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Chi-I Hung

Introduction of SDLIntroduction of SDL

Chi-I HungCCL/ITRI

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Collected by the United States Department of Defence

from nine large software projects

Software Projects StatisticsSoftware Projects Statistics

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Software CostsSoftware Costs

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Specification and Description LanguageSpecification and Description Language

SpecificationSpecification----A specification of a system is the description

of its required behaviour

DescriptionDescription----A description of a system is the description

of its actual behaviour

The Purpose of SDLThe Purpose of SDLProvide a language for unambiguous specificationProvide a language for unambiguous specification

and description of the behaviour ofand description of the behaviour of

telecommunications systems.telecommunications systems.

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Objective of SDLObjective of SDL

Formal description technique Easy to understand both for creators

(direct users) and viewers (non constructors

of specifications)

(graphical representation)

Object oriented language Independent of design paradigm

(e.g. function or object oriented)

Independent of implementation(language, operating system, and hardware)

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Usage of SDLUsage of SDL

a) facility requirements;

b) system specifications;

c) ITU-T Recommendations, or other similar Standards

(international, regional or national);

d) system design specifications;

e) detailed specifications;f) system design descriptions

(both high level and detailed enough to

directly produce implementations);g) system testing descriptions

(in particular in combination with MSC and TTCN).

(From ITU-T Z.100)

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Improvement of Error RateImprovement of Error Rate

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Process Dimension - CMMIProcess Dimension - CMMI

Process Management Organizational Process Focus Organizational Process Definition

Organizational Training Organizational Process Performance Organizational Innovation and Deployment

Support Configuration Management Process and Product Quality Assurance

Measurement and Analysis Decision Analysis and Resolution Causal Analysis and Resolution Organizational Environment for Integration

Project Management

Project Planning Project Monitoring and Control Supplier Agreement Management Integrated Project Management Integrated Teaming

Risk Management Quantitative Project Management

EngineeringEngineering Requirements ManagementRequirements Management

Requirements DevelopmentRequirements Development Technical SolutionTechnical Solution

Product IntegrationProduct Integration

VerificationVerification ValidationValidation

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SDL-76 First version. Only recommendations on how to

draw process graph symbols (Behavior).

SDL-80 Blocks are introduced (Architecture), PR-form

(textual Phrase Representation) becomes a

part of the language.

SDL-84 The abstract data type concept is introduced(Data). Additional concepts are introduced.

SDL-88 Only minor changes

SDL-92 Object-oriented extensions to SDLSDL-96 Minor changes (e.g. external procedures)

SDL-2000 Changes regarding architecture and data model.

SDL HistorySDL History

International Standard (ITU-T, Z.100)International Standard (ITU-T, Z.100)

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Application of SDLApplication of SDL

call and connection processing

(for example, call handling, telephony signalling, metering)

in switching systems

maintenance and fault treatment

(for example alarms, automatic fault clearance, routine tests)

in general telecommunications systems

system control

(for example, overload control, modification

and extension procedures) operation and maintenance functions, network management

data communication protocols

telecommunications services

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SDL Design MethodologySDL Design Methodology

Flow of Software Development

Basic Concept of SDL Design Flow

Basic Component of SDL

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Flow of Software DevelopmentFlow of Software Development

SoftwareRequirement

Analysis

Design

Testing

CodingSDL EditorMSC Editor

SDL CodeGenerator

SDL Simulator

TTCN Simulator

UML

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Protocol Development ProcessProtocol Development Process

ProtocolSpecification

SoftwareRequirement

Formal DescriptionFormal DescriptionLanguageLanguage- SDL- SDL- UML-2- UML-2

Test Suite-- TTCN-2

-- TTCN-3

Host Conformance Test

ExecutionTest Suite

Code-Generation

ImplementationUnder Test

(IUT)

Code-Generation

Conformance Test

ProductProduct

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Basic Concept of SDL Design FlowBasic Concept of SDL Design Flow

SystemArchitecture--SDL Editor

Use Cases

--MSC Editor

SDL Coding

Code Analyze

Code Gen

Simulation

OKNo

SDL Code-Gen

Yes

C/C++Source Code

Other

Source Code

or Object Code

Compile &

Link

Execution

File

OS Lib.

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Basic Component of SDLBasic Component of SDL

Architecture

- system, block

Behavior- processes

Communication

- signals and channelsData

- abstract data types

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SDL Architecture -- SystemSDL Architecture -- System

SDL SystemSDL System A SDL-system is the outermost agent that communicates

with the environment.

EnvironmentEnvironment : The environment of the system is everything in the

surroundings that communicates with the system in

an SDL-like way.

