component models - main characteristics ivica crnkovic
TRANSCRIPT
Component Models- main characteristics
Ivica Crnkovic
Outline
• Motivation and goals for using components in Software
• Basic characteristics of component models
• Classification of component models
• Component models examples
21 Apr 2023 2
Challanges of Software Engineering
Page 3, April 21, 2023
• The size & complexity of software increases rapidly
• Single products become part of product families
• Software is upgraded after deployment
• Time-to marked must decrease significntely
• The costs of (software) products must be reduced
Observations on the practice of SE
Page 4, April 21, 2023
• About 80% of software development deals with changing of existing software
• “It is not the strongest of the species that survive, nor the most intelligent, but the ones most responsive to changes”
• Darwin
• We need methods that will– Easy incorporate changes– Adaptations– Be able to fast response to the new requirements
Page 5, April 21, 2023
A possible solution: Component-based Development
• Idea:– Build software systems from pre-existing
components (like building cars from existing components)
– Building components that can be reused in different applications
– Separate development of components from development of systems
Page 6, April 21, 2023
• The software architecture of a program or computing system is the structure or structures of the system, which comprise software components [and connectors], the externally visible properties of those components [and connectors] and the relationships among them.”
Bass L., Clements P., and Kazman R., Software Architecture in Practice,
C1
C4
C2
C5C3
Systems and components – Software Achitectures
21 Apr 2023 7
What is component?• The component case
– Many definitions– Some acknowledge ones:
• software component is a unit of composition with contractually specified interfaces and context dependencies only. A software component can be deployed independently and is subject to composition by third parties.
Szyperski
• A software component is a software element that conforms to a component model and can be independently deployed and composed without modification according to a composition standard
Heineman and Councill
– Intuitive perception may be quite different at different levels (model, implementation, run-time)
Page 8, April 21, 2023
Composition unitA software component is a unit of composition with contractually specified interfaces and explicit context dependencies only. A software component can be deployed independently and is subject to composition by third party. –Clemens Szyperski
How much components fit together?
How much costs the glue code?
ComponentsGlue code
System
Page 9, April 21, 2023
What is a contract?A software component is a unit of composition with contractually specified interfaces and explicit context dependencies only. A software component can be deployed independently and is subject to composition by third party.
• Contract - A specification attached to an interface that mutually binds the clients and providers of the components.– Functional Aspects (API)– Pre- and post-conditions for the operations specified by API.
A component may provide/ implement several interfaces
IBar
IFoo
IFoo2
Page 10, April 21, 2023
What is an explicit context dependency?
A software component is a unit of composition with contractually specified interfaces and explicit context dependencies only. A software component can be deployed independently and is subject to composition by third party.
• Context dependencies - Specification of the deployment environment and run-time environment– Example: Which tools, platforms, resources or other
components are required?
Do existing component models have support for declaring the dependencies?
Is it possible to verify if the environment comply with the context required?
Page 11, April 21, 2023
A software component is a unit of composition with contractually specified
interfaces and explicit context dependencies only. A software component can be deployed independently and is subject to composition by third party.
• Late binding - dependencies are resolved at load or run-time.• Replacing of a component independent of the client (main application) if
the contract is not broken.• Delegation - interaction with a weak coupling (for example no
inheritance).
Which problems can occur in relation to late binding?
How can we guarantee that a replacement of a component will not affect other parts of the system?
What does it mean deployed independently?
