Jim Janson

Agenda Evolution of software architectures 3-tier User interfaces Application servers Databases

In the beginning, there were mainframes…

Mainframe Architecture Advantages Simple deployment Secure Disadvantages Dumb terminals limited user interface All work performed on server

Client-Server Architecture

Client-server Architecture Advantages Richer user interfaces Processing off loaded to PCs Disadvantages Multiple copies of software; updates a problem Only so much horse power on a PC

3-Tier Architecture

Tier 1: the client contains the presentation logic “thin client” Tier 2: application server provides the business processes logic and the data access. Tier 3: the data server provides the business data.

3-Tier Architecture Easier to modify or replace any tier without affecting the other tiers. Separating the application and database functionality means better load balancing. Adequate security policies can be enforced within the server tiers without hindering the clients.

Thin Client = Web Browser User interface displayed in a web browser Top web browsers: Internet Explorer Firefox Safari Opera

Web Browsers All browsers interpret HTML and Javascript

Tools for Building Web Pages Dreamweaver Microsoft Expression Web Plus many free sites and tools

Extending the browser Active X Controls/Plug-ins Ability to support more than just HTML/Javascript Popular extensions: Flash Java Silverlight Some sites to look at:

Middle tier Ties client to data Web server Serves web pages to browser Business logic Database access

Database Server Separate computer running database software Popular databases Oracle SQL Server MySQL PostgresSQL What’s SQL?

Databases Consist of tables Each table has columns and rows (records) Each column has different attributes UserIdFirstNameLastNameStreetCity 1AbbyWentworth3 Park PlaceBoston, MA 2PetePierce34 Glass AveBerlin, NH 3SamAdams17 First StFargo, ND

SQL create table USERS ( userid number(19,0) not null, firstname varchar(30), lastname varchar(30), street varchar(100), city varchar(40) );

Storing Information A table can store millions of records Don’t want to duplicate information Use multiple tables Common information in a table

Scenario Track purchases at a web site User must create an account User logs in with account to purchase

Users Table Purchases UserIdFirstNameLastNameStreetCity 1AbbyWentworth3 Park PlaceBoston, MA 2PetePierce34 Glass AveBerlin, NH 3SamAdams17 First StFargo, ND PurchaseIdDateItemPriceUserId /11/2009Book /04/2009Wii /21/2009Rock Band49.953

Data mining Data mining is the process of extracting patterns from data. Predict trends and behaviors Discover unknown patterns Use in sales Google flu trends