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A SDL System must define the interfaces to communicate

with other components

SDL-System Structural Concepts (1)SDL-System Structural Concepts (1)

A complete SDL system must contain at least one block A block must contain at least one process or block,

blocks and processes must not be mixed in one block.

A process must contain an finite state machine

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SDL S t St t l C t (2)

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Hierarchical StructureHierarchical Structure

SDL-System Structural Concepts (2)SDL-System Structural Concepts (2)

Block Game

SYSTEM DemonGame 1(1)

Demon(1,1) Monitor(1,1)

BLOCK Game 1(1) PROCESS Monitor(1,1) 1(1)

ReadyWaitIDLE

MAC_Est_Req/MAC_Est_Cnf

MAC_Release_Req

MAC_Con_Req/MAC_Con_Cnf

MAC_Release_Req

Finite State Machine

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SDL S S l C (3)

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SDL-System Structural Concepts(3)SDL-System Structural Concepts(3)

A SDL System can contains :

System Name

SDL Blocks

Channels: The relation between the system and the

outside world.

Signal Definition

Data Type Definition

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SDL Bl kSDL Bl k

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SDL-BlockSDL-Block

A block can be refined either by a set ofprocessesprocesses

or by a set ofblock substructures.

Blocks are static entities in SDL.

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SDL S t E l (1)SDL S t E l (1)

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SDL-System Example (1)SDL-System Example (1)

NASNASUMTS-UEUMTS-UE

L1L1

APAPSDL-System

EnvironmentSDL-Block

L3L3

L2L2

ASAS

RLC

RLCRLC

MACMACMAC SDL-Process

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SDL S t E l (4)SDL System Example (4)

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process RLC

State_0

State_0

Input_Signal

RLC_Data_Req

State_1

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SDL PSDL Process

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SDL ProcessSDL Process

Processes are the actors of SDL systems.

An SDL process is the active unit of an SDL system.

An SDL process represents an extended finite statemachine.

Processes may be defined with an initial and a maximum

number of instances

SDL processes can communicate by means of

asynchronous message passing with other processes.

(init,max)

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El t f SDL PEl t f SDL P

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Elements of SDL ProcessElements of SDL Process

The SDL Process may contain:The SDL Process may contain:

Process nameProcess name

Formal ParametersFormal Parameters

Local VariablesLocal Variables

Time and timersTime and timers

The graphical representation of a FSMThe graphical representation of a FSM

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Behavior of SDLBehavior of SDL

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Behavior of SDLBehavior of SDL

SDL Process as Finite State MachineSDL Process as Finite State Machine

In SDL ,the FSM is extended with data processing (EFSM)

Send no wait, asynchronous signalling

Process instances can be created and terminateddynamically

A process is activated by means of an arriving signal. Atthe end of a transition the next state is entered.

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Process SymbolsProcess Symbols

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Process SymbolsProcess Symbols

process reference

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Input / Output SymbolInput / Output Symbol

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Input / Output SymbolInput / Output Symbol

process MAC

State_0

State_0

RLC_Data_Req

Out_Sig

State_1

process RLC

State_0

State_0

Input_Signal

RLC_Data_Req

State_1

block L2

RLC

MAC

RLC_MAC_Queue

RLC_Data_Req

The RLCRLC will send RLC_Data_RLC_Data_ReqReq to MACMAC viaRLC_MAC_QueueRLC_MAC_Queue

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Input PortInput Port

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Input PortInput Port

Each process instance has a FIFO queue of its own

The port allows received signals (and timeouts)to be

queued until they are consumed (or discarded) by the

owning process instance.

The queues have an infinite capacity.

The FIFO order in processing the queue

is NOTNOT always preserved(because of priority/save ).

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SDL Process IDSDL Process ID

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SDL Process IDSDL Process ID

Each SDL process maintains a set of intrinsic variables whichare of the predefined data type PIdPId (Process Identity)

self :self : Denotes the PId of the process instance itself

sender:sender: Denotes the PId of the process instance from which

the most recent signal has been consumed parent:parent: Denotes the PId of the process instance that

has created the instance

offspring:offspring: Denotes the PId of the most recent process instance

created by this process instance.

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Dynamic Process CreationDynamic Process Creation

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block L2

RLC

MAC(0,5)

RLC_MAC_Queue

Dynamic Process CreationDynamic Process Creation

process RLC

State_0

State_0

Input_Signal

Output_Signal

State_1

MAC

Created processes must lie in the same block.

