1. The Evolution of Computing John R. Durrett ISQS 6343

2. Mainframe Era Mainframes –Dumb terminals –All processing on mainframe –Time Sharing –One vendor sold everything Mini-computer –Smaller mainframe –Local area network –Still centralized processing –Still host centric computing

3. Vocabulary of OOP Class - “Cookie cutter” Object - “Cookie” 3 Pillars of OO Wisdom #1 Encapsulation

4. # 2 Polymorphism # 3 Inheritance

5. Client / Server Open system Clients on PCs Server as a “specialist” –File, Database, Transaction, Groupware (fat client / thin servers) –Web Servers (thin client / fat server) Not host centric –Processes run on separate machines –Shared Resources –Transparency of location

6. C/S Limitations Remote Procedure Call driven Based on simple Transactions –Single repeated requests –Small amount of data transferred –Short lived –Static locations Limited standards Performance –Network traffic –Process management Hard to change or reconfigure

7. Distributed Objects Process based “Live anywhere on network” Well standardized –CORBA –COM “ Component ware” –History of software –OLE + Individual objects can be modified without affecting others parts of the system Agent model of computing

8. Agent Based Computing RP based higher level of abstraction applets, distributed functions virtual terminal much more flexible - less hardware/OS dependent, easier to change code

9. Software Agent “A Software program that can roam a network, interact with other agents, gather information and return home.” AI Community of the 1950’s –John McCarthy’s “software robots” –Oliver Selfridge “intelligent agent” Eliza - Weizenbaum (MIT) MUDs - Carnegie Mellon’s TinyMUD Usenet - spam, spamdectors, cancelbots IRC - chatterbots, warbots, guardbots WWW - Spiders, Wanders IBM Charlie / Microsoft Bob

10. Agent Dimensions Mobility –Office Bound (static agents) active env. monitoring –Field Workers (mobile agents) Knowledge workers “live” on remote servers Communications abilities –continuum coordination between agents –distributed artificial intelligence –Authority structure Learning

11. General Magic Agent Place Telescript Engine Transactions Mobility Communication Agent Control & Coordination Travel Agency

12. Driving forces Explosive growth in EC Competitive environment Growing complexity Information overload Decision Support/Expert System Search & Retrieval Mundane Time consuming chores Java as an Agent Platform?

13. The History of Java Oak –Green Project –small appliance user interface To Java in early 1995 Distributed programming Well accepted by developers Acceptance by users is unclear

14. Strengths Architecturally neutral –“comterpreted” –standardized APIs Multiple execution paths Managed memory system Easy –single inheritance –memory management –dynamic linking –no pointers

15. Security Program (bytecode) verification No Overflows Variables by name not memory Applets –no file i/o –limited network connectivity –no external application calls Applications

16. Java vs. C++ No structs or enums Easy to use exceptions No functions, all object oriented No multiple inheritance No operator overloading No direct memory pointers No automatic type conversions No preprocessor Dynamic linking

17. Weaknesses Java is slow –cost of interpreted language –cost of multi-threading –JIT compilers, Java chip Lack of dynamic mobility –Mobility continuum –Object state –Tcl, Telescript No uniform comm. model lack of standardized JVM

18. Tools and APIs First generation tools –JDK, Symantec Café Second generation –J++, Visual J++ –Visual Café Visual tools –Visual Age, vCafe 2.0 APIs –RogueWave –SunSoft

19. Fact Now William Blundon –“The Truth about Java,” Internet World, V7N12, Dec 1996 –Director OMG Good platform for building Client Software Easy to use and learn High Quality code database access Java Beans

20. Promises for the future? Good for Server Applications –I/O –execution speed Secure Write once & port anywhere Is it safe to bet on Java?