symbian application development concepts

8/14/2019 Symbian Application Development Concepts

1/28

Symbian:Symbian:Application DevelopmentApplication Development

ConceptsConcepts


2/28

Application ComponentsApplication Components

ApplicationApplication

DocumentDocument

AppUIAppUI ViewView

ContainerContainer


3/28

Application Components:Application Components:

Application ClassApplication Class

Entry Point for Symbian OperatingEntry Point for Symbian OperatingSystemSystem

Contains Application Unique IdentifierContains Application Unique Identifier

(UID)(UID)

Development UID automatically assigned byCarbide C++

Get UIDs for Public Applications athttp://www.symbiansigned.com/

Responsible for Creation of DocumentResponsible for Creation of Document


4/28


Document ClassDocument Class

Manages Application Data ModelManages Application Data Model

Responsible for Creation of AppUI ClassResponsible for Creation of AppUI Class

ObjectObject


5/28


AppUI ClassAppUI Class

Not a Visual Class i.e. its Objects are NotNot a Visual Class i.e. its Objects are NotVisibleVisible

Serves as Controller for the ApplicationServes as Controller for the Application

Manages Views (Container)Manages Views (Container)

Responsible for Application Wide EventResponsible for Application Wide EventHandlingHandling


6/28


View ClassView Class

Provide Screens for the ApplicationProvide Screens for the Application

View Specific Command HandlingView Specific Command Handling

View Has a Unique IDView Has a Unique ID A View Can be Activated fromA View Can be Activated from Within the Same Application orWithin the Same Application or

From Another Application by Providing UID ofFrom Another Application by Providing UID of

the Application and ID of the Viewthe Application and ID of the View


7/28


Container ClassContainer Class

Responsible for Handling UI ComponentsResponsible for Handling UI Components

A li ti St t O i i


8/28

Application Structure Overview inpp ca on ruc ure verv ew nS60S60

CApaApplication CApaDocument CCoeAppUi CCoeControl

CEikApplication CEikDocument CEikAppUi

CAknApplication CAknDocument CAknAppUi

CAknAppUiBase

CAknView

CAknViewAppUi

CExpApplication CExpDocument CExpAppUi CExpView CExpContaine

SymbianOS

Series60

ExpApp


9/28

Symbian Data TypesSymbian Data Types

TCharchar

VoidvoidTAny*void*

TBoolboolean

TReal64double

TReal32float

TUintunsigned int

TIntint

Symbian OSStandard C++


10/28

Symbian ClassesSymbian Classes

Class NamesClass Names Prefix+Class Name+SuffixPrefix+Class Name+Suffix

C Classes (C is Prefix in Class Name)C Classes (C is Prefix in Class Name) Derived Directly or Indirectly from CBaseDerived Directly or Indirectly from CBase

Constructed on Heap and Require CleanupConstructed on Heap and Require Cleanup

T Classes (T is Prefix in Class Name)T Classes (T is Prefix in Class Name) Also Called Data Type ClassesAlso Called Data Type Classes

Encapsulates a Value of Specific Type e.g. TCharEncapsulates a Value of Specific Type e.g. TChar Generally Do Not Use Dynamic Data i.e. Created on Stack but MayGenerally Do Not Use Dynamic Data i.e. Created on Stack but Mayalso Use Heap if Requiredalso Use Heap if Required


11/28

Symbian ClassesSymbian Classes

R Classes (R is Prefix in Class Name)R Classes (R is Prefix in Class Name) Also Called Resource ClassesAlso Called Resource Classes Owns a Resource HandleOwns a Resource Handle Can be Instantiated on Heap or StackCan be Instantiated on Heap or Stack

M Classes (M is Prefix in Class Name)M Classes (M is Prefix in Class Name) Also Called Interface ClassesAlso Called Interface Classes Equivalent to an Abstract Interface (Contains Pure Virtual Functions)Equivalent to an Abstract Interface (Contains Pure Virtual Functions) Used to Define Callback InterfacesUsed to Define Callback Interfaces

Static Classes (No Prefix Attached to Static Classes)Static Classes (No Prefix Attached to Static Classes) Contains Only Static FunctionsContains Only Static Functions Cannot be Instantiated into an ObjectCannot be Instantiated into an Object


12/28

Exception HandlingException Handling

Standard C++ Exception Handling inStandard C++ Exception Handling inSymbian OS v9 (try/catch mechanism)Symbian OS v9 (try/catch mechanism)

Lightweight Exceptions for PreviousLightweight Exceptions for PreviousSymbian OS (before OS v9)Symbian OS (before OS v9)

Leaves are Alternative to C++ ExceptionsLeaves are Alternative to C++ Exceptions

Leaves are Lightweight Exception HandlingLeaves are Lightweight Exception Handling

MechanismMechanism


13/28

Exception Handling: LeavesException Handling: Leaves

A LeaveA Leave Suspends Code Execution at the Point where Leave OccursSuspends Code Execution at the Point where Leave Occurs

Resumes Execution where Leave is TrappedResumes Execution where Leave is Trapped

Leaves May Occur while Performing Operations thatLeaves May Occur while Performing Operations that

May not SucceedMay not Succeed Allocation of MemoryAllocation of Memory

File CreationFile Creation

Traps are used to Catch Leaves and Allow them to beTraps are used to Catch Leaves and Allow them to beHandledHandled

Functions that May Leave have L as Suffix in theirFunctions that May Leave have L as Suffix in theirNameName

Panics Cannot be Caught and HandledPanics Cannot be Caught and Handled


14/28

Cleanup StackCleanup Stack

The cleanup stack is used to storepointers that may become orphaned if aleave occurs

Push Pointer to Objects on Cleanup Stacks

In case of a Leave, All Objects whosePointers are Pushed on Cleanup Stack will beProperly Destroyed


15/28

Two Phase Construction ofTwo Phase Construction of

ObjectsObjects

1.1. Make All Constructors Private or Protected.Make All Constructors Private or Protected.

2.2. Provide Static Factory Function(s) to CreateProvide Static Factory Function(s) to CreateObjects e.g.Objects e.g.

NewL()NewL() NewLC()NewLC()

Code that May Leave is Placed in FactoryCode that May Leave is Placed in FactoryMethodsMethods

No Code within a Constructor Should EverNo Code within a Constructor Should Ever

Leave.Leave.


