Web Architectures Designing for the Web

multi-multi-multi-multi-multi Multi-client – PC, Mac, Unix, wireless, … Multi-server-platform – PC, Mac, Unix, watch,… Multi-tier – layers of software components Multi-threaded – concurrent processing Multi-component – CORBA, COM, javabeans,… Multi-database – Oracle, Ingres, Access, … Multi-cultural – North American, European, African, ….

Objectives  Examine current web 3-tier client/server architectures  Look at some basic E-commerce architectures

Client-Server model and Tiered Architectures  Late 1980’s  Replace centralized mainframe architectures

1-Tier Architecture Processing(a) MainMainFrame

File Server Configuration(1-Tier (b)) File Server Files 1.Ask for file 2.File 3.Process 4. Return File

Client-Server Architectures  Provide responses rather than file downloads for local processing  Message based  Serves many more users simultaneously  Tiers  2-tier  3-tier  N-tier or multi-tier

Client/Server Processing Client Server Data 1.request 2.Process request 3.response

2-Tiers

Middle Tier  Implementation Strategies  TP monitors (transaction processing monitors)  Message servers  Application servers  ORB (CORBA) Object Request Broker  Functions  Queuing  Application execution  caching

Why bother?  Scalable  Number of users  Number of transactions  Flexible  Drop applications onto different servers  Keep sophisticated applications independent of server

Fatness in Clients  Where do you want the processing ??  Fat client  Application and processing on client  Download application and every update  Thin client  Application and processing on server  More traffic

Some Design Examples  Shopping cart  B2C  B2B

Shopping Cart (B2C) Client Tier (applet/javascript) Validate format of credit card number Do “what-if” calculations Middle Tier/ Middleware (java/perl) Create catalog for display Make purchase Data Tier (Oracle, Ingres, Access, etc) Query inventory for selection of items Update inventory after sale

B2B Architecture B2C E-commerce Consumers B2B E-Commerce Business Customers Supplier’s Products Catalog Customer’s Order Information Supplier’s Electronic Mall

As a 3-Tier Architecture Supplier GUI Customer GUI Make quote Order Create Catalog Take Order Oracle UI Tier App Tier Data Tier

Internet based EDI Internet Web server EDI server database EDI legacy applications Browser

Feb 2001C.Watters19 Peer-to-peer Each party has the same capabilities Typically each party is a client-server Examples Napster – MP3 file sharing Gnutella – file sharing IBM APPN

Feb 2001C.Watters20 Peer-to-peer on the Internet Transient internet network in which users use the same application to communicate and share access to their hard drives Advantages Don’t have to move files to central server

Feb 2001C.Watters21 How to make this work on the Internet Create an application Everybody downloads the application Execute applications Connections Gnutella model – enter known IP address Napster model – enter Napster IP address

Feb 2001C.Watters22 Napster and Gnutella MP3 Central server Server collects data Server as switch for downloads Other files No central server Direct IP connections Horizon of 1000

Feb 2001C.Watters23 GarageSale Samples Client 1.1

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RECAP  Internet activity is client/server based  MultiTier architectures provide flexibility  Peer-to-peer is here!