Hardware +Resource Manager Overview

Hardware Resource Manager (HWRM) is a client-server solution, which utilizes +ECom plug-ins to achieve device independency. ECom plug-ins convert the client +requests into the hardware control commands.

Purpose

HWRM performs the following functions:

Provide client APIs +to control lights, vibra.
Retrieve battery information +of the device.
Publish certain power-state +related Publish and Subscribe properties.
Enable clients to retrieve +status information on the hardware elements such as light, vibration, power.

Required background

Knowledge of the client-server +architecture, asynchronous processing, and active objects feature of the Symbian +system model architecture.

HWRM architecture

HWRM is made up of the following +components:

Client APIs
HWRM Server

+ Hardware Resource Manager's Architectural Relationships + + +

Client APIs

HWRM provides client APIs that can control +various hardware elements. It also provides callback pointers, so that the +client applications can register to receive notification on the hardware status +changes. Refer to the tutorials for +information on how to use client APIs. Client APIs are useful for both application +developers and the handset manufacturers.

HWRM server

HWRM +server uses plug-in handlers to forward the client API requests to appropriate +plug-ins. The client application communicates with HWRM server through the +client APIs (Light API, Vibra API, and Power API). HWRM server defines the +observer classes, which provide the callback pointers.

The server +calls CHWRMPluginService::ProcessCommandL() function to +forward the client requests to plug-ins. An ongoing ProcessCommandL() is +cancelled by HWRM server using CHWRMPluginService::CancelCommandL(). +The plug-ins process the server's request and pass the response by calling CHWRMPluginCallback::ProcessResponseL() function. +The MHWRMPluginCallback::EventL() method is used to communicate +various events that takes place in the plug-ins.

HWRM uses the central +repository to store the various values and settings such as the light intensity, +duration and delays.

APIs

The HWRM provides the following client APIs +and plug-in APIs:

+ + + + + +Class +Description + + + + +

CHWRMLight

Abstract class defining Lights client API.

+ + +

CHWRMExtendedLight

Abstract class defining Extended Lights client API.

+ + +

CHWRMVibra

Abstract class defining Vibra client API.

+ + +

CHWRMPower

Class defining Power client API.

+ + + +

Typical use cases

HWRM is used for the following:

Used to configure a plug-in.
Start/stop device vibra.
Release the reserved +lights
Retrieve the supported +light targets of the device, current light status, vibra settings and status.
Reserve light targets, +device vibra.
Switch ON/OFF the lights.
Request for tactile +vibration pulse.