16/28

DescriptorsDescriptors

Strings in Symbian OS are CalledStrings in Symbian OS are CalledDescriptorsDescriptors

May Contain Text and Binary DataMay Contain Text and Binary Data

TPtr88 bit CharactersNarrowTPtr88 bit CharactersNarrowDescriptorsDescriptors

TPtr1616 bit CharactersWideTPtr1616 bit CharactersWideDescriptorsDescriptors

Descriptors Can beDescriptors Can be Constant (Contents are Constant)Constant (Contents are Constant)


17/28

Pointer DescriptorsPointer Descriptors

Can Point to Text on the Heap, Stack orCan Point to Text on the Heap, Stack orROMROM

Constant: TPtrConstant: TPtrCC

Modifiable: TPtrModifiable: TPtr

0x1234566 !OLLEH

0x234567

10

6

!OLLEH

Length Pointer

Length

Max

Length


18/28

Buffer DescriptorsBuffer Descriptors

Stack Based, Useful for Relatively SmallStack Based, Useful for Relatively SmallStringsStrings

Directly Contain the StringDirectly Contain the String Constant: TBufConstant: TBufCC

Modifiable: TBufModifiable: TBuf

!OLLEH6

!OLLEH86

Length

LengthMax


19/28

Dynamic Descriptors (HeapDynamic Descriptors (Heap

Based)Based)

Can be Used for StringsCan be Used for Strings That are Too Big to be Placed on StackThat are Too Big to be Placed on Stack

For Which Size is Not Known at CompileFor Which Size is Not Known at Compile

TimeTime Constant: HBufConstant: HBufCC

!OLLEH6

Heap

0x345678


20/28

Dynamic Descriptors (HeapDynamic Descriptors (Heap

Based)Based)

RBuf is Modifiable and DynamicallyRBuf is Modifiable and DynamicallyAllocated DescriptorAllocated Descriptor


21/28

Threading and Active ObjectsThreading and Active Objects

Symbian Allows Application Programs toSymbian Allows Application Programs toCreate ThreadsCreate Threads

However, Recommendation is to UseHowever, Recommendation is to UseActive Objects where PossibleActive Objects where Possible

Alternative to Threads and PreferredAlternative to Threads and PreferredOption is UsingOption is Using

Asynchronous Functions along with ActiveAsynchronous Functions along with ActiveObjectsObjects


22/28

Active Object FrameworkActive Object Framework

Active Object FrameworkActive Object Framework Active ObjectsActive Objects

Active SchedulerActive Scheduler

Active Object Framework is Used forActive Object Framework is Used forEvent Driven MultitaskingEvent Driven Multitasking


23/28

Active ObjectActive Object

An Active Object:An Active Object: Requests an Asynchronous Service and

Handles the Resulting Completion of Event

Sometime After the Request.

May Ask to Cancel a Request

Is Listed with Active Scheduler


24/28

Active SchedulerActive Scheduler

When Asynchronous Service Completes,It Generates Events

Active Scheduler Detects Events

Determines Associated Active Object

Calls the Active Object to Handle the Event.


25/28

Submitting an AsynchronousSubmitting an Asynchronous

RequestRequest

Each Active Object Can Only Have OneOutstanding Request

Check for previous outstanding requests. If aRequest has Already been Placed, the Codemay Panic

Refuse

Cancel Outstanding Request and Submit New One

Issue the Request Mark Active Object as Waiting


26/28

Active Object Event HandlingActive Object Event Handling

Active Object Implements the Event Handling FunctionActive Object Implements the Event Handling Function Active Object Event Handler is the Function forActive Object Event Handler is the Function for

Handling Completion of Asynchronous CallHandling Completion of Asynchronous Call

Active Object Handler is Not Pre-EmptedActive Object Handler is Not Pre-Empted

Control Returns to the Active Scheduler When EventControl Returns to the Active Scheduler When EventHandler ReturnsHandler Returns

If multiple events have occurred before control returnsto the scheduler, they are handled sequentially inorder of their Priority

Active Scheduler Calls the Event Handling Function ofActive Scheduler Calls the Event Handling Function ofAssociated ObjectAssociated Object


27/28

Asynchronous Request HandlingAsynchronous Request Handling

Process OverviewProcess Overview

Event Handler Returns andControl is Given Back to ActiveScheduler

Active Scheduler Calls EventHandler of Active Object. Event

Handler Cannot be Preempted

Service Completes and ServiceProvider Notifies the Active Schedulerwith Results

Sets the Request Status to Pending

and Starts the Service

Issue Request

Check for Outstanding Requests

Asynchronous ServiceProvider

Active Object

Process Boundary


28/28

ReferencesReferences

Mobile computing : technology, applications,and service creation by Asoke K. Talukder,by Asoke K. Talukder,

Roopa R. YavagalRoopa R. Yavagal

S60 Programming by Paul Coulton and ReubenEdwards

Developing Software for Symbian OS by SteveBabin

The Accredited Symbian Developer Primer byMark Jacobs and Jo Stichbury

symbian application development concepts

Documents