Termination of a process can only be made by itself.

process MAC

S0

S0

Stop_Req

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SDL ProcedureSDL Procedure

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SDL ProcedureS ocedu e

Procedures can have IN or IN/OUT parameters.Procedures can have IN or IN/OUT parameters.

Procedures can return a value.Procedures can return a value.

SDL procedures can contain states and variableSDL procedures can contain states and variable

declarations.declarations.

Procedure states are disjoint from process stateProcedure states are disjoint from process state

space.space. Procedures can see the variables of the owningProcedures can see the variables of the owning

process.process.

Procedures can only use timers declared in theProcedures can only use timers declared in the

owning process.owning process.

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SDL ProcedureSDL Procedure

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S ocedu e

MyProcedure

;FPARIN arg1 integer,IN/OUT arg2 integer;RETURNS ret_val integer;

procedure MyProcedure

DCL Total Integer;

Total:=arg1+arg2;

Total

Ret_val:=call MyProcedure(1,my_arg)

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SDL ChannelSDL Channel

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Communication path between blocks itself and betweenCommunication path between blocks itself and between

blocks and the environmentblocks and the environment

Channels can be unidirectional orChannels can be unidirectional or bidirectionalbidirectional communicationcommunication

devices.devices.

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SDL RouteSDL Route

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A signal route defines a communication path between aA signal route defines a communication path between aprocess and its environment or another process.process and its environment or another process.

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SignalsSignals

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gg

Signals are the primary communication mechanism in SDLSignals are the primary communication mechanism in SDL

Signals may carry data by means of parameters.Signals may carry data by means of parameters.

All signals to and from the environment are declaredAll signals to and from the environment are declared

at system level.at system level.

Signals can be defined inside a block (thus onlySignals can be defined inside a block (thus only

visible in the block)visible in the block)

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Signal Addressing & RoutingSignal Addressing & Routing

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g g gg g g

If there are several possible receivers of a signal,If there are several possible receivers of a signal,the signal will be delivered to an arbitrary receiver.the signal will be delivered to an arbitrary receiver.

A

B(1,1)

C(1,1)

D(1,1)

Sig1

Sig1

C1

C2

Example:

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Signal Addressing & RoutingSignal Addressing & Routing

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g g gg g g

SDL provide two way for addressing:SDL provide two way for addressing:

VIAVIA : Specifies a signal path

TOTO : Specifies a receiving process

Example 1: A SendSig1Sig1 to B

Sig1 VIAVIA C1

Example 2: A SendSig1Sig1 to C

Sig1 ToTo C

Sig1 ToTo BOR

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SDL DataSDL Data

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Based on abstract data typesBased on abstract data types

- An abstract data type defines a type of data object by its

functional properties,i.e.by a set of operations applied to it.

In SDL,data types are calledIn SDL,data types are called sortssorts

Variables can only be declared in processesVariables can only be declared in processes

- No global variables.- No global variables.

In SDL inheritance and generics are supportedIn SDL inheritance and generics are supported

A new data type is defined by:A new data type is defined by:

- constants and a set of values- operators

- axioms

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SDL Predefined Data SortsSDL Predefined Data Sorts

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IntegerInteger

NaturalNatural

RealReal BooleanBoolean

CharacterCharacter

CharstringCharstring PIdPId

DurationDuration

TimeTime

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BooleanBoolean

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Boolean is a typical example of a data type in SDLBoolean is a typical example of a data type in SDL

NEWTYPENEWTYPEBoolean

LITERALSTrue, False;

OPERATORSNOT:Boolean ->Boolean;

= :Boolean, Boolean ->Boolean;

/=:Boolean, Boolean ->Boolean;

AND:Boolean, Boolean ->Boolean;OR:Boolean, Boolean ->Boolean;

XOR:Boolean, Boolean ->Boolean;

=>:Boolean, Boolean ->Boolean;

AXIOMSNOT(True)== False;

NOT(False)== True;

...

ENDNEWTYPEENDNEWTYPEBoolean;

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Variable Declaration and UseVariable Declaration and Use

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process RLC 1(1)DCL Count Integer;

State_0

State_0

Input_Signal

Count:=1

Output_Signal

State_1

State_1

Input_Signal

Count

Out_Signal

20

30

40

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Task and DecisionTask and Decision

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TheThe TaskTask symbol is used for assignmentssymbol is used for assignments A decision is much like anA decision is much like an ififoror casecasestatement.statement.

i:=i+1;

k:= i mod 7;

Number

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With Synonym, constants are declared in SDLWith Synonym, constants are declared in SDL

- Can be used in SDL-System or Blocks- Can be used in SDL-System or Blocks

- If a constant is declared as EXTERNAL it means that the constant- If a constant is declared as EXTERNAL it means that the constant

will be assigned first at system start-up time (i.e. it can be assignedwill be assigned first at system start-up time (i.e. it can be assigned

different values each time).different values each time).

SYNONYM Zero Integer = 0;SYNONYM One Integer = 1;SYNONYM NrOfDoors Natural = EXTERNAL;

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NewtypeNewtype

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NewtypeNewtype creates a new data typecreates a new data type

Newtype SeqNum

literals zero, one;operatorssucc :

SeqNum -> SeqNum;axioms

succ( zero) == one;succ( one) == zero;

Endnewtype SeqNum;

Newtype EyeColorType

LITERALS Blue, BrownDEFAULTBlueEndnewtype EyeColorType;

DCL MySeqNum SeqNum;

DCL MyEye EyeColorType;

SeqNum := zero;

SeqNum := succ(SeqNum );

MyEye := Brown;

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Restrict the set of values of a ground typeRestrict the set of values of a ground type--NOTE! The syntype will not be a new type but a subtype,

and can thus be assigned values of the ground type.

SYNTYPE Age = Natural

CONSTANTS 0:100

ENDSYNTYPE Age;

DCL

MyAge, YourAge Age;

MyAge:=1,YourAge:=100

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StructStruct

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StructStruct is a data type where the data structure is explicitly statedis a data type where the data structure is explicitly stated

- StructStruct in SDL is similar to struct in C-Language

typedef enum{type_802_11_a,type_802_11_b,type_802_11_g,

} Connect_Type;

typedef struct{

Connect_Type con_type;

char id;int timing ;

} Con_Req_Arg;

newtype Connect_Typeliterals type_802_11_a,

type_802_11_b,

type_802_11_g;

endnewtype Connect_Type;

newtype Con_Req_Arg struct

con_type Connect_Type;

id Character;

timing Integer;endnewtype Con_Req_Arg;

structstructin Cin C structstructin SDLin SDL

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TimerTimer

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On timeout, a signal is sent to the process instanceOn timeout, a signal is sent to the process instance

that set the timer.that set the timer.

TIMER T;SYNONYM p Duration = 5;

disconnected

ICONreq

SET(now + p, T)

Wait

T

disconnected

RESET(T)

SET:- Start a timer with time value

RESET:- The associated time value is lost- Corresponding signal in the inputport is removed

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GeneratorGenerator

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The Generator is like theThe Generator is like the templatetemplate in C++in C++

NEWTYPE intint_set_setLITERALS empty_int_set;

OPERATORS

add: int_set, Integer -> int_set;

is_in: int_set, Integer -> Boolean;AXIOMS

FOR ALL m, n IN Integer, s IN int_set

...

ENDNEWTYPE:

NEWTYPE real_setreal_setLITERALS empty_real_set;

OPERATORS

add: real_set, Integer -> real_set;

is_in: real_set, Integer -> Boolean;AXIOMS

FOR ALL m, n IN Integer, s IN real_set

...

ENDNEWTYPE;

GENERATORsetset(TYPE element, LITERALS empty_set)

LITERALS empty_set;

OPERATORS

add: set, element -> set;is_in: set, element -> Boolean;

AXIOMS

FOR ALL m, n IN element, s IN set

.

ENDGENERATOR;

NEWTYPE intint_set_set set (Integer, empty_int_set)

ENDNEWTYPE;

NEWTYPE real_setreal_set set (real, empty_real_set)

ENDNEWTYPE;

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ArrayArray

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Array is the predefined generator.Array is the predefined generator. --GENERATOR Array(TYPE Index, TYPE Itemsort);

SYNTYPE IndexType = Natural

CONSTANTS 1:100

ENDSYNTYPE;

NEWTYPE Person STRUCT

theName Charstring;

theAge Age;

theEyeColor EyeColorType;

ENDNEWTYPE Person;

NEWTYPE PArrayType

Array (IndexType, Person)

ENDNEWTYPE PArrayType;

DCL PersonArray PArrayType;

PersonArray(2):= (. John, 26, Blue .)

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System Integration (i)System Integration (i)

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SDL system (process) Light IntegrationLight Integration

Process

Instance

CommunicationAdaptor

operating system

-- I/O ,Timer ,Process Management ,IPC ...

Non-SDL Process

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System Integration (ii)System Integration (ii)

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SDL process 1

Tight IntegrationTight Integration

Process

Instance


operating system

-- I/O ,Timer ,Process Management ,IPC ...

Non-SDL Process

SDL process 2

Process

Instance


SDL process 3

Process

Instance


sdl_net2

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