform layer.

A block contains sub-blocks or collections.

PIM and Messagingare modules of the Application Services layer.

sub-block (optional)

<subblock>(optional)

Represents a tightly coupled subdivision with a technology.

A sub-block contains collections.

Communications Framework and Cellular Baseband Services are the sub-blocks of the Comms Services block. The Comms Services block belongs to the OS Services layer.

collection

<collection>

Represents a logical group of components, coupled by function, for example, a client/server, or coupled by usage, for example, a family of plug-ins.

A collection contains components.

PIM Protocol and PIM Application Services are collections within the PIM module.

component

<component>

The smallest architectural unit that appears in the System Model. It maps to a single bld.inf file or a CBR package.

Note:A system definition file with no components cannot be used by the SMM to draw the system model diagram.

Calendar and Contacts Model are components of the PIM Application Services collection.

unit

<unit>

The build details of a component. The build details comprise an MRP file and/or a bld.inf file. A number of alternative units may be listed for each component.

Note: Unit elements are not used by the SMM.

For the Calendar component, the build directory is common/generic/app-engines/calendar/group, and the MRP file is common/generic/app-engines/calendar/group/app-engines_calendar.mrp.