TIM 50 - Business Information Systems

Transcription

1 TIM 50 - Business Information Systems Lecture 10 Instructor: Terry Allen UC Santa Cruz 10/28/2011

2 Outline Announcements Review Alibris Case Study Information Technology Student Presentations Client-Server Architecture The SUN N-Tier Architecture

3 Announcements Assignment 3 will be posted next week

4 Review - Alibris A start-up to sell used books on the Internet. Interloc, Alibris predecessor, functioned like a classified ads page for book dealers Alibris changing Interloc s model Actually sell the books Charge a fee per sale (instead of per listing) Intermediary strategy Buy books from dealers Ship to warehouse Re-pack, consolidate order, ship to customer

5 Architecture Copyright David G. Messerschmitt, 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.

6 What is Architecture? How do you architect a solution?

7 Architecture A system is decomposed into interacting subsystems Each subsystem may have a similar internal decomposition Slide adapted from slides for Understanding Networked Applications By David G Messerschmitt. Copyright See copyright notice

8 System Architecture System:A composition of subsystems that cooperate to accomplish some purpose Sub-system: An element within the system that performs some well-defined action on behalf of that system

9 Three properties of architecture Decomposition Organization Functionality Responsibility Interaction Cooperation Slide adapted from slides for Understanding Networked Applications By David G Messerschmitt. Copyright See copyright notice

10 Time sharing Point-to-point wire (no network) ASCII terminal (no graphics) Mainframe (database and application server)

11 Two-tier client/server Local-area network Server/ Mainframe

12 application Client Server Client client sends message to server Message is stored on POP server Later, recipient s client retrieves message from server Slide adapted from slides for Understanding Networked Applications By David G Messerschmitt. Copyright See copyright notice

13 Chat application Server Client Client Chat clients send user s typing to server Chat server aggregates typing from all users and sends to all clients Other user s clients display aggregated typing from chat server Slide adapted from slides for Understanding Networked Applications By David G Messerschmitt. Copyright See copyright notice

14 System integration Architecture -> subsystem implementation -> system integration Bring together subsystems and make them cooperate properly to achieve desired system functionality Always requires testing May require modifications to architecture and/or subsystem implementation

15 Why system decomposition in subsystems? Divide and conquer approach to reduce complexity Reuse components In accordance with industry structure Others?

16 Networked computing infrastructure Copyright David G. Messerschmitt, 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.

17 Infrastructure Layering Infrastructure decomposed into layers Each layer depends on the layer below provides services to the layer above Only interacts with layers immediately above or below E.g software is riding on top of equipment Software itself is also layered

18 Simplified infrastructure layering Application Distributed object management Network software Database management File system Middleware Operating system Network equipment Storage peripherals Equipment Communications Storage

19 Simplified infrastructure layering Application Distributed object management Network software Database management File system Middleware Operating system Network equipment Storage peripherals Equipment Communications Storage

20 Operating system functions Graphical user interface (client only) Hide details of equipment from the application Multitasking Resource management etc Processing, memory, storage, etc

21 File system (OS) Hides details of storage equipment from applications Enables services such as creating/accessing files A File is: Collection of data managed for the benefit of the application E.g. word document, excel spreadsheet Size known, but unspecified structure and interpretation Name Location in naming hierarchy

22 Network equipment Switches Hosts Backbone links Access links

23 Messages and packets Simplest network communication service is the message Smallest unit of communicated data meaningful to application Size, but unknown structure and interpretation Analogous to file in storage Internally, the network may fragment a message into packets, and reassemble those packets back into a message

24 Example Application Web server Screen Web browser HTML Operating File system File system Message Message Network Fragmentation Collection of packets Assembly Slide adapted from slides for Understanding Networked Applications By David G Messerschmitt. Copyright See copyright notice

25 Simplified infrastructure layering Application Distributed object management Network software Database management File system Middleware Operating system Network equipment Storage peripherals Equipment Communications Storage

26 Middleware Functions Capabilities that can be shared by many applications, but that is not part of OS Example: Database Management System (DBMS) Hide details of OS from application Java Virtual Machine More purposes we ll talk about later.

