Date post: | 20-Dec-2015 |
Category: |
Documents |
View: | 219 times |
Download: | 5 times |
Understanding Networked Applications A First Course2
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.
Understanding Networked Applications A First Course3
Major topics
• Past and future of computing and networking– mobility, ubiquity, embedded
• Applications– social– information management– business– e-commerce
Understanding Networked Applications A First Course4
Major topics (con’t)
• Information technology– information– processing, storage, communication– internet
• Client-server computing– two and three tier– Web
Understanding Networked Applications A First Course5
Major topics (con’t)
• Architecture– decomposition and modularity– granularity and hierarchy– interfaces and data types
• Layering– network, operating system, middleware,
application
Understanding Networked Applications A First Course6
Major ideas
• Information technology– information (content) represented as data– processing– storage– communication
Understanding Networked Applications A First Course7
Role of the Computer
Number cruncher
Informationmanagement
Communication
Time….
Understanding Networked Applications A First Course8
Past and future
• Past– centralized, timeshare, decentralized,
networked
• Future– embedded, ubiquitous, mobile
Understanding Networked Applications A First Course9
Application
• Application = something that puts technology to use to the benefit of someone
• Technology = something that puts scientific principles to use
Understanding Networked Applications A First Course10
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
Understanding Networked Applications A First Course11
Task group
Categories of user groups
Individual
Work group
Interest group
Citizenry
Understanding Networked Applications A First Course12
Styles of social applications
Direct
Publication
Immediate Deferred
Understanding Networked Applications A First Course13
A hierarchy
• Data
• Information
• Knowledge
• Wisdom
Understanding Networked Applications A First Course14
Participants
User
Author or publisher
Indexer or organizer
Recommender
Librarian or teacher or interpreter
Understanding Networked Applications A First Course15
Push vs. pull
User
Publisher
Pull
Control over what is providedTime when it is provided
PushIntermediate cases:
NotificationSubscription
Understanding Networked Applications A First Course16
Some modalities of information accessPull
Push
Agent
Intermediary
Aggregate,filter,consolidate
Delegate
Search,navigate,browse
Subscribe
Understanding Networked Applications A First Course17
Taxonomy of organizational applications
Department
Enterprise
Economy
E-commerce:Inter-enterpriseConsumerInter-consumer
Understanding Networked Applications A First Course18
Hierarchical,functional organization
Suppliers
Customer
ActivityFlow of material,goods, and information
Understanding Networked Applications A First Course19
Book distributioncenters
books4u.comCustomers
Financial institution
Consumer Enterprise Inter-enterprise
Understanding Networked Applications A First Course20
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
Understanding Networked Applications A First Course21
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
Understanding Networked Applications A First Course22
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
Understanding Networked Applications A First Course23
Representation needs to be standardized
Information
Data
Information
Data
Communicate data toanother user or organization
If the representationis not standardized, theinformation is garbled!
Understanding Networked Applications A First Course24
Decomposition
Decomposition
Functionality
Interaction
Understanding Networked Applications A First Course25
A system is decomposed into interacting subsystems
Each subsystem may have a similar internal decomposition
Architecture
Understanding Networked Applications A First Course26
Layering
Existing layers
Elaboration or specialization
Layering builds capability incrementally by adding to what exists
Understanding Networked Applications A First Course27
Communications Storage
Network equipment Storage peripherals
Network software File system
Distributed objectmanagement
Databasemanagement
Application
Middleware
Operatingsystem
Equipment
Simplified infrastructure layering
Understanding Networked Applications A First Course28
Applications
Integrative services
Generic services
Common representations
Processing Storage Connectivity
Application components
Understanding Networked Applications A First Course29
The basic idea
Diversity of applications
Diversity of processing, storage, andconnectivity technologies
Common services andrepresentationsand structures forinformation
Understanding Networked Applications A First Course30
Hosts
Switches
Backbonelinks
Access links
Network architecture
Understanding Networked Applications A First Course31
Presentation
Applicationlogic
Shareddata
Local-area network
Note: many clients perapplication server, severalapplication servers per data server
Three-tier client/server
Understanding Networked Applications A First Course32
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
Understanding Networked Applications A First Course33
Software:
Allows a system to be understood at different granularity
Hierarchy
Organization:Allows a managerto focus on high-levelobjectives, delegatinglow-level detail
Understanding Networked Applications A First Course34
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
Understanding Networked Applications A First Course35
Module interaction through interfaces
Client Server
action, parameters
returns
Both subsystems areaffected by the interaction
Data customizing an actionand disclosing its results
Understanding Networked Applications A First Course36
Layer above is a client of thelayer below
Layer below as as a serverto 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