Page 13, April 21, 2023
Components and Interfaces - UML definition
Component
Interface
Operation
*
in-interfaces*
*
*
Name
1
1
1 1
1
1
Parameter
1
*
Type
1 *
OutParameterInParameter
InOutParameter
*
out-interfaces
*
Component – a set of interfacesrequired (in-interfaces)provided (out-interfaces)
Interface – set of operationsOperations – input and output parameters of certain type
Page 14, CBSE – graduate
course
Example: Specification of a COM component
interface ISpellCheck : IUnknown{
HRESULT check([in] BSTR *word, [out] bool *correct);};
interface ICustomSpellCheck : IUnknown{
HRESULT add([in] BSTR *word);HRESULT remove([in] BSTR *word);
};
library SpellCheckerLib{
coclass SpellChecker{
[default] interface ISpellCheck; interface ICustomSpellCheck;
};};
Page 15, CBSE – graduate
course
Semantic Specification
• Extension of syntactic specification• A state model is associated with each interface• Operations have pre- and post-conditions
– pre: state * in-parameters -> bool– post: state * state * in-parameters * out-parameters -> bool
• Invariants on an interface’s state model– state -> bool
• Intra-interface conditions for components– state1 * state2 * … -> bool
Page 16, CBSE – graduate
course
Example: UML Component Specification
check(in word : String, out correct : Boolean) : HRESULT
«interface type»ISpellCheck String
1
words
*
add(in word : String) : HRESULTremove(in word : String) : HRESULT
«interface type»ICustomSpellCheck
1
words
*
String
«comp spec»SpellChecker
ISpellCheck
ICustomSpellCheck
Page 17, CBSE – graduate
course
Example: Object Constraint Language (OCL)
context ISpellCheck::check(in word : String, out correct : Boolean) : HRESULTpre:
word <> “”post:
SUCCEEDED(result) implies correct = words->includes(word)
context ICustomSpellCheck::add(in word : String) : HRESULTpre:
word <> “”post:
SUCCEEDED(result) implies words = words@pre->including (word)
context SpellCheckerISpellCheck::words = ICustomSpellCheck::words
Page 18, April 21, 2023
Contractually specified interfaces in a UML metamodel
Interface
Component
*
in-interfaces*
*
out-interfaces
*
State
1 *
Constraint
*
*
* 1
Invariant
1
*
1
*
Operation
*
*
Parameter
1
*
PreCondition
* 1
PostCondition
1 *
1
*
InParameter OutParameter
*
*
*
*
*
*
*
2
Finally- components have attributes
• Extra functional properties– Memory size– Requires CPU– …– Performance
• Response time• Execution time
– Quality attributes• Reliability• Avaliability
21 Apr 2023 19ICAT Sarajevo - 2007-10-29
Components and properties
21 Apr 2023 20
21 Apr 2023 21
Different solutions
• A plethora of CB models (with many different characteristics)
<<component>>
Client
<<component>>
ServerIdenticalItf
C1wcet1f1
A
C2wcet2f2
Inputports
Outputports
AUTOSARBIPCOMDESCCACorba CMEJBFractalKOALAKobrA
MS COMOpenComOSGi PINPECOSROBOCOPRUBUSSaveCCMSOFA 2.0
21 Apr 2023 ICATSarajevo - 2007-10-29 22
Questions– What is common to component models?
– It is possible to identify common principles and common features?
– Is it possible to utilize/instantiate these principles for particular component models in particular domains?
21 Apr 2023 23
Definitions: Software Component – Component Model
Definition: • A Software Component is a software building block that conforms to
a component model. • A Component Model defines standards for
– (i) properties that individual components must satisfy and – (ii) methods, and possibly mechanisms, for composing components.
Classification• (i) Commonalities, (ii) Differences
• Different approaches– Specification of Meta model
– List of characteristics
– Identification of categories and their characteristics
• Component SpecificationC = <{Interfaces}, {Properties}>
• Component Composition:
C = C1 C2
Interaction (Interface composition): I(C) = I(C1) I(C2)
Property composition: Pi(C) = Pi(C1) Pi(C2)• Component Lifecycle
21 Apr 2023 24
21 Apr 2023 25
The Classification Framework - Categories
• Lifecycle. The lifecycle dimension identifies the support provided (explicitly or implicitly) by the component model, in certain points of a lifecycle of components or component-based systems.
• Constructs. The constructs dimension identifies (i) the component interface used for the interaction with other components and external environment, and (ii) the means of component binding and communication.
• Extra-Functional Properties. The extra-functional properties dimension identifies specifications and support that includes the provision of property values and means for their composition.
• Domains. This dimension shows in which application and business domains component models are used.
lifecycle
EFP
Domain A Domain B
The component-based development process
Requirements
Design
Test
Release
Maintenance
Implementation
Integration
Requirements
Design
Test
Release
Maintenance
Implementation
Integration
Requirements
Design
Test
Release
Maintenance
Implementation
Integration
Requirements
Design
Test
Release
Maintenance
Implementation
Integration
Verify
Store
System Development
Component Assessment
Component Development
Select
Find
Requirements
Design
Test
Release
Maintenance
Implementation
Integration
Requirements
Design
Test
Release
Maintenance
Implementation
Integration
Requirements
Design
Test
Release
Maintenance
Implementation
Integration
Requirements
Design
Test
Release
Maintenance
Implementation
Integration
Verify
Store
System Development
Component Assessment
Component Development
Select
Find
Requirements
Design
Test
Release
Maintenance
Implementation
Integration
Requirements
Design
Test
Release
Maintenance
Implementation
Integration
Requirements
Design
Test
Release
Maintenance
Implementation
Integration
Requirements
Design
Test
Release
Maintenance
Implementation
Integration
Requirements
Design
Test
Release
Maintenance
Implementation
Integration
Requirements
Design
Test
Release
Maintenance
Implementation
Integration
Requirements
Design
Test
Release
Maintenance
Implementation
Integration
Requirements
Design
Test
Release
Maintenance
Implementation
Integration
Verify
Store
System Development
Component Assessment
Component Development
Select
Find
The Component lifecycle
Requirements
Design
Test
Release
Maintenance
Implementation
Integration
Requirements
Design
Test
Release
Maintenance
Implementation
Integration
Requirements
Design
Test
Release
Maintenance
Implementation
Integration
Requirements
Design
Test
Release
Maintenance
Implementation
Integration
Verify
Store
System Development
Component Assessment
Component Development
Select
Find
Requirements
Design
Test
Release
Maintenance
Implementation
Integration
Requirements
Design
Test
Release
Maintenance
Implementation
Integration
Requirements
Design
Test
Release
Maintenance
Implementation
Integration
Requirements
Design
Test
Release
Maintenance
Implementation
Integration
Verify
Store
System Development
Component Assessment
Component Development
Select
Find
Requirements
Design
Test
Release
Maintenance
Implementation
Integration
Requirements
Design
Test
Release
Maintenance
Implementation
Integration
Requirements
Design
Test
Release
Maintenance
Implementation
Integration
Requirements
Design
Test
Release
Maintenance
Implementation
Integration
Requirements
Design
Test
Release
Maintenance
Implementation
Integration
Requirements
Design
Test
Release
Maintenance
Implementation
Integration
Requirements
Design
Test
Release
Maintenance
Implementation
Integration
Requirements
Design
Test
Release
Maintenance
Implementation
Integration
Verify
Store
System Development
Component Assessment
Component Development
Select
Find
Component lifecycle
21 Apr 2023 ICAT Sarajevo - 2007-10-29 28
Component lifecyclerequirementsrequirements
modellingmodelling
implementationimplementation
packagingpackaging
deploymentdeployment
ExecutionExecutionSpecification• Interface• Models• Meta data
Specification• Interface• Models• Meta data
Code• Source code• Executable code• Executable models
Code• Source code• Executable code• Executable models
Storage• Repository• Package• Meta data
Storage• Repository• Package• Meta data
InstalledFilesInstalledFiles
ExecutablecodeExecutablecode
Component forms
Constructs – components Interactions
• Specification of– Interface
– Composition (interaction)
21 Apr 2023 30
<<component>>
Client
<<component>>
Client
<<component>>
Server
Double role of Interface
Constructs – Interface Specification
Categories
• Levels– - Syntactic
-Semantic- Behavioral
• Specification language
• Distinquish– Provide
– Require
• Interface type– Operation-based
– Port-based
21 Apr 2023 31
<<component>>
Client
<<component>>
Client
<<component>>
Client
21 Apr 2023 32
Constructs – compositions (I)
<<component>>
Client
Architectural style
(client-server, pipe-filter)
Communication type
(synchronous, asynchronous)
<<component>>
Server
21 Apr 2023 33
Constructs compositions (II)
<<component>>
Client
<<component>>
Server
Exogenous
<<component>>
Client
<<component>>
Server
<<Connector>>In between
<<component>>
Server
Endogenous
C1.x = C2.y
a = C2.yC1.x = a
21 Apr 2023 34
Constructs compositions (III)Composition
Horizontal<<component>>
Client
<<component>>
Server
<<component>>Server
Vertical
<<component>>
Client
<<component>>
Server
Constructs classification
• Interface– operation-based/port-based– provides/requires
– The interface level (syntactic, semantic, behaviour)
– distinctive features
• Connections– Architectural Style– Communication type (synchronous/asynchronous)– Binding type
• Endogenous, Exogenous• Vertical, horisontal
21 Apr 2023 35
21 Apr 2023 36
Extra-Functional Properties
• Management of extra-functional properties– Does a component provide any support for extra-functional
properties?– What are the mechanisms?– Which properties are managed?
• Composition of extra-functional properties– P(C1 o C2) = P(C1) o P(C2)– What kind of composition is supported?– Which properties?
Component Execution Platform
component component
EFP Management EFP Management
Component Execution Platform
EFP Management
component component
Component Execution Platform
component
EFP Management
EFP Management EFP Management
component
Component Execution Platform
component
EFP Management EFP Management
component
EFP Managed systemwideEFP Managed per collaboration
Exogenous EFPmanagement
Endogenous EFPmanagement
A B
C D
Component Execution Platform
component component
EFP Management EFP Management
Component Execution Platform
EFP ManagementEFP Management
component component
Component Execution Platform
component
EFP ManagementEFP Management
EFP ManagementEFP Management EFP ManagementEFP Management
component
Component Execution Platform
component
EFP ManagementEFP Management EFP ManagementEFP Management
component
EFP Managed systemwideEFP Managed per collaboration
Exogenous EFPmanagement
Endogenous EFPmanagement
A B
C D
Management of EFP
EPF – composition types (I)
1. Directly composable properties.
2. Architecture-related properties
3. Derived properties.
4. Usage-depended properties.
5. System environment context properties.
21 Apr 2023 38
EPF – composition types (II)
1. Directly composable properties. A property of an assembly is a function of, and only of, the same property of the components involved.
– P(A) = f(P(C1),…P(Ci),…,P(Cn))
2. Architecture-related properties. A property of an assembly is a function of the same property of the components and of the software architecture.
– P(A) = f(SA, …P(Ci)…), i=1…n
– SA = software architecture
21 Apr 2023 39
EPF – composition types (III)3 Derived properties. A property of an assembly depends on several
different properties of the components. – P(A) = f(SA, …Pi(Cj)…), i=1…m, j=1…n– Pi = component properties– Cj = components
4 Usage-depended properties. A property of an assembly is determined by its usage profile. – P(A,U) = f(SA, …Pi(Cj,U)…), i=1…m, j=1…n – U = Usage profile
5 System environment context properties. A property is determined by other properties and by the state of the system environment.– P(S,U,X) = f(SA, …Pi(Cj,U,X)…), i=1…m, j=1…n – S= system, X = system context
21 Apr 2023 40
21 Apr 2023 41
DomainsApplications and business domain of the Component Models
• General-purpose:– Basic mechanisms for the production and the composition of
components – Provide no guidance, nor support for any specific architecture.
• Specialised:– Specific application domains
(i.e. consumer electronics, automotive, …)
• Generative:– Instantiation of particular component models– Provide common principles and some common parts of technologies
(for example modelling)– Other parts are specific (for example different implementations)
21 Apr 2023 42
21 Apr 2023 43
Illustration of the Classification Framework use
• Survey of 20 component models
• Selection of documentation for each component model– Satisfies criteria– Disponibility the definition (Interfaces, composition)
– Some points in the table have been subject our interpretation.
21 Apr 2023 44
Chosen component models
• AUTOSAR
• BIP
• COMDES
• Common Component Architecture (CCA)
• CompoNETS
• CORBA Component Model (CCM)
• The Entreprise JavaBeans (EJB
• Fractal
• The K-Component Model
• KobrA
• Koala
• PIN
• Microsoft Component Object Model (COM)
• OpenCOM • The Open Services Gateway
Initiative (OSGi) • Palladio• Pin • Robocop • Rubus • SaveCCM
21 Apr 2023 45
Lifecycle table Component
ModelsModelling Implementation Packaging Deployment
AUTOSAR N/A C Non-formal specification of container At compilation
BIPA 3-layered representation: behavior, interaction,
and priorityBIP Language N/A At compilation
BlueArX N/A C N/A At compilation
CCM N/A Language independentDeployment Unit archive
(JARs, DLLs)At run-time
COMDES II ADL-like language C N/A At compilation
CompoNETS Behavour modeling (Petri Nets) Language independentDeployment Unit archive
(JARs, DLLs)At run-time
EJB N/A Java EJB-Jar files At run-time
FractalADL-like language
(Fractal ADL, Fractal IDL), Annotations (Fractlet)
Java (in Julia, Aokell)C/C++ (in Think)
.Net lang. (in FracNet)File system based repository At run-time
KOALA ADL-like languages (IDL,CDL and DDL) C File system based repository At compilation
KobrA UML Profile Language independent N/A N/A
IEC 61131Function Block Diagram (FBD)
Ladder Diagram (LD)Sequential Function Chart (SFC)
Structured Text (ST)Instruction List (IL)
N/A At compilation
IEC 61499 Function Block Diagram (FBD) Language independent N/A At compilation
JavaBeans N/A Java Jar packages At compilation
MS COM N/A OO languages DLLAt compilation and at run-
timeOpenCOM N/A OO languages DLL At run-time
OSGi N/A Java Jar-files (bundles)At run-time and at
compilationPalladio UML profile Java N/A At run-timePECOS ADL-like language (CoCo) C++ and Java Jar packages or DLL At compilation
Pin ADL-like language (CCL) C DLL At compilationProCom ADL-like language, timed automata C File system based repository At compilation
ROBOCOP ADL-like language, resource management model C and C++ Structures in zip filesAt compilation and at run-
timeRUBUS Rubus Design Language C File system based repository At compilation
SaveCCM ADL-like (SaveComp), timed automata C File system based repository At compilationSOFA 2.0 Meta-model based specification language Java Repository At run-time
21 Apr 2023 46
Lifecycle table Component
ModelsModelling Implementation Packaging Deployment
AUTOSAR N/A CN/A
At compilation
BIP
A 3-layered representation:
behavior, interaction and priority
Source code, implementation in
BIP languageN/A
At compilation
CCM
Abstract model:OMG-IDL,
Programming model: CIDL
Language independent.
Deployment Unit archive
(JARs, DLLs)At run-time
Fractal
ADL-like language (Fractal ADL, Fractal
IDL), Annotations (Fractlet)
Julia, Aokell(Java)Think(C/C++)FracNet(.Net)
File system based repository
At run-time
KOALAADL-like languages
(IDL,CDL and DDL)C
File system based repository
At compilation
EJB N/A Java binary code EJB-Jar files At run-time
21 Apr 2023 47
Constructs table - Interface
ComponentModels
Interface type
Distinction of
Provides / Requires
Distinctive featuresInterface Language
Interface Levels
(Syntactic,Semantic,
Behaviour)
AUTOSAROperation-
basedPort-based
Yes AUTOSAR Interface* C header files Syntactic
BIP Port-based No Complete interfaces,Incomplete interfaces
BIP LanguageSyntacticSemanticBehaviour
BlueArX Port-based Yes N/A C Syntactic
CCMOperation-
basedPort-based
YesFacets and receptaclesEvent sinks and event
sources
CORBA IDL, CIDL Syntactic
COMDES II Port-based Yes N/AC header filesState charts diagrams
SyntacticBehaviour
CompoNETS
Operation-based
Port-basedYes
Facets and receptaclesEvent sinks and event
sources
CORBA IDL, CIDL,
Petri netsSyntacticBehaviour
EJB Operation-based No N/A
Java Programming Language + Annotations
Syntactic
Fractal Operation-based Yes Component Interface,
Control Interface
IDL, Fractal ADL, or Java or
C, Behavioural
Protocol
SyntacticBehaviour
KOALA Operation-based Yes Diversity Interface,
Optional InterfaceIDL, CDL Syntactic
21 Apr 2023 48
Constructs table - interactionCOMPONENT
MODELSINTERACTION
STYLESCOMMUNICATION
TYPE
BINDING TYPE
EXOGENOUS HIERARCHICAL
AUTOSAR Request response, Messages passing
Synchronous, Asynchronous No Delegation
BIPTriggering
Rendez-vous, Broadcast
Synchronous, Asynchronous No Delegation
BlueArX Pipe&filter Synchronous No Delegation
CCM Request response, Triggering
Synchronous, Asynchronous No No
COMDES II Pipe&filter Synchronous No No
CompoNETS Request response Synchronous, Asynchronous No No
EJB Request response Synchronous, Asynchronous No No
Fractal Multiple interaction styles
Synchronous, Asynchronous Yes Delegation,
Aggregation
KOALA Request response Synchronous No Delegation, Aggregation
21 Apr 2023 49
EFPComponent
ModelsManagement of EFP Properties specification
Composition and analysis support
BlueArX Endogenous per collaboration (A) Resource usage, Timing properties N/A
EJB 3.0 Exogenous system wide (D) N/A N/A
Fractal Exogenous per collaboration (C)Ability to add properties (by adding
“property” controllers)N/A
KOALA Endogenous system wide (B) Resource usage Compile time checks of resources
KobrA Endogenous per collaboration (A) N/A N/A
Palladio Endogenous system wide (B) Performance properties specification Performance properties
PECOS Endogenous system wide (B)Timing properties, generic
specification of other propertiesN/A
Pin Exogenous system wide (D) Analytic interface, timing propertiesDifferent EFP composition theories, example latency
ProCom Endogenous system wide (B) Timing and resources Timing and resources at design
and compile time
Robocop Endogenous system wide (B)Memory consumption, Timing
properties, reliability, ability to add other properties
Memory consumption and timing properties at deployment
Rubus Endogenous system wide (B) Timing Timing properties at design time
SaveCCM Endogenous system wide (B)Timing properties, generic
specification of other propertiesTiming properties at design time
SOFA 2.0 Endogenous system wide (B) Behavioural (protocols) Composition at design
21 Apr 2023 50
Domains
21 Apr 2023 51
Conclusion• From the results we can recognize some recurrent patterns such as
– general-purpose component models utilize client-server style
– Specialized domains (mostly embedded systems) pipe & filter is the predominate style.
– Composition of extra-functional properties is rather scarce.
– Behaviour & Semantic rarely supported
– Almost never repository