Java in the Box: Java in the Box: Implementing the BoxScript Implementing the BoxScript

Component LanguageComponent Language

Yi LiuYi LiuElectrical Engineering and Computer Science Electrical Engineering and Computer Science

South Dakota State UniversitySouth Dakota State University

H. Conrad CunninghamH. Conrad CunninghamComputer and Information ScienceComputer and Information Science

University of MississippiUniversity of Mississippi

22

Software Components Software Components

33

Components – A Closer LookComponents – A Closer Look

Component1

provided required

interface

inner component Component2

required provided

44

A Simple ExampleA Simple Example

Discounting

CalPrice

Discounting2

CompositionalityFlexibility

Storage Pricing

Pricing

Discounting

Storage Discounting2

55

Key Concepts Key Concepts InterfaceInterface

Interface (type)Interface (type)– Java interface gives operation signaturesJava interface gives operation signatures

Provided interfaceProvided interface– describes operations the component implements that describes operations the component implements that

other components may use other components may use Required interfaceRequired interface

– describes operations the component uses that must be describes operations the component uses that must be implemented by another componentimplemented by another component

Price.java public interface Price{ double getPrice(int client, int item, int quantity); }

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Key Concepts Key Concepts BoxBox

A box is a component A box is a component – whose description includes provided and required whose description includes provided and required

interfaces interfaces

– has 1..n provided interfaceshas 1..n provided interfaces

– has 0..m required interfaceshas 0..m required interfaces Boxes may beBoxes may be

– abstractabstract

– concreteconcrete atomicatomic compoundcompound

Box

… P1 Pn

…

R1 Rn

1…n

0…m

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Key Concepts Key Concepts Abstract BoxAbstract Box

Abstract boxAbstract box– does not implement provided interfaces does not implement provided interfaces – implemented by concrete boxes implemented by concrete boxes

PricingAbs.boxPricingAbs.boxabstract box PricingAbsabstract box PricingAbs{ provided interface Price Pr; { provided interface Price Pr; required interface Discount Dc,required interface Discount Dc,

PriceRetrieve PrRt;PriceRetrieve PrRt;}}

Interface typeInterface Handle

PricePr

PricingAbs

Discount

DcPriceRetrie

ve

PrRt

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Key Concepts Key Concepts Concrete BoxConcrete Box

Atomic boxAtomic box– does not contain any other boxesdoes not contain any other boxes– implements the provided interfacesimplements the provided interfaces

Pricing.boxPricing.boxbox Pricing implements PricingAbsbox Pricing implements PricingAbs{ provided interface Price Pr; { provided interface Price Pr; required interface Discount Dc; required interface Discount Dc; }}

Interface handle

Interface type

PricePr

Pricing

Discount

DcPriceRetrie

ve

PrRt

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Key Concepts Key Concepts Interface Implementation for Atomic BoxInterface Implementation for Atomic Box

PrImp.java PrImp.java public class PrImp implements Pricepublic class PrImp implements Price{ private BoxTop _box; { private BoxTop _box; Discount dc; // required interfaceDiscount dc; // required interface PriceRetrieve prRt; //required interfacePriceRetrieve prRt; //required interface public PrImp(BoxTop myBox)public PrImp(BoxTop myBox) { { __box = myBox;box = myBox; InterfaceName name = new InterfaceName("Dc");InterfaceName name = new InterfaceName("Dc"); dc = (Discount)_box.getRequiredItf(name);dc = (Discount)_box.getRequiredItf(name); name = new InterfaceName(“PrRt");name = new InterfaceName(“PrRt"); prRt = (PriceRetrieve)_box.getRequiredItf(name);prRt = (PriceRetrieve)_box.getRequiredItf(name); }} public double getPrice(int client,int item,int quantity)public double getPrice(int client,int item,int quantity) { double price = prRt.itemPrice(item);{ double price = prRt.itemPrice(item); double disc = dc.getDiscount(client, item, quantity);double disc = dc.getDiscount(client, item, quantity); return price * (1 – disc * 0.01) * quantity;return price * (1 – disc * 0.01) * quantity; }}}}

PricePr

Pricing

Discount

DcPriceRetrie

ve

PrRt

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Key Concepts Key Concepts Compound BoxCompound Box

Compound boxCompound box– Composed from atomic boxes or other Composed from atomic boxes or other

compound boxescompound boxes– Follows composition rulesFollows composition rules

hide provided interfaces unless explicitly exposed hide provided interfaces unless explicitly exposed must expose required interface of constituent must expose required interface of constituent

unless connected to provided interface of another unless connected to provided interface of another constituentconstituent

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Key ConceptsKey Concepts Compound Box ExampleCompound Box Example

box box CalPriceCalPrice implements CalPriceAbs implements CalPriceAbs{ { composed fromcomposed from PricingAbs PricingAbs boxPboxP, DiscountingAbs , DiscountingAbs boxD, boxD, StorageAbsStorageAbs boxSboxS ; ; provided interface Price provided interface Price tPricetPrice fromfrom boxP.PrboxP.Pr; ; connectconnect boxP.DcboxP.Dc toto boxD.Dis, boxP.PrRt boxD.Dis, boxP.PrRt toto boxS.PrRt; boxS.PrRt; }} tPric

ePrice

CalPriceCalPrice

Discount Dis

DiscountingAbs boxD

box handle

PriceRetrieve PrRt

StorageAbs boxS

Pr

PricingAbs boxP

DiscountDc

Price

PriceRetrievePrRt

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Key ConceptsKey Concepts Box VariantBox Variant

Box variantsBox variants– Enable flexibility Enable flexibility – Implement same (parent) abstract boxImplement same (parent) abstract box– Can be substituted for each otherCan be substituted for each other– Conform to their (parent) abstract boxConform to their (parent) abstract box

provide at least the provided interfaces of parentprovide at least the provided interfaces of parent require at most the required interfaces of parentrequire at most the required interfaces of parent

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Key ConceptsKey Concepts Box ConformityBox Conformity

B BAbs

P1 P2 P3

IP1 IP2’ IP3

R1 R2 IR1 IR2

P1 P2

IP1 IP2

R1 R2 IR1’ IR2 IR3

R3

SupposeSuppose IP2’ extends IP2IP2’ extends IP2 IR1’ extends IR1IR1’ extends IR1

B conforms to BAbs

Provided interfaces

Required interfaces

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BoxScript ImplementationBoxScript ImplementationBox Source Code and CompilationBox Source Code and Compilation

For all boxesFor all boxes– interfaces (.java) interfaces (.java) by user by user – box description (.box) box description (.box) by user by user

For atomic boxes onlyFor atomic boxes only– interface implementation (.java) interface implementation (.java) by user by user

For concrete boxes only For concrete boxes only – configuration information (.conf) configuration information (.conf) by user by user – box manager code (.java) box manager code (.java) by compiler by compiler

Box code BoxCompiler Java code Java Compiler

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BoxScript Implementation BoxScript Implementation Box Manager ImplementationBox Manager Implementation

packagepackage declaration declaration– define filesystem usagedefine filesystem usage

importimport– interfaceinterface declarationsdeclarations

– data type declarationsdata type declarations variable declarationsvariable declarations

– instance variables for classinstance variables for class classclass definition definition

Concrete Box B

B.java

Box manager

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BoxScript ImplementationBoxScript Implementation Box Runtime StructureBox Runtime Structure

<<Java class >> Pricing

<<Java class >> Discounting

<<Java class >> PrImp

<<interface >> Price

<<Java class >> DisImp

<<interface >> Discount

implements

implements

instantiates

instantiates

constructor Pricing

constructor Discounting

<<Java class >> CalPrice

constructor CalPrice

instantiates Pricing

instantiates Discounting

references

references

Lazy instantiation

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BoxScript ImplementationBoxScript Implementation Box Manager CodeBox Manager Code

Generated by compilerGenerated by compiler– to instantiate box instancesto instantiate box instances

– to assign references to interface handlesto assign references to interface handles

1818

BoxScript Implementation BoxScript Implementation Box Manager ImplementationBox Manager Implementation

Supports lazy instantiation Supports lazy instantiation – BoxTopBoxTop

BoxTop

BoxTop()void setProvInterfacceDsc(InterfaceDsc pItfDsc)void setRequInterfaceDsc(InterfaceDsc rItfDsc)Object getProvidedItf(InterfaceName name)Object getRequiredItf(InterfaceName name)void setRequiredItf(InterfaceName iname, Object objRef)

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BoxScript Implementation BoxScript Implementation Box Manager ImplementationBox Manager Implementation

Code generation Code generation

generateCode (B’dscFile, mngFile) //mngFile : filename for box manager generateCode (B’dscFile, mngFile) //mngFile : filename for box manager

read in dscFile read in dscFile

genPackage();genPackage();

genImports();genImports();

genVars();genVars();

genConstructor();genConstructor();

genGetProvidedItf(); genGetProvidedItf(); // generate overriding method getProvidedItf// generate overriding method getProvidedItf

if B is compoundif B is compound genSetRequiredItf(); genSetRequiredItf(); // generate overriding method// generate overriding method setRequiredItfsetRequiredItf

writeIntoFile(mngFile);writeIntoFile(mngFile);

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ConclusionConclusion

Component-oriented programming Component-oriented programming language BoxScriptlanguage BoxScript– Builds upon JavaBuilds upon Java– Provides novel concepts of Provides novel concepts of

box type structure box type structure box variantsbox variants box conformitybox conformity interface satisfaction interface satisfaction

to support to support compositioncomposition and and flexibilityflexibility

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QuestionsQuestions