1. Understanding Networked Applications: A First Course Midterm one review by David G. Messerschmitt

2. Understanding Networked Applications A First Course 2 Copyright notice ©Copyright David G. Messerschmitt, 2000. This material may be used, copied, and distributed freely for educational purposes as long as this copyright notice remains attached. It cannot be used for any commercial purpose without the written permission of the author.

3. Understanding Networked Applications A First Course 3 Major topics Past and future of computing and networking –mobility, ubiquity, embedded Applications –social –information management –business –e-commerce

4. Understanding Networked Applications A First Course 4 Major topics (con’t) Information technology –information –processing, storage, communication –internet Client-server computing –two and three tier –Web

5. Understanding Networked Applications A First Course 5 Major topics (con’t) Architecture –decomposition and modularity –granularity and hierarchy –interfaces and data types Layering –network, operating system, middleware, application

6. Understanding Networked Applications A First Course 6 Major ideas Information technology –information (content) represented as data –processing –storage –communication

7. Understanding Networked Applications A First Course 7 Role of the Computer Number cruncher Information management Communication Time….

8. Understanding Networked Applications A First Course 8 Past and future Past –centralized, timeshare, decentralized, networked Future –embedded, ubiquitous, mobile

9. Understanding Networked Applications A First Course 9 Application Application = something that puts technology to use to the benefit of someone Technology = something that puts scientific principles to use

10. Understanding Networked Applications A First Course 10 Types of applications Individual = entertainment or productivity Social = groups of users Information management = access to or manipulation of information Educational = contribute to learning or training Organizational = aid mission or operations

11. Understanding Networked Applications A First Course 11 Task group Categories of user groups Individual Work group Interest group Citizenry

12. Understanding Networked Applications A First Course 12 Styles of social applications Direct Publication ImmediateDeferred

13. Understanding Networked Applications A First Course 13 A hierarchy Data Information Knowledge Wisdom

14. Understanding Networked Applications A First Course 14 Participants User Author or publisher Indexer or organizer Recommender Librarian or teacher or interpreter

15. Understanding Networked Applications A First Course 15 Push vs. pull User Publisher Pull Control over what is provided Time when it is provided Push Intermediate cases: Notification Subscription

16. Understanding Networked Applications A First Course 16 Some modalities of information access Pull Push Agent Intermediary Aggregate, filter, consolidate Delegate Search, navigate, browse Subscribe

17. Understanding Networked Applications A First Course 17 Taxonomy of organizational applications Department Enterprise Economy E-commerce: Inter-enterprise Consumer Inter-consumer

18. Understanding Networked Applications A First Course 18 Hierarchical, functional organization Suppliers Customer Activity Flow of material, goods, and information

19. Understanding Networked Applications A First Course 19 Book distribution centers books4u.com Customers Financial institution Consumer EnterpriseInter-enterprise

20. Understanding Networked Applications A First Course 20 Two flavors Supply chain management: extension of ongoing business processes to suppliers and customers –primarily business to business Marketplace: dynamic, opportunistic transactions conducted over the network –primarily business to consumer

21. Understanding Networked Applications A First Course 21 Steps in an e-commerce sale Matching buyers and sellers Negotiating terms and conditions –price, delivery, warrantee, etc. Consummation –order, fulfillment, payment Post-sale customer service

22. Understanding Networked Applications A First Course 22 Key concept The key commodity manipulated by information technology is information To be manipulated in a computing/networking environment, information must be represented by data

23. Understanding Networked Applications A First Course 23 Representation needs to be standardized Information Data Information Data Communicate data to another user or organization If the representation is not standardized, the information is garbled!

24. Understanding Networked Applications A First Course 24 Decomposition Functionality Interaction

25. Understanding Networked Applications A First Course 25 A system is decomposed into interacting subsystems Each subsystem may have a similar internal decomposition Architecture

26. Understanding Networked Applications A First Course 26 Layering Existing layers Elaboration or specialization   Layering builds capability incrementally by adding to what exists

27. Understanding Networked Applications A First Course 27 CommunicationsStorage Network equipmentStorage peripherals Network softwareFile system Distributed object management Database management Application Middleware Operating system Equipment Simplified infrastructure layering

28. Understanding Networked Applications A First Course 28 Applications Integrative services Generic services Common representations ProcessingStorageConnectivity Application components

29. Understanding Networked Applications A First Course 29 The basic idea Diversity of applications Diversity of processing, storage, and connectivity technologies Common services and representations and structures for information

30. Understanding Networked Applications A First Course 30 Hosts Switches Backbone links Access links Network architecture

31. Understanding Networked Applications A First Course 31 Presentation Application logic Shared data Local-area network Note: many clients per application server, several application servers per data server Three-tier client/server

32. Understanding Networked Applications A First Course 32 Modularity A system is modular when it is divided into subsystems (called modules) with “good” properties –Modules embody distinct functional groupings –Hierarchy supports views at different granularity and scale –Separation of concerns among modules –Reusability

33. Understanding Networked Applications A First Course 33 Software: Allows a system to be understood at different granularity Hierarchy Organization: Allows a manager to focus on high-level objectives, delegating low-level detail

34. Understanding Networked Applications A First Course 34 Interfaces Focus of module interaction and interoperability Two purposes: –informs other modules how to interact –informs implementer as to what has been promised to other modules

35. Understanding Networked Applications A First Course 35 Module interaction through interfaces Client Server action, parameters returns Both subsystems are affected by the interaction Data customizing an action and disclosing its results

36. Understanding Networked Applications A First Course 36 Layer above is a client of the layer below Layer below as as a server to the layer above ….by utilizing the services of the layer below and adding capability Each layer provides services to the layer above…. Interaction of layers

37. Understanding Networked Applications A First Course 37 Web browser File system Operating system File Network Message Collection of packets FragmentationAssembly Message HTML Screen Application Web server Example