27 Communication middleware Location independence makes distributed application look similar to centralized Many possible other functions

28 Storage middleware Database File with specified structure Example: relational table Oriented toward business applications Database management system (DBMS) Manage multiple databases Basis of online transaction processing (OLTP)

29 A Database Year City Accommodation Tourists 2002 Oakley Bed&Breakfast Oakley Resort Oakland Bed&Breakfast Oakland Resort Berkeley Camping Berkeley Bed&Breakfast Berkeley Resort Albany Camping Albany Bed&Breakfast Oakley Bed&Breakfast Oakley Resort Oakland Bed&Breakfast Oakland Resort Berkeley Camping Berkeley Bed&Breakfast Berkeley Resort Albany Camping Albany Bed&Breakfast 6750 The DBMS enables updating and searching the database QUERIES E.g. How many B&B are there in Berkeley? E.g. What accomodation did most tourists visiting Oakley preferred?

30 Some DBMS functions Logical structure separated from physical structure Platform independence Implement standard queries Access from multiple users/applications Manage data as asset separate from applications

31 The Internet

32 Intranet Private internet intranet Often connected to Internet Global Internet Firewall creates a protected enclave Firewall

33 Extranet An Extranet is composed of Intranets connected through an unprotected domain (typically the Internet) Encryption and other security technologies used to protect proprietary information prevent imposters, vandals, etc

34 Extranet intranet Global Internet Communication between intranets encrypted. intranet

35 What is the Internet? An internet is a network of networks Interconnect standard for LAN s, MAN s, and WAN s Internet = the major global internet A private internet is called an intranet An extranet is an interconnection of intranets through the Internet

36 Intranet Extranet Firewall Global Internet Intranet

37 Extranet Internet Consumers, field workers, etc. Intranet

38 Lock icon indicates this is an extranet

39 Certificate is the server s credential

40 Questions What business purposes do nomadic workers serve? Mobile? What advantage does direct Internet access have over long distance telephony? 40

41 Ideas and examples (Chapters 4-5) by David G. Messerschmitt

42 Copyright notice Copyright David G. Messerschmitt, 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.

43 Example Application Web server Screen Web browser HTML Operating File system File system Message Message Network Fragmentation Collection of packets Assembly Slide adapted from slides for Understanding Networked Applications By David G Messerschmitt. Copyright See copyright notice

44 Peer to peer Client Server Server Client Peer Peer Slide adapted from slides for Understanding Networked Applications By David G Messerschmitt. Copyright See copyright notice

45 Three-tier client/server Local-area network Application logic Presentation Note: many clients per application server, several application servers per data server Shared data Slide adapted from slides for Understanding Networked Applications By David G Messerschmitt. Copyright See copyright notice

46 Client Host architecture Web browser HTTP Web server Application logic Common gateway interchange Databases and DBMS Application partition Slide adapted from slides for Understanding Networked Applications By David G Messerschmitt. Copyright See copyright notice

47 Departments B2B Enterprise B2C Slide adapted from slides for Understanding Networked Applications By David G Messerschmitt. Copyright See copyright notice

48 Financial institution Customers books4u.com Book distribution centers Consumer Enterprise Inter-enterprise Slide adapted from slides for Understanding Networked Applications By David G Messerschmitt. Copyright See copyright notice

49 Book merchant Web browser Consumer e-commerce Inter-enterprise e-commerce Web server Customer logic Fullfillment logic Outside links Customers Databases Merchandise Orders Acquirer bank Book distributors Slide adapted from slides for Understanding Networked Applications By David G Messerschmitt. Copyright See copyright notice

50 Clients Customer logic Acquirer bank Fullfillment logic Databases Customers Merchandise Orders Book distributors Slide adapted from slides for Understanding Networked Applications By David G Messerschmitt. Copyright See copyright notice

51 B2C Examples

52 Consumer e-commerce (B2C) What are the advantages and disadvantages compared to a retail store or direct mail catalog?

53 Some Advantages For the Consumer Check prices at many vendors with minimal effort Anonymity Mass customization Order tracking Recommendations For the Business Global reach Automate order taking (cost savings) Price Discrimination

54 Sun Case

55 Java Applets Key feature of Java Applets: chunks of Java code Initially enabled animations on web pages Later used to facilitate e-commerce applications, in cellular phones, etc. Applets are downloaded through the browser Only what and when was needed No need to keep a copy on client! Servlets: Applets that run on Webtop servers

56 Sun N-Tier

57 What would you do If you were in the executive board of Microsoft?