Object-oriented. Service Innovation

Transcription

1 Object-oriented Service Innovation

2 Overall Concepts Real World OO World Collaboration Delegation using services at SAP (service access point) 사과 3 개 Abstract Interacting, Collaborating Objects by Delegating Tasks via API (application program interface) Anthropomorphize 2

3 Service Collaboration by layering??? A Cart in a real world 필요한장좀봐올래? 구매목록 Public methods (APIs) additem( 상품 ) removeitem( 상품명 ) emptycart() gettotalamount() gettotalquantity() getitem( 상품명 ) listlitems() Personified shopping cart 3

4 Layered Architecture in a real-world Layering One of the most common techniques to provide services to others, not only in IT, but also in real world. Basic mechanism to break apart or hide complicated something. The way we collaborate. Presentation Logic Clients User oriented language Business / Domain Logic 매출관리 판매관리 송장관리 Business oriented language Everybody has to know everything. Data Source Logic 문서창고 문서관리 Physical Languages Data oriented language 4

5 View on Service and API Service The word service ordinarily refers to one person performing some work or task for somebody else. A slightly more general definition of service is a person or an organization performing some work for another person or organization. An Application Programming Interface (API) is a specification intended to be used as an interface by software components to communicate with each other. Interacting objects 5

6 Encapsulation: Information Hiding ( 情報隱匿 ) Encapsulation Information Hiding Is the natural characteristic of the Service. 서비스요청자는기대하는서비스결과만을요구하며서비스제공자가서비스를제공하는구체적인방법은상관하지도않을뿐만아니라, 할필요도없다. Is the result/act of hiding the implementation details of an object from its user. Object 외부로노출된서비스 (public methods) 내부에내재된서비스 (private methods) 내부데이터의보호 - 입력 (setter methods) - 출력 (getter methods) Responsibility-driven design (RDD, 책임관점설계 ) 협업의기본 goes beyond information hiding, means that the responsibility of service is belong to a service provider, not to a service requester. 정보은닉 (information hiding) 개념을뛰어넘어모든서비스의책임은의뢰자가아닌수신자 ( 서비스제공자 ) 의책임이라는개념임. 6

7 Restrictions of encapsulation Requests are only way to get an object to execute an operation. Object s internal data can not be accessed directly (private/protected), and its representation is invisible from outside the object. Operations (getter methods) are the only way to get an object s internal data. Operations (setter methods) are the only way to change an object s internal data. Object Benefits When there is information hiding, there cannot be regression faults. The resulting information system consists of essentially independent classes that communicate by sending messages to their own operations and the operations of other classes. 모든내부 data 는 private 으로선언 7

8 Views on the Problem Domain We model the system a number of objects that interact / collaborate. Object orientation is ideally suited to creating models of real systems. Procedure-oriented View Real World View with Collaboration and delegation Object-oriented View Interacting objects Service Request Service Response Objects communicate with requests. A request is a Message/Stimulus specifying that an indicated operation be carried out using one or more objects and, optionally, returning a result. 8

9 View on an Anthropomorphic Object An abstraction of something (anything) in the problem domain, reflecting the capabilities of the system to keep information about it, interact with it, or both. Real or Abstract; Alive or Dead; Human-being or anything like tree, car, database, Financial Statement, Address Book, etc. Anthropomorphism ( 擬人化 ) 각각의무생물체에게이의서비스를제공하는담당관을배치함으로써 ( 서비스가있는실세계 ) 이세상모든사물또는상상의사물까지도객체지향세상에참여시킬수있고, 의인화된객체에내가해야할행위를위임 (delegation) 할수있기에나는보다더추상적이고본질적인것에집중할 (easiness) 수있으며, 의인화된객체의서비스는누구라도활용할수있기에근본적으로중복행위의배제를통해서비스의 A Cart in a real world 신뢰도 (reliability) 향상등을이룰수있는 컴포넌트기반개념의구현이용이하다. 필요한장좀봐올래? 구매목록 Public methods (APIs) additem( 상품 ) removeitem( 상품명 ) emptycart() gettotalamount() gettotalquantity() getitem( 상품명 ) listlitems() Personified shopping cart 9

10 The Perception of Object-Orient to the Real World The basic way to understand the real world. Categorization / Classification Classes (concepts, abstract) and their members - objects (real, anything that has its own identity, an instance of class) A Class Objects, the instances of a class Identified by the attributes (Unique ID) Person James, Sally, 이동국, name Student , , student ID Car Equus, Genesis, Sonata, model name Car Bus, Truck, Taxi, Private car car type Classes in MIS Java, ITSM, SAD, course no Weapon Fighter plane, Battle ship, Rifle, weapon type 10

11 Perception and Concepts A class/an object is anything to which a concept applies. Concepts shape our perception of reality. Private concepts Shared concepts People share concepts and apply them to objects. The same object can be categorized in many ways. 11

12 Object and Class in the Object-Orient An Object is an instance of a class. Is a thing, an entity, a noun, anything you can imagine that has its own identity. Is an abstraction of something in a problem domain, reflecting the capabilities of the system to keep information about it, interact with it, or both. Real-world/Software objects share two characteristics: They all have State (Attributes) : state of the object itself Behavior (Operations/Methods) : services that the object can perform A Class is the blueprint from which individual objects are created. Is a collection of objects which share common attributes and methods. Is the blueprint from which individual objects are created. Person class Name: Instance of person class 12

13 An Object in the Real-world Real-world objects share two characteristics: They all have state and behavior. Objects may be vary in complexity. some objects will also contain other objects. The real-world observations all translate into the world of object-oriented programming. For each object that you see, ask yourself two questions: "What possible states can this object be in?" and "What possible behavior can this object perform?". An Object State Behavior Dog name, color, breed, hungry barking, fetching, wagging tail Bicycle current gear, current pedal cadence, current speed changing gear, changing pedal cadence, applying brakes desktop lamp On, off turn on, turn off desktop radio Account on, off, current volume, current station accountno, customername, PIN, accountbalance turn on, turn off, increase volume, decrease volume, seek, scan, and tune Deposit, withdrawal, transfermoney 13

14 Software objects Software objects are conceptually similar to real-world objects: they too consist of state and related behavior. An object Stores its state in fields/attributes (variables in some programming languages) and exposes its behavior through methods (functions in some programming languages). Methods operate on an object's internal state and serve as the primary mechanism for object-to-object communication. Data Encapsulation Hiding internal state and requiring all interaction to be performed through an object's methods is known as data encapsulation a fundamental principle of object-oriented programming. Getter / Setter methods Blueprint / DNA of an Object, A class A bicycle modeled as a software object. 14

15 An Object in the Object-Orient An abstraction of something in a problem domain, reflecting the capabilities of the system to keep information about it, interact with it, or both. Objects are deliberately characterized as if each were a person (anthropomorphism), with a role in the system that is based on its answers to three questions. Who am I? Identity What can I do? Operations/Methods (Behavior) What do I know? Attributes (State) An instance of a Class An object is created by runtime environment at run-time. Every object has a lifecycle. 이세상모든생물체는부모에의해잉태되나, 스스로모습과성격을정하여탄생한다. Constructor Destructor 15

16 The Lifecycle of an Object Types of Events An object is created (constructor) and terminated/finalized (destructor). An object is classified, declassified, changes and as an instance of an object type. An object s attribute is changed. Some other objects initiate the lifecycle of an object. But created by itself Invoke other objects methods Create other objects if necessary Provide service when invoked by other objects Destroyed by itself 16

17 How can an Object strengthen its ability by itself? Inheritance Interface Polymorphism Dynamic behavior 17