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A History of Java

A History of Java. SNU OOPSLA Lab. Prof Hyoung-Joo Kim. Contents. Origin of Java Why do people use Java? The Past , Present and Future of Java. Structure Overview of Java How was Java improved? The difference between Java and C++? Performance of Java Tendency on Java-related Company.

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A History of Java

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  1. A History of Java SNU OOPSLA Lab. Prof Hyoung-Joo Kim

  2. Contents • Origin of Java • Why do people use Java? • The Past , Present and Future of Java. • Structure Overview of Java • How was Java improved? • The difference between Java and C++? • Performance of Java • Tendency on Java-related Company

  3. Origin of Java(1) • Generation • James Gosling & Patrick Naughton at 1990 • Goal : to develop distributed system which is applicable to electronic products(platform independent) • *7(Star Seven) system by 1st Person Inc • named by Oak • Research Settop Box & VOD with OS(Green) • disappeared

  4. Origin of Java(2) NCSA Mosaic(1994) - first browser: Big Bang of the Web Web Browser may provide us what we want such as platform independence, security James Gosling WebRunner Browser implemented by Java Java(1995.5)

  5. Why do people use Java?(Announced by ACM, CACM) • Platform Independence • JVM과 Java API가 구현된 곳은 어디서나 수행가능 • PC서버와 NT서버가 제공하는 성능과 안정성 한계 • Productivity • Garbage Collection • C++라이브러리보다 풍부한 자바 표준 API • Reuse of Component-based code • Java Beans Component로 가능하게 됨

  6. Past, Present, Future(Addressed by the president of Java Soft) 지금까지 자바의 개발은 개발자들이 요구하는 기능 즉, API를 가능한 한 빨리 Java Platform에 수용하는 것 Past 성공적인 응용프로그램 개발을 위한 필수 기능 수용 Present Reliability, Performance and Portability의 향상 Future

  7. Java APIs Java Virtual Machine OS Platform Hardware Platform Structure Overview of Java OS application Language Primitives Auxiliary Window Tookit Servlet API JavaBeans RMI JDBC Etc. JDBC Drivers Solaris, Windows, Mac, Linux .. Web Server Sparc, Intel, Mac, HP ...

  8. How was Java improved? • JDK 1.0 • JDK 1.1 • JDK 1.2 Beta version • Java 2 Platform • J2SE-v1.3.0

  9. JDK 1.0 • Just reflect the feature of language itself andthe one of Applet • Sun didn’t pass through the alpha, beta version, and just were intended on displaying the bug-modified version • problem : huge bugs and insufficient GUI

  10. JDK 1.1 • Event model, light component framework • Additional API • JDBC, RMI, JavaBeans, 국제화.지역화지원 API • 객체 직렬화(objectserialization) • 객체에 속한 Method와 field를 알아내는 Reflection • Servlet API, Enterprise JavaBeans • 자바가 Server측에 수용되는데 밑거름이 됨

  11. JDK 1.2 beta • JDBC, RMI등의 기반 API들을 개선 • 2-Dimension Imaging과 Printing, GUI component, Security Model • CORBA의 지원(org.*) • 주로 client측의 S/W를 위한 API완성

  12. Java 2 Platform(Java 1.2의 정식버전) • API관련 • Swing(AWT의 확장), 2D API, drag&drop API, JFC • Security관련 • Policy-Based Access Control • 프로그래밍 관련 • Reflection과 Serialization에 대한 성능 개선 • HotSpot은 포함되지 않음

  13. J2SE(Java 2 platform Standard Edition - JDK1.3) • JNDI - Directory, Naming Service • RMI/IIOP - RMI와 CORBA의 연동 • Java Sound(Application에서) • Swing, AWT, Drag&Drop Enhancement • HotSpot Engine(개선된 JVM) 포함

  14. 보안 구조의 변천 JDK1.0 Security Model JDK1.2 Security Model JDK1.0 Security Model

  15. Difference between Java and C++ • Java • Single inheritance • C data type not supported • struct, union, pointer • Command line arguments • args • String • First-class object • Exception handling • Try-Catch-Finally • Garbage collection • No operator overloading • C++ • Multiple inheritance • C data type supported • Command line arguments • argc, argv • String • character array • Exception handling • Try-Catch • No garbage collection • Operator overloading

  16. Difference between Java and C++Example 1 - command line argument public class echo{ public static void main(String argv[]) { for(int i=0; i < argv.length; i++) System.out.print(argv[i] + “ ”); System.out.print(“\n”); System.exit(0); }} int main(int argc, char **argv){ for(int i = 0; i < argc; i++) printf(“%s ”, argv[i]) printf(“\n”); return 0;} $> echo arg1 arg2echo arg1 arg2$> $> java echo arg1 arg2arg1 arg2$>

  17. Difference between Java and C++Example 2 - garbage collection public void memory_function(){ Aclass cls;cls = new Aclass(…); cls.fn1(); cls.fn2(); cls.fn3(); ……….. return;} public void memory_function(){ Aclass *cls;cls = new Aclass(…); cls->fn1(); cls->fn2(); cls->fn3(); ………..delete cls; return;} 객체 생성 객체 삭제관련 코드가 없음(garbage collection)

  18. 1.0.2 1.1 1.1.6 How about performance of Java? • 성능향상을 위한 방안 • Library의 최적화 • 예: Swing Applet • Compile을 전담하는 자바 Daemon프로그램을 띄워서 Compile한다. • HotSpot Virtual Machine • Code Optimization • Thread간 동기화 속도 개선 • Memory 관리 개선 Java API중 awt가 재작성 되어서 그림과 같이 수행 속도 향상

  19. Tendency on Java-related Company • Java OS • EJB(Enterprise JavaBeans) • JINI(Embedded Solution) • Java 통합 개발환경

  20. Java OS(Standalone Environment) • Small, efficient operating environment • Executes Java application directly without requiring a host operating system • native code + java code • layered architecture

  21. 핫자바 AWT 클래스 IO.net클래스 Java Code Java OS window system Java OS Network Protocol Network file system Java OS Java OS Graphic system Java OS driver Java Virtual Machine Java OS MicroKernel Java OS Booter Java OS(Architecture) Java API C or Assembly Code H/W

  22. Java OS(Kernel) • Booting • Exceptions • Threads • Memory Management • File System • Interrupts • DMA • Debugging

  23. Java OS(Virtual Machine) • Execute the bytecodes • handle the exceptions • manages almost all of the memory(RAM) • handle the simultaneous execution of multiple threads

  24. Java OS(Device Drivers) • Written in Java • use some native codes • Memory classes • access device, memory and bus registers • Interrupt classes • managing interrupt handler

  25. Java OS(Window and Graphics) • AWT centric graphic primitives • Window system • written in java • optimized for limited memory • Graphic rendering system • mostly written in java • designed for java • support H/W graphic acceleration

  26. EJB(Enterprise JavaBeans) • 표준 분산 통합 서버측 Component 시스템 • “Write Once, Deploy anywhere!” • JPE(Java Platform for the Enterprise)의 하나 • EJB는 spec.이며 product는 아님 • Draft : Dec. 1997 • Version 1.0 : March 1998(1998 JavaOne) • Version 2.0 Q2 : 1999 • Client Java beans와는 무관

  27. EJB(Server, Container, Component) Server Container Components

  28. EJB(Session Bean) • Session Bean은 클라이언트 코드를 서버상에 확장 • 클라이언트 세션 관리. • 클라이언트 코드를 서버에 올려 Thin-Client로 만듦 • 클라이언트 Reference가 없을 때 지속적이지 못함 • Example • Banking 시스템의 입출금 행위

  29. EJB(Entity Bean) • Entity Bean은 영구적인 데이터를 표현하는 EJB • Example: EJB는 데이터베이스의 테이블의 ROW를 표현 기능 • 한 클라이언트에 종속적이지 않음(Shared Object) • 영구적인 Storage에 지속성이 있음(file, DB, etc) • Entity lifetime은 클라이언트 커넥션에 의존적임 • Entity EJB는 영구적인 Storage에 존재하는 한 존재 • Container-managed vs. Bean-managed Entity Beans

  30. EJB(Entity Bean -cont.) • Bean-managed vs. Container-managed • Bean-managed • 지속성관리를 위한 코딩을 많이 해야 함 • 지속성 관리는 배치 시 변경될 수 없음 • object/relational mapping에 대한 제어 • 만약 관계형 DBMS사용 시 SQL질의에 대한 제어 • Container-managed • 지속성관리를 위한 코딩 필요 없음 • 유연한 지속적인 스토리지 • object/relational mapping은 개발 툴 에 의해서 제안 • SQL질의에 대한 적은 제어 (generated by container) • 성능이 Bean-managed Entity Bean보다 떨어짐

  31. Environment with EJB Enterprise JavaBeans client EJB Enterprise JavaBeans EJB Enterprise JavaBeans IIOP vendor1 EJB Server EJB Server IIOP Java IDL client IIOP vendor2 vendor4 vendor5 IIOP CORBA client vendor3

  32. JINI(Introduction) • 접속과 동시에 필요한 기능을 수행하는 것을 목표로 함 (Impromptu Community) • Lookup Service에 등록된 장치들과 Service들로 구성 • 기본적으로 RMI를 통해 통신을 함 • Java의 튼튼한 보안 모델이 JINI Technology에 그대로 적용이 됨 • Packet기반 네트워크에서 객체기반의 분산 객체 컴퓨팅 환경으로 이전하는 시발점이 됨

  33. JINI(Architecture) Application Service JINI Technology(JDK, RMI, etc) Operating System(Windows, Solaris, etc) Network Transport(TCP/IP, X.25, etc) Hardware

  34. Public Network RSTN, 인터넷 Home Networking based on Jini 네트웍 카메라 전화선네트웍 전력선네트웍 홈넷허브 프린터 웹폰 홈RF IEEE 1394 엔터테이먼트 센터 컴뮤니케이션과 컨트롤 카메라 스캐너

  35. Java 통합 개발환경Borland JBulider • Borland사의 자바 개발환경 • Visual Interface사용 • JDK1.3 환경 수용 • HTML, XML, CSS viewer제공 • Survlet wizard support • Many EJB wizards • http://www.borland.com/jbuilder

  36. Java 통합 개발환경Symantec Café • Symantec의 자바 개발환경 • Visual Interface제공 • native x86 compiler제공 • Database application wizard제공 • QBE(Query by Example)포함 • 강력한 debugging tool제공 • http://www.visualcafe.com

  37. Java 통합 개발환경MS Visual J++ • Microsoft의 자바 개발환경 • Visual Interface • Microsoft의 다양한 제품들과 연동 • Java의 기본 class외에 MS에서 만든 class들을 제공(Windows Foundation Class) • http://msdn.microsoft.com/